Written statement of Antigua and Barbuda

INTERNATIONAL COURT OF JUSTICE
OBLIGATIONS OF STATES IN RESPECT OF
CLIMATE CHANGE
WRITTEN STATEMENT OF
ANTIGUA AND BARBUDA
22 March 2024

i
TABLE OF CONTENTS
Page
I. Introduction to the Written Statement ...................................................................... 1
A. Introduction and importance of the request ................................................. 1
B. The process leading to the request for an advisory opinion......................... 2
C. Overview and executive summary of this Written Statement ..................... 4
II. Factual and Scientific Background ............................................................................ 6
A. Introduction and roadmap .............................................................................. 6
B. How anthropogenic GHG emissions cause climate change.......................... 9
1. How human activity leads to GHG emissions and how these
emissions impact the climate system .................................................. 9
2. The present and expected impact of human activity on climate
change.................................................................................................. 11
3. The historical carbon budget: How much States have already
contributed to climate change ........................................................... 13
4. The remaining carbon budget: How much States can still emit to
limit climate change ........................................................................... 15
C. The impact of anthropogenic GHG emissions on the environment and
human populations......................................................................................... 18
1. The key drivers of harm: temperature increase, sea level rise and
ocean acidification .............................................................................. 20
2. How anthropogenic GHG emissions harm the environment ......... 28
3. How anthropogenic GHG emissions harm human populations .... 34
D. Efforts to address climate change ................................................................. 40
1. States are failing to effectively address climate change .................. 40
2. Concrete policy options are available for States to effectively
address climate change ...................................................................... 43
III. Question (A): Relevant Obligations and Their Content ......................................... 47
ii
A. Key international rules and principles ......................................................... 48
1. The obligation of prevention ............................................................. 48
2. The principle of common but differentiated responsibilities and
respective capabilities in light of different national circumstances
.............................................................................................................. 53
3. Climate change regime ...................................................................... 55
4. International human rights law ........................................................ 60
5. United Nations Convention on the Law of the Sea ......................... 69
6. Convention on Biological Diversity .................................................. 72
7. International trade law ...................................................................... 73
B. What are the obligations of States under international law to ensure the
protection of the climate system and other parts of the environment from
anthropogenic GHG emissions? ................................................................... 77
1. Obligations related to mitigation ...................................................... 77
2. Obligations related to adaptation ................................................... 127
3. Obligations related to the provision of support ............................ 135
IV. Question (B): Legal Consequences ......................................................................... 154
A. Introduction .................................................................................................. 154
B. The law governing legal consequences ....................................................... 155
C. The legal consequences for responsible States .......................................... 156
1. The establishment of State responsibility ...................................... 156
2. The content of State responsibility ................................................. 157
3. The invocation of State responsibility ............................................ 167
D. Application of the rules of State responsibility in the context of climate
change............................................................................................................ 174
1. Legal consequences of violation of mitigation obligations ........... 176
2. Legal consequences of violation of adaptation obligations .......... 182
3. Legal consequences of violation of support obligations................ 183
iii
E. Conclusion .................................................................................................... 185
Certification .......................................................................................................................... 187
List of Annexes to the Written Statement.......................................................................... 188
iv
LIST OF FIGURES
Figure 1: Summary of causal pathways from anthropogenic GHG emission to environmental
and human harm (Source: IPCC) ............................................................................................... 8
Figure 2: Annual CO2 emissions over time (Source: Our World in Data) .............................. 12
Figure 3: Historical cumulative fossil CO2 emissions since 1850 (Source: Global Carbon
Project) ..................................................................................................................................... 15
Figure 4: The total carbon budget to limit global warming to 1.5°C (Sources: IPCC & Global
Carbon Budget) ....................................................................................................................... 18
Figure 5: Global surface air temperature (Source: Copernicus Global Climate Highlights 2023)
.................................................................................................................................................. 21
Figure 6: Daily global temperature increase above pre-industrial level (1850-1900) in 2023
(Source: Copernicus Global Climate Highlights 2023) ........................................................... 22
Figure 7: Loss of territory for Barbuda resulting from sea level rise (Source: Climate Central
Mapping) .................................................................................................................................. 26
Figure 8: Populations living in small islands that may be exposed to coastal inundation by 2100
under RCP 4.5 (Source: IPCC) ................................................................................................ 36
Figure 9: “Many options available now in all sectors are estimated to offer substantial potential
to reduce net emissions by 2030” (Source: IPCC)................................................................... 46
Figure 10: The total carbon budget to limit global warming to 1.5°C (Sources: IPCC & Global
Carbon Budget) ........................................................................................................................ 89
v
LIST OF ABBREVIATIONS
Abbreviation Description
ACHPR African Commission on Human and Peoples’ Rights
ACHR American Convention on Human Rights
AFOLU Agriculture, Forestry and Other Land Uses
CBD Convention on Biological Diversity
CBDR-RC Common but Differentiated Responsibility and Respective
Capabilities
CEDAW Convention on the Elimination of All Forms of Discrimination
against Women
CESCR United Nations Committee on Economic, Social and Cultural
Rights
CO2 Carbon Dioxide
COP Conference of the Parties
COSIS Commission of Small Island States on Climate Change and
International Law
CRC Convention on the Rights of the Child
CRPD Convention on the Rights of Persons with Disabilities
DSU Understanding on Rules and Procedures Governing the Settlement
of Disputes
ECHR European Convention for the Protection of Human Rights and
Fundamental Freedoms
EIA Environmental Impact Assessment
GATT 1994 General Agreement on Tariffs and Trade 1994
GDP Gross Domestic Product
GHG Greenhouse Gases
GNI Gross National Income
GtCO2 Giga Tonne of CO2 (1 billion tonnes)
IACHR Inter-American Court of Human Rights
vi
Abbreviation Description
ICCPR International Covenant on Civil and Political Rights
ICERD International Convention on the Elimination of All Forms of Racial
Discrimination
ICESCR International Covenant on Economic Social and Cultural Rights
ICJ International Court of Justice
ICRMW International Convention on the Protection of the Rights of All
Migrant Workers
ILC International Law Commission
IMF International Monetary Fund
IPBES Intergovernmental Science-Policy Platform on Biodiversity and
Ecosystem Services
IPCC Intergovernmental Panel on Climate Change
ITLOS International Tribunal for the Law of the Sea
IUCN International Union for Conservation of Nature
LDC Least Developed Country
MVI Multidimensional Vulnerability Index
NCQG New Collective Quantified Goal
NDC Nationally Determined Contribution
OAS Organization of American States
OHCHR The United Nations Office of the High Commissioner for Human
Rights
RCB Remaining Carbon Budget
SIDS Small Island Developing States
TESS Forum on Trade, Environment, and the Sustainable Development
Goals
TRIPS Agreement on Trade-Related Intellectual Property Rights
UDHR Universal Declaration of Human Rights
vii
Abbreviation Description
UN United Nations
UNCLOS The United Nations Convention on the Law of the Sea
UNDP United Nations Development Programme
UNEP United Nations Environment Programme
UNFCCC United Nations Framework Convention on Climate Change
UNGA United Nations General Assembly
USD United States Dollars
VCLT Vienna Convention on the Law of Treaties
WMO World Meteorological Organization
WTO World Trade Organization
1
I. INTRODUCTION TO THE WRITTEN STATEMENT
A. Introduction and importance of the request
1. Climate change is, unequivocally, the greatest challenge of our time. The severity of
the harms that climate change has caused, and will continue to cause, to the world’s
ecosystems, biodiversity, and human populations, cannot be overstated. These harms
will “escalate with every increment of global warming”.1 For small island developing
States (“SIDS”) – like Antigua and Barbuda – the threat is, literally, existential.
Although SIDS have made a negligible contribution to the causes of climate change,
they are already suffering loss and damage, and will continue to suffer the greatest
consequences. The international community is now facing a “rapidly closing window
of opportunity to secure a liveable and sustainable future for all”.2
2. Given the severity of the existential threat posed by climate change, Antigua and
Barbuda underscores the significance of these advisory proceedings, and of similar
initiatives championed by SIDS in an attempt to address this common concern of
humankind. Antigua and Barbuda commends the international community in agreeing
unanimously to submit this request for an advisory opinion.3 The request is, in Antigua
and Barbuda’s view, well-formulated to allow the Court to address these issues of
unprecedented importance.
3. Antigua and Barbuda commends United Nations (“UN”) General Assembly Resolution
77/276 as a call to secure clarity on the obligations of States in relation to climate
change, and the legal consequences of the breach of those obligations. Such clarity has
very important real-world significance. Quite literally, without greater clarity on the
issues addressed in these advisory proceedings, Antigua and Barbuda’s very existence
would be at risk.
4. Similar initiatives have been championed in other international fora, specifically,
through requests for Advisory Opinions from the Inter-American Court of Human
1 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.2.
2 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. C.1.
3 UN General Assembly, Resolution 77/276: Request for an advisory opinion of the International Court of
Justice on the obligations of States in respect of climate change, UN Doc. A/RES/77/276, 29 March 2023.
2
Rights (“IACHR”) and the International Tribunal for the Law of the Sea (“ITLOS”).
Antigua and Barbuda is a founding Member of the Commission of Small Island States
on Climate Change and International Law (“COSIS”). The mandate of COSIS is to
“promote and contribute to the definition, implementation, and progressive
development of rules and principles of international law concerning climate change”,
including the “responsibility [of States] for injuries arising from internationally
wrongful acts in respect of the breach of such obligations”.4 COSIS has championed
the request for an Advisory Opinion from ITLOS. The present advisory proceedings
supplement other initiatives championed by the SIDS at other fora.
5. Given the Court’s role as the principal judicial organ of the UN and the breadth of areas
of international law encompassed by the advisory opinion request, the present
proceedings are a unique opportunity to ensure coherence and clarity in international
law as it applies to climate change. It is in view of the unique importance of the present
proceedings, and in solidarity with the SIDS and the international community, that
Antigua and Barbuda submits this Written Statement.
6. This Section proceeds as follows. Sub-section I.B provides an overview of the process
leading to the request for an advisory opinion from the International Court of Justice
(“ICJ” or the “Court”); and sub-section I.C provides an overview of this Written
Statement.
B. The process leading to the request for an advisory opinion
7. On 29 March 2023, the UN General Assembly adopted Resolution 77/276 entitled
“Request for an advisory opinion of the International Court of Justice on the obligations
of States in respect of climate change”.5 In that resolution, the General Assembly
decided, pursuant to Article 96 of the Charter of the UN, to request the ICJ to render an
advisory opinion on the following questions:
Having particular regard to the Charter of the United Nations,
the International Covenant on Civil and Political Rights, the
International Covenant on Economic, Social and Cultural
Rights, the United Nations Framework Convention on Climate
4 Agreement for the establishment of the Commission of Small Island States on Climate Change and
International Law, 31 October 2021, 3447 U.N.T.S. 1, Article 1(3).
5 UN General Assembly, Resolution 77/276: Request for an advisory opinion of the International Court of
Justice on the obligations of States in respect of climate change, UN Doc. A/RES/77/276, 29 March 2023.
3
Change, the Paris Agreement, the United Nations Convention on
the Law of the Sea, the duty of due diligence, the rights
recognized in the Universal Declaration of Human Rights, the
principle of prevention of significant harm to the environment
and the duty to protect and preserve the marine environment,
(a) What are the obligations of States under international
law to ensure the protection of the climate system and
other parts of the environment from anthropogenic
emissions of greenhouse gases for States and for present
and future generations;
(b) What are the legal consequences under these
obligations for States where they, by their acts and
omissions, have caused significant harm to the climate
system and other parts of the environment, with respect
to:
(i) States, including, in particular, small island
developing States, which due to their
geographical circumstances and level of
development, are injured or specially affected by
or are particularly vulnerable to the adverse
effects of climate change?
(ii) Peoples and individuals of present and future
generations affected by the adverse effects of
climate change?
8. On 12 April 2023, the UN Secretary-General transmitted the Request to the Court.6 On
20 April 2023, the Court fixed time-limits within which written statements on the
questions may be submitted to the Court.7 On 21 April 2023, in accordance with
Article 66(2) of the Statute of the Court, the Registrar of the Court informed Antigua
and Barbuda that it may submit a written statement in the proceedings.8 On 4 August
2023 and 15 December 2023, the Court extended the time-limits for the filing of written
statements.9 Antigua and Barbuda submits this Written Statement pursuant to the
Court’s invitation and within the time-limit set by the Court.
6 Letter from the UN Secretary-General to the President of the International Court of Justice, 12 April 2023.
7 Obligations of States in Respect of Climate Change (Request for an Advisory Opinion), I.C.J. General List
No. 187, Order of the Court, 20 April 2023.
8 Letter from the Registrar of the Court to the Permanent Representative of Antigua and Barbuda to the UN,
Permanent Mission of Antigua and Barbuda, 21 April 2023.
9 Obligations of States in Respect of Climate Change (Request for an Advisory Opinion), I.C.J. General List
No. 187, Order of the Court, 4 August 2023 and Order of 15 December 2023.
4
C. Overview and executive summary of this Written Statement
9. This Written Statement proceeds in three further Sections.
10. Section 0 sets out the factual and scientific background to the climate crisis, drawing
predominantly on the extensive work of the Intergovernmental Panel on Climate
Change (“IPCC”). This Section establishes the unequivocal link between human
activity – specifically, anthropogenic Greenhouse Gas (“GHG”) emissions – and
climate change, including the historical contributions made to the crisis, as well as the
myriad resulting harms to the environment and human populations.
11. Section III of the Written Statement addresses the first question posed to the Court,
Question (A), proceeding in two sub-sections. Sub-section III.A identifies and
describes the key international rules and principles relevant to climate change, focusing
in particular on: (1) the customary obligation of prevention; (2) the principle of common
but differentiated responsibilities and respective capabilities, in light of different
national circumstances (“CBDR-RC”); (3) the international climate change regime,
including the United Nations Framework Convention on Climate Change
(“UNFCCC”) and the Paris Agreement; (4) international human rights law; (5) the
United Nations Convention on the Law of the Sea (“UNCLOS”); (6) the Convention
on Biological Diversity (“CBD”); and (7) international trade law.
12. Sub-section III.B synthesises these various rules and principles to identify what States
are obliged to do under international law to ensure the protection of the climate system
and other parts of the environment from anthropogenic GHG emissions. Subsection
III.B proceeds in three further sub-sections.
(a) Sub-section III.B.1 addresses obligations related to mitigation, identifying
that States are under an obligation to do their utmost, using all the means at their
disposal, to achieve rapid, deep and sustained emissions reductions sufficient to
prevent significant environmental harm, in a manner consistent with fairness,
equity, and the principle of CBDR-RC. This obligation arises independently
under several sources of law, in particular under the international climate
change regime; the customary obligation of prevention; human rights law; and
UNCLOS. In each instance, the obligations arising under one source of law
support those arising under the other sources. Further, where States unilaterally
5
adopt trade-related climate measures (e.g., border charges and restrictions),
international trade law requires them to first engage in good-faith cooperative
efforts with affected countries, and to respect the principle of fairness, equity
and CBDR-RC in the design of those measures.
(b) Sub-section III.B.2 addresses obligations related to adaptation, identifying
that States are under an obligation to engage in adaptation planning processes
and to implement adaptation actions; however, this obligation is qualified by
what is “appropriate” for the State in question, including (for developing
countries) the adequacy of adaptation support.
(c) Sub-section III.B.3 addresses obligations related to support, identifying an
obligation on developed States to provide both financial support and technology
support for developing States’ mitigation and adaptation efforts. On the former,
the level of financial support must be at a level adequate to meet this purpose,
with SIDS and other uniquely vulnerable countries enjoying priority in the
allocation of these resources.
13. Section 0 of the Written Statement addresses the second question posed to the Court,
Question (B). The second question asks the Court to identify “the legal consequences”
for States where they have breached the obligations that are the subject of the first
question, proceeding in two sub-sections. Sub-section IV.A explains how customary
international law on State responsibility applies in the context of climate change. Subsection
IV.B then applies these rules to identify the legal consequences that flow from
the violation of the primary obligations identified in response to the first question.
These rules are of particular significance for those States – such as Antigua and Barbuda
– that have made a negligible contribution to the climate crisis, but have suffered, and
will continue to suffer, disproportionate loss and damage as a result thereof.
6
II. FACTUAL AND SCIENTIFIC BACKGROUND
A. Introduction and roadmap
14. In this Section, Antigua and Barbuda sets out the factual and scientific background
relevant to the questions before the Court.
15. This Written Statement draws on the work of recognised international scientific bodies,
in particular that of the IPCC and the Intergovernmental Science-Policy Platform on
Biodiversity and Ecosystem Services (“IPBES”).10 Both are independent,
intergovernmental bodies established by States to strengthen the science-policy
interface on, among others, climate and biodiversity issues.
16. Sub-section B sets out how anthropogenic GHG emissions cause climate change. It
explains the scientific basis for the IPCC’s “unequivocal” conclusion that
anthropogenic GHG emissions are causing warming to the earth’s atmosphere and
oceans, leading to the climate crisis (B.1). It sets out the present and expected impact
of human activity on climate change (B.2); explains the disparities in how States’
historical activities have already contributed to climate change (B.3); and sets out the
IPCC’s findings on the Remaining Carbon Budget (“RCB”) available to States, i.e.,
how much carbon can be emitted while still limiting warming to certain temperature
levels (B.4).
17. Section C addresses how anthropogenic emissions, through their impact on the climate
system, cause harm to the environment. It identifies the key drivers of harm resulting
from anthropogenic emissions: increased temperatures (land and ocean); rising sea
levels; and ocean acidification (C.1). It next unpacks the harms that flow, as a
consequence, to the environment: extreme weather events, coastal erosion, inundation
and salination, and severe habitat and biodiversity loss (C.2). The sub-section then
10 The IPCC was established in 1988 by the World Meteorological Organization (“WMO”) and the United
Nations’ Environment Program (“UNEP”) (see, here). This Written Statement also refers to the report
“Science of Climate Change and the Caribbean: Findings from the Intergovernmental Panel on Climate
Change IPCC) Sixth Assessment Cycle (AR6)”, 5 March 2024, authored by Dr. Adelle Thomas, Professor
Michelle Mycoo, and Professor Michael Taylor (available as Annex 1 attached to this Written Statement)
(hereinafter, “Caribbean Climate Science Report, March 2024 (Annex 1)”). The Caribbean Climate
Science Report provides an overview of the scientific consensus on the causes, impacts and risks of climate
change for the Caribbean region, based on the most recent reports of the IPCC. IPBES was established in
2012 in recognition of the need for an intergovernmental science-policy platform on biodiversity and
ecosystem services (see, here).
7
describes the consequential harms to human populations: full or partial loss of territory;
harm to human physical and mental health; compromised access to food and water;
damage to cities, settlement and infrastructure; and forced migration and displacement
(C.3).
18. Section D explains that – according to the Conference of the Parties (“COP”) Global
Stocktake Decision of December 2023 – States current efforts to address climate change
are insufficient (D.1), notwithstanding the availability of concrete and cost-effective
policy options for reducing emissions (D.2).
19. The causal pathways linking anthropogenic GHG emissions to environmental and
human harms are summarised in Figure 1 below.
8
Figure 1: Summary of causal pathways from anthropogenic GHG emission to environmental and human harm (Source: IPCC)
9
B. How anthropogenic GHG emissions cause climate change
1. How human activity leads to GHG emissions and how these
emissions impact the climate system
20. Climate change is caused by the release of the following GHGs into the Earth’s
atmosphere: (1) carbon dioxide (“CO2”); (2) methane; (3) nitrous oxide; and (4) other
GHGs such as “fluorinated gases”.11 The first three are naturally occurring, but have
also been released in large volumes through a variety of human activities
(“anthropogenic” GHGs), while fluorinated gases are generated exclusively by human
activities. Once accumulated in the atmosphere, GHGs trap the sun’s radiation around
the Earth, leading to a “greenhouse” warming effect.
21. The contribution that each GHG makes to climate change is a function of several
factors: the volume of emissions over time; the effectiveness of the molecular structure
in trapping heat in the atmosphere (its “potency”); and the length of time the gas
remains in the atmosphere (its “atmospheric lifetime”). The following points should be
noted for the four categories of GHGs.
22. First, the most significant GHG is CO2, making up approximately 64 percent of annual
GHG emissions.12 In 2019, atmospheric concentrations of CO2 were higher than at any
time in the last 2 million years.13 Most CO2 is emitted through the combustion of fossil
fuels (e.g., coal, oil, gas, and peat) in energy conversion systems like boilers in electric
power plants, engines in aircraft and automobiles, and in cooking and heating.14
Deforestation and related land-use changes also result in the release of CO2 stored in
biomass (e.g., burning felled trees), and the destruction of carbon sinks which remove
CO2 from the atmosphere. CO2 can remain in the atmosphere for up to approximately
1,000 years.15 Practically, this means that much of the CO2 emitted since the pre-
11 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), p. 194.
12 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), p. 194.
13 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), para. A.2.1.
14 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), p. 194.
15 The precise atmospheric lifetime of CO2 released into the atmosphere can vary; see, IPCC, Fourth Assessment
Report, 2007, The Physical Science Basis (Working Group I), Technical Summary (available here), p. 77;
“The Atmosphere: Getting a Handle on Carbon Dioxide”, NASA News, 9 October 2019 (available here).
10
industrial period (i.e., 1850-1900) is still present in the atmosphere today; and that CO2
emitted today will remain in the atmosphere – and have a warming effect – for
potentially up to 1,000 years.
23. Second, the second biggest GHG contributor to climate change is methane. Although
methane makes up only 18 percent of annual emissions,16 its greenhouse effect is highly
potent, absorbing significantly more energy as long as it remains in the atmosphere.17
Methane is released through fossil fuel combustion, as well as large-scale agricultural
processes, and the breakdown of rubbish in landfills.18 Methane has an atmospheric
lifetime of approximately 12 years.19
24. Third, nitrous oxide, while only a small percentage of total annual emissions, is
extremely potent: 300 and 15 times more potent than CO2 and methane, respectively.20
It is released through fossil fuel combustion and certain agricultural and industrial
processes, and has an atmospheric lifetime of approximately 114 years.21
25. Fourth, and finally, other GHGs include “fluorinated gases” – artificial compounds
generated exclusively from human industrial activities (e.g., manufacture and use of
refrigerators, air-conditioners, and industrial solvents). Fluorinated gas emissions are
small in volume but extremely potent, with some having a greenhouse effect several
thousand times greater than CO2.22
16 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full
Report (available here), p. 229.
17 International Energy Agency, “The Imperative of Cutting Methane from Fossil Fuels: an assessment of the
benefits from the climate and health”, October 2023 (available here), p. 4.
18 International Energy Agency, “Global Methane Tracker 2023: Understanding methane emissions” (available
here); UNEP/Climate and Clean Air Coalition, “Global Methane Assessment: 2030 Baseline Report”
(available here), p. 9.
19 International Energy Agency, “Global Methane Tracker 2023: Understanding methane emissions” (available
here); see also, IPCC, Fourth Assessment Report, 2007, The Physical Science Basis (Working Group I), Full
Report (available here), p. 212.
20 See, IPCC, Fourth Assessment Report, 2007, The Physical Science Basis (Working Group I), Full Report
(available here), p. 212. See also, University Corporation for Atmospheric Research, “Some Greenhouse
Gases Are Stronger than Others” (available here); Inside Climate News, “What is Nitrous Oxide and Why is
it a Climate Threat?”, 11 September 2019 (available here).
21 IPCC, Fourth Assessment Report, 2007, The Physical Science Basis (Working Group I), Full Report (available
here), p. 212; see also, The World Bank, “Metadata Glossary: Nitrous oxide emissions” (available here).
22 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Full Report (available
here), p. 180. See also, IPCC, Fourth Assessment Report, 2007, The Physical Science Basis (Working Group
I), Full Report (available here), p. 212.
11
2. The present and expected impact of human activity on climate
change
26. The international scientific community has reached an “unequivocal” conclusion that
anthropogenic GHGs have caused, and are causing, drastic and accelerated changes to
the Earth’s climate system.23 In the IPCC’s words, “human influence on the climate
system is now an established fact”.24
27. Temperatures in the context of climate change are typically identified as the rise since
“pre-industrial levels”, i.e., 1850-1900, the point at which climate change due to largescale
anthropogenic emissions is understood to have begun.
28. As shown in Figure 2 below, annual global CO2 emissions were very low in the preindustrial
period, and increased thereafter. Growth in CO2 emissions was relatively low
until 1950 (at around 6 billion tonnes per year), and grew exponentially thereafter –
reaching more than 22 billion tonnes in 1990 and more than 34 billion tonnes per year
today.25 Annual global CO2 emissions continue to grow, albeit at a slower pace.
23 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), para. A1; see also, Caribbean Climate Science Report, March 2024 (Annex 1),
pp. 8 and 12.
24 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Technical Summary
(available here), p. 41.
25 See, University of Oxford and Global Change Data Lab, Our World in Data, “CO₂ and Greenhouse Gas
Emissions” (available here).
12
Figure 2: Annual CO2 emissions over time (Source: Our World in Data)
29. As a result of the cumulative global emissions, atmospheric temperatures have already
warmed by, on average, approximately 1.1°C to 1.35°C since pre-industrial levels.26
Today’s level of global warming has already caused, and continues to cause, severe,
and in some cases, irreversible, environmental and human harm. These effects are
discussed in detail below.27
30. The IPCC develops estimates for future temperature increases. That is, the IPCC
assesses the rate and degree of warming using a set of tools, including integrated
assessment models, climate models and paleoclimatic insights.28 On this basis, the IPCC
26 The precise degree of average post-industrial warming is subject to some uncertainty, depending on
methodological factors such as the reference period over which average warming is measured. The IPCC’s
Sixth Assessment Report, released in 2021, confirms that human activities are responsible for approximately
1.1°C of post-industrial warming. See, IPCC, Sixth Assessment Report, 2021, The Physical Science Basis
(Working Group I), Summary for Policymakers (available here), A.1.2.
However, factoring in more recent data from 2022/2023, newer estimates calculate still higher levels of
warming of up to, on average, 1.35°C. Further, 2023 is now the first year to have reached, on average across
the year, 1.5°C. See, Financial Times, “Climate Graphic of the Week: Critical 1.5°C threshold breached over
12-month period for first time”, 8 February 2024 (available here); see also, Copernicus, “Global Climate
Highlights 2023: 2023 is the hottest year on record with global temperatures close to the 1.5°C limit” (available
here); Berkeley Earth, “Global Temperature Report for 2023”, 12 January 2024 (available here).
27 See, Section II.C.2 and Section II.C.3, below.
28 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report (available
here), p. 63, footnote 109.
13
is able to provide an estimated range of what warming will likely occur in a given
scenario (e.g., high, medium and low mitigation efforts, plus additional variables).
31. The IPCC modelling process naturally involves uncertainty. While the fact of warming
driven by anthropogenic emissions is “unequivocal”, the ceiling and rate of future
warming is not certain. The IPCC has warned that, for each given scenario, “warming
substantially above the assessed very likely range… cannot be ruled out”.29 In other
words, future warming could be higher than the currently estimated top end of estimated
warming (approximately 4.4°C).30
32. In this modelling exercise, the IPCC calculates an estimated temperature increase for
each of a set of different scenarios that vary depending on, for instance, the depth and
speed of States’ mitigation efforts.
33. In addition, the IPCC also conducts modelling exercises which calculate the quantity
of GHG emissions that can be released for warming to stay below a certain temperature
level (for instance 1.5°C). This quantity is called the “total carbon budget”: the
maximum amount of cumulative net global anthropogenic CO2 emissions that would
result in limiting global warming to a given level (within a certain probability).
34. The total carbon budget is the sum of: (i) the historical carbon budget (that is historical
cumulative net CO2 emissions); and, (ii) the remaining carbon budget (that is the future
cumulative net CO2 emissions to keep global warming to a given level). Antigua and
Barbuda discusses these two aspects of the total carbon budget in turn.
3. The historical carbon budget: How much States have already
contributed to climate change
35. As a result of historical emissions, atmospheric temperature has increased already by
up to 1.35°C since pre-industrial levels.31
36. Historical cumulative emissions (between 1890-2023) constitute the largest share of the
total carbon budget that can be exploited while keeping the temperature increase below
29 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report (available
here), p. 77.
30 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report (available
here), p. 68.
31 See, para. 29, above.
14
1.5°C, accounting for about 90 percent of the total carbon budget.32 This means that
the remaining carbon budget – the carbon which States could still emit while staying
below 1.5°C – is only about 10 percent of the total carbon budget (see Section II.B.4,
below).
37. Historical emissions, therefore, carry a large responsibility for causing, and continuing
to cause, climate change.33 This responsibility is, however, not shared equally across
States.34
38. Figure 3 below shows the significant regional disparity in historical CO2 emissions.35
Until the mid-20th century, global emissions were dominated by Europe and the United
States; thereafter, emissions picked up in other regions, in particular in Eastern Asia.
Overall, the United States is responsible for approximately 24 percent of cumulative
CO2 emissions, the 27 EU Member States for approximately 17 percent, and China for
approximately 15 percent.36
32 Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5327.
33 Carbon Brief, “Revealed: How colonial rule radically shifts historical responsibility for climate change”,
26 November 2023 (available here).
34 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), p. 64; see also, Caribbean Climate Science Report, March 2024 (Annex 1), p. 8-9.
35 See, University of Oxford and Global Change Data Lab, Our World in Data, “Cumulative CO₂ emissions by
world region” (available here). This does not include CO2 emissions from land use change.
36 Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5319.
15
Figure 3: Historical cumulative fossil CO2 emissions since 1850 (Source: Global Carbon
Project)
39. By contrast, all SIDS together – the countries which are most vulnerable to the effects
of climate change – have contributed only 0.5 percent to the total volume of CO2
emissions.37
40. Antigua and Barbuda, for its part, has emitted a mere 0.001 percent of global CO2
emissions.38 This number is even inflated because it includes emissions from before
Antigua and Barbuda’s independence from colonial rule (in November 1981).
4. The remaining carbon budget: How much States can still emit to
limit climate change
41. Currently, as a result of historical emissions, the global atmospheric temperature has
already increased by between 1.1°C – 1.35°C on average since pre-industrial levels.
Every additional tonne of GHG emissions adds to global warming. In fact, there is a
near-linear relationship between anthropogenic CO2 emissions and the global warming
37 See University of Oxford and Global Change Data Lab, Our World in Data, “CO₂ emissions” (available here).
38 See University of Oxford and Global Change Data Lab, Our World in Data, “CO₂ emissions” (available here).
16
they cause: each 1000 GtCO2 of cumulative CO2 emissions causes a 0.27°C to 0.63°C
temperature increase.39 This relationship has two important implications.
42. First, global temperature will stabilise at any level only when global anthropogenic
emissions reach “net zero”. That is, when the volume of GHG emissions going into the
atmosphere is balanced by an equivalent removal of GHG emissions from the
atmosphere. As long as the world does not reach “net zero”, the global temperature
will continue to increase, day by day.40
43. Second, the near-linear relationship between anthropogenic CO2 emissions and global
warming necessarily means that the world, as a whole, has only a limited carbon budget
left to stabilise the global temperature at any given level. The Remaining Carbon
Budget (“RCB”) is the net amount of CO2 that the world can still emit, collectively,
while keeping global warming below a particular temperature limit.
44. The RCB can be calculated for any particular temperature increase, with a given
probability. The IPCC has calculated RCBs for several temperature increases,
including 1.5°C.41 The Global Carbon Project, an international group of more than a
100 scientists, also regularly calculates and updates RCB figures, including for 1.5°C.42
45. The IPCC’s most recent calculations were done in 2021, with the IPCC’s Sixth
Assessment Report. At that time, the IPCC calculated that, to have a 50 percent chance
of limiting average warming to 1.5°C, the world had an RCB of approximately 500
GtCO2 from the beginning of 2020 (representing 17 percent of the total carbon budget)
(i.e., the “1.5°C RCB”).43 Using the RCB, the IPCC calculates emission reduction
pathways for each temperature level. Specifically, using the RCB, the IPCC determines
the percentage rate by which current emission levels must be reduced to hold the total
39 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), D.1.1.
40 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), D.1.1 and D.1.8.
41 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), p. 29.
42 Global Carbon project, “About GCP” (available here); see also, Pierre Friedlingstein et al., “Global Carbon
Budget 2023”, Earth System Science Data, 15(12), 5 December 2023 (available here), pp. 5301-5369.
43 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), Table SPM.2.
17
carbon budget and, hence, the temperature increase, to a given level (e.g., 1.5°C).
Antigua and Barbuda refers to these emission reduction targets as the “collective targets
aligned with the IPCC 1.5°C pathway”. Specifically, the IPCC found that, limiting
global warming to 1.5°C (with a 50 percent probability), requires global GHG emission
reductions (below the 2019 level) by 43 percent by 2030; by 60 percent by 2035; and,
by 84 percent by 2050.44 Net zero CO2 emissions need to be achieved by early 2050,
and net zero GHG emissions by early 2070.45 In other words, to hold global warming
to 1.5°C requires rapid, deep and sustained emission reductions.46
46. In 2023, subsequent to the IPCC’s Sixth Assessment, the Global Carbon Project
calculated the 1.5°C RCB, showing that it is now significantly lower; the RCB is now
vanishingly small.47 Indeed, the Global Carbon Project found that, from the beginning
of 2024, the RCB to limit global warming to 1.5° (with a 50 percent probability) is only
around 275 GtCO2, which is equal to around seven years of current CO2 emissions.48
In other words, the 1.5°C RCB from the beginning of 2024 is almost half of the 1.5°C
RCB from the beginning of 2020, as previously estimated by the IPCC. This means
that only 10 percent of the total carbon budget is left to limit global warming to 1.5°C.
This means that, at current emission levels, the remaining carbon budget to limit global
warming to 1.5°C would be entirely exhausted by January 2031.49
47. Figure 4, below, shows the most recent RCB calculated for 1.5°C by the IPCC and the
Global Carbon Project. The 1.5°C RCB is the red slice in the pie chart, with the
remainder of the pie reflecting historic emissions at the time of calculation.
44 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), Table SPM.1; UNFCCC, “Technical dialogue of the first global stocktake”,
UN Doc. FCCC/SB/2023/9, 8 September 2023 (available here) (hereinafter “UNFCCC, “Technical dialogue
of the first global stocktake” (2023)”), para. 98.
45 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), para. 98; IPCC, Sixth
Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Summary for Policymakers
(available here), C.2 and Table SPM.2.
46 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Summary for
Policymakers (available here), p. 17.
47 Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5304.
48 Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5345.
49 Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5304.
18
Figure 4: The total carbon budget to limit global warming to 1.5°C (Sources: IPCC &
Global Carbon Budget) 50
48. To limit global warming to 1.5°C, States must now, collectively, limit their emissions
to the amount represented by the red slice of pie. The red slice functions, therefore, as
a shared global resource that must be divided among States, consistent with their
obligations under international law. As Antigua and Barbuda explains below, this
requires that the 1.5°C RCB be divided equitably among States based on the principle
of fairness, equity and CBDR-RC.
C. The impact of anthropogenic GHG emissions on the environment and
human populations
49. Anthropogenic emissions leading to climate change are already causing severe, and in
some cases, irreversible, harm to the environment, with equally severe consequences
50 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), p. 29; and Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth
System Science Data, 15(12), 5 December 2023 (available here), p. 5327. The updated 1.5°C RCB by
Friedlingstein et al., is based on the IPCC Sixth Assessment Report and a recent revision of the IPCC estimates.
See, P. Forster et al., “Indicators of Global Climate Change 2022: Annual update of large-scale indicators of
the state of the climate system and human influence”, Earth System Science Data, 15(6) (2023) (available
here), pp. 2295-2327; R. Lamboll et al., “Assessing the size and uncertainty of remaining carbon budget”,
Nature Climate Change, 13, 8 June 2023 (available here), pp. 1360-1367.
Historical carbon budget
2400 ± 240 GtCO2
83%
Historical carbon budget
2550 ± 260 GtCO2
90%
19
for human populations.51 Antigua and Barbuda, for its part, has already suffered
considerable harms, i.e., loss and damage, and will continue to do so.
50. The IPCC has concluded, with “very high confidence”, that the “risks and projected
adverse impacts and related losses and damages from climate change will escalate
with every increment of global warming”.52 These harms are “higher for global
warming of 1.5°C than at present”;53 indeed, warming of 1.5°C is projected to cause
“unavoidable increases in multiple climate hazards and present multiple risks to
ecosystems and humans (very high confidence)”.54 These risks are “even higher at
2°C”.55 The harms caused by climate change differs substantially across States,
disproportionally affecting countries, such as SIDS, that are highly vulnerable to
climate hazards.56
51. In sub-section II.C.1, Antigua and Barbuda identifies the three key drivers of harm
resulting from anthropogenic GHG emissions: temperature increase, sea level rise and
ocean acidification. In sub-section II.C.2, Antigua and Barbuda addresses the knockon
harms to human populations. Antigua and Barbuda describes these harms from a
global perspective – since they are occurring globally – with a particular focus on the
special vulnerability of SIDS, including Antigua and Barbuda.
52. These harms are extreme, interrelated and reinforcing. The harms caused in one
instance amplify and drive other harms caused, and vice-versa. The harms are too
extensive to be summarised comprehensively in this Written Statement (an exercise, in
51 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), para. B.1.
52 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.2.2.
53 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.2.2.
54 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), para. B.3; see also, Caribbean Climate Science Report, March 2024 (Annex
1), p. 22.
55 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.2.2; Caribbean Climate Science Report, March 2024 (Annex 1), p. 22.
56 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), para. B.2.4; see also, Caribbean Climate Science Report, March 2024
(Annex 1), p. 17.
20
any event, already conducted by IPCC and IPBES experts).57 Instead, Antigua and
Barbuda provides a brief overview of the damage resulting from anthropogenic GHG
emissions, based on international scientific consensus, to provide a solid factual basis
for the subsequent legal arguments.
1. The key drivers of harm: temperature increase, sea level rise and
ocean acidification
53. There are three immediate consequences of anthropogenic GHG emissions that drive
harm to the environment and human populations: temperature increase, sea level rise,
and ocean acidification. Antigua and Barbuda unpacks below the causal connection
between anthropogenic emissions and these three drivers.
a. Temperature increase
54. As anthropogenic GHGs cause the Earth’s atmosphere to warm, land surface
temperatures and ocean temperatures also increase. Antigua and Barbuda addresses
each in turn.
i. Land temperature
55. Climate change resulting from anthropogenic GHG emissions causes rising
temperatures across land territories.58 Global land surface temperature has increased
faster since 1970 than in any other 50-year period over at least the last 2000 years.59
Temperatures during 2011-2020 were collectively the warmest in around 6500 years.60
The summer of 2023 was the hottest on record.61 It is “virtually certain” that the
57 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here); see also, IPBES, 2019, Global Assessment Report on Biodiversity and
Ecosystem Services, Summary for Policymakers (available here).
58 This includes statistically significant warming in the Caribbean region; see, Caribbean Climate Science Report,
March 2024 (Annex 1), p. 13.
59 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), para. A.2.2.
60 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), para. A.2.2.
61 See, Financial Times, “Climate Graphic of the Week: Critical 1.5C threshold breached over 12-month period
for first time”, 8 February 2024 (available here); see also, Copernicus, “Global Climate Highlights 2023: 2023
is the hottest year on record with global temperatures close to the 1.5°C limit” (available here); Berkeley Earth
“Global Temperature Report for 2023”, 12 January 2024 (available here).
21
frequency, intensity and duration of heatwaves will increase with each increment of
warming beyond pre-industrial levels.62
Figure 5: Global surface air temperature (Source: Copernicus Global Climate
Highlights 2023)
62 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), para. A.3.1.
22
Figure 6: Daily global temperature increase above pre-industrial level (1850-1900) in
2023 (Source: Copernicus Global Climate Highlights 2023)
56. Temperature increases vary across regions; some are more affected than others. African
countries, for example, are expected to experience unprecedented high temperatures
much earlier than the generally wealthier, higher latitude countries.63
57. Increases in global temperatures come with a swathe of harmful consequences, most
obviously melting sea ice, heatwaves, drought and wildfires, but also disruptions to the
Earth’s water cycle and seasonal weather patterns more generally. These consequences
have, themselves, knock-on and interacting effects on the environment, and on human
populations, as developed in the sub-sections below.
ii. Ocean temperature
58. The world’s oceans have “mammoth” heat trapping ability – oceans have already
absorbed around 93 percent of the excess heat generated from anthropogenic GHG
emissions.64 Ocean temperatures in the warmest and coolest months of the year have
63 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 1320.
64 IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
Part B (available here), p. 1664 (“The Ocean has absorbed 93% of the extra heat arising from the enhanced
greenhouse effect”); The Guardian, “Oceans have been absorbing the world’s extra heat. But there’s a huge
payback”, 14 May 2023 (available here); United Nations, “The ocean – world’s greatest ally against climate
change” (available here); NASA, “Ocean Warming” (available here).
23
increased, in most regions, since 1950.65 In 2023, sea surface temperatures across the
globe smashed virtually all existing records, and this trend continues into 2024.66
59. Ocean temperature increase is particularly dangerous because oceans play a key role in
regulating the climate system as a whole. The ability of the oceans to absorb CO2 and
atmospheric heat alleviates some of the impact of climate change on land, with oceans
capturing around 30 percent of CO2 emissions released in the atmosphere, and around
90 percent of excess atmospheric heat.67 But as the ocean gets hotter, the ability to
absorb CO2 and heat diminishes, in turn resulting in more global warming.
60. This vicious cycle is getting worse over time, with the ocean getting hotter at a faster
rate.68 Indeed, analysis of isotherms, which measure temperature increase over time,
shows the rate of ocean warming is increasing.69
61. Increased ocean temperatures, like land temperatures, drive a myriad of other
environmental and human harms, not least rising sea levels – itself a key driver of harm.
The acceleration in ocean warming also ramps up the speed at which populations must
either move or adapt to survive.70 Marine heatwaves – periods of extremely high ocean
temperatures – have already negatively affected marine organisms and ecosystems in
all ocean basins over the last two decades, including critical “foundation species” such
as corals, seagrass and kelp forests.71
65 IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
Part B (available here), p. 1664.
66 The Guardian, “Record ocean temperatures put Earth in ‘unchartered territory’, say scientists”, 26 April 2023
(available here); BBC, “Ocean heat record broken, with grim implications for the planet”, 4 August 2023
(available here); Africa News, “EU scientists say ocean surface temperatures reach record high in February
[2024]”, 8 March 2024 (available here); Bloomberg, “Record-Smashing Heat in the World’s Oceans,
Explained”, 4 March 2024 (available here); Lijing Cheng et al., “New Record Ocean Temperatures and
Related Climate Indicators in 2023”, Advances in Atmospheric Sciences, 11 January 2024 (available here).
67 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 456.
68 IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full
Report Part B (available here), Table 30-1, p. 1667.
69 IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
Part B (available here), Table 30-1, Table 30-3, and p. 1677.
70 IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
Part B (available here), p. 1667.
71 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 67.
24
62. Increased ocean temperatures also cause ocean deoxygenation: warm water holds less
oxygen than cold water, so as the ocean absorbs heat from the atmosphere, its overall
oxygen content decreases.72 Like humans and other animals, fish and other aquatic
organisms need oxygen to breathe. With insufficient oxygen, aquatic creatures become
physically stressed, reproduction is impaired, growth rates slow, and they become more
susceptible to disease and predation.73 Oxygen levels have already decreased by around
two percent since the 1950s,74 and it is “virtually certain” that risks from deoxygenation
will increase with every increment of additional warming.75
63. Increased ocean temperatures also disrupt “ocean stratification”, i.e., the natural
separation of the ocean into layers, which in turn hinders the movement of nutrients to
the water’s surface, and the movement of oxygen to deep ocean layers. This, combined
with other key drivers, further disrupts the thermohaline circulation system, or “global
conveyor belt” – the complex system of ocean currents that circulate essential heat,
nutrients and oxygen around the Earth’s oceans, and helps regulate the Earth’s climate
system writ large. Latest research (i.e., post-dating the IPCC’s Sixth Assessment
Report), using new early warning systems, indicates that Atlantic Ocean current
systems are nearing “collapse”.76 This would be a critical climate “tipping point” (i.e.,
a threshold point which triggers large-scale, rapid, and irreversible changes to the
climate system as a whole).77
64. As unpacked below, this large-scale disruption to habitats and ecosystems has severe
consequences for ocean biodiversity and the human populations that rely on it.
b. Sea level rise
65. A second major driver of environment and human harm caused by anthropogenic GHG
emissions is sea level rise.
72 IUCN, “Ocean Deoxygenation”, December 2019 (available here).
73 IUCN, “Ocean Deoxygenation”, December 2019 (available here).
74 IUCN, “Ocean Deoxygenation”, December 2019 (available here).
75 IPCC, 2018, Special Report on Global Warming of 1.5°C, Full Report (available here), p. 224.
76 René M. Van Westen, Michael Kliphuis and Henk A. Dijkstra, “Physics-based early warning signal shows
that AMOC is on tipping course”, Sciences Advances, 10(6) (2024) (available here); LA Times, “Researchers
Warn of a Catastrophic Collapse of Ocean Currents”, 26 February 2024 (available here).
77 See, footnote 76, above.
25
66. It is “virtually certain” that global mean sea level attributable to anthropogenic GHG
emissions is rising, and that the rate of sea level rise is accelerating.78 Anthropogenic
GHG emissions leading to climate change causes sea level rise in two ways. First,
warmer temperatures cause ice sheets, icebergs and mountain glaciers to melt, adding
additional fresh water to the ocean.79 Second, as the ocean absorbs more heat it
becomes less dense, and expands physically (“thermal expansion”).80
67. The overall degree of sea level rise is “strongly dependent” on which emission scenario
is used in the modelling, i.e., the extent of mitigation actions in the coming decades.81
The rate of sea level rise is already accelerating, and will continue to do so up to 1.5°C.82
Global mean sea level rise is projected to be around 0.1m higher with a warming of 2°C
compared to 1.5°C,83 amounting to approximately 10 million more people exposed to
related risks.84
68. It is “virtually certain” that continued emissions will further global mean sea level rise.85
Moreover, extreme sea level events “that occurred once per century in the recent past
are projected to occur at least annually at more than half of all tide gauge locations by
2100”.86 Caribbean islands are among those projected to suffer the most loss of
territory; as between 1m to 6m of sea level rise, approximately 9 to 50 percent of
78 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 55.
79 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 326.
80 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 326.
81 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 55.
82 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), pp. 55-56: “[Sea level rise] at the end of the century is projected to be faster under all
scenarios”.
83 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here),
para. B.2.
84 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here),
para. B.2.1. See further on risks to human populations in sub-section II.C.3.
85 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.1.3.
86 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report (available
here), p. 77.
26
Caribbean islands will be entirely submerged.87 The loss of territory for Barbuda
resulting from different levels of sea level rise is depicted in the Figure 7 below.
Figure 7: Loss of territory for Barbuda resulting from sea level rise (Source: Climate
Central Mapping)
For a sea-level rise of 1m For a sea-level rise of 3m
69. Projections of sea level rise also involve an assessment of “tipping points”, one of which
is the melting of the Greenland and West Antarctic sheets, associated with an
irreversible sea level rise of several metres over the next two centuries.88 While there is
uncertainty around the triggering temperature range for this event, current research
estimates full-scale, irreversible melting at somewhere between 1.5°C and 2°C.89
87 Caribbean Climate Science Report, March 2024 (Annex 1), p. 4.
88 IPCC, 2018, Special Report on Global Warming of 1.5°C, Full Report (available here), p. 257.
89 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here),
para. B.2.2.
27
70. Sea level rise causes destruction to coastal ecosystems and infrastructure, including to
community livelihoods, agriculture and habitability.90 Of course, these impacts are not
felt uniformly. By their nature – bounded by ocean and small in territory – SIDS are
uniquely vulnerable.91 In a 1.5°C warming scenario, the amount of territory expected
to be subject to flooding will more than triple for all SIDS.92 This means that for SIDS,
sea level rise is indisputably an existential threat.93
71. Urban atoll islands are already expected to experience moderate to high risk of erosion,
inundation and salination due to sea level rise (including, for some islands, total
disappearance), and will continue to face greater risks even under a low emission
pathway. Under a high emission pathway, that risk increases to “high” for “all lowlying
coastal settings”.94
c. Ocean acidification
72. Ocean acidification is caused specifically by CO2 emissions (as opposed to the other
types of GHGs). When CO2 is absorbed into the ocean, it increases the concentration
of hydrogen ions in the water and lowers the ocean’s pH levels, increasing acidity.95
73. Approximately 30 percent of the CO2 released into the atmosphere each year is
absorbed into the ocean; it is “virtually certain” that ocean surface pH has already
declined over the past four decades.96 Increased acidity in the water interferes with the
physical development of marine life in a variety of ways, compromising their ability to
90 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 55.
91 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), pp. 2050-2053 and pp. 2053-2063.
92 Michalis I. Vousdoukas et al., “Small Island Developing States under threat by rising seas even in a 1.5°C
warming world”, Nature Sustainability, 6 (2023) (available here), pp. 1552-1564.
93 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), para. B.4.5.
94 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 56.
95 IPCC, Fourth Assessment Report, 2007, The Physical Science Basis (Working Group I), Full Report (available
here), p. 714.
96 IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
Part B (available here), p. 1673; IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability
(Working Group II), Full Report (available here), Table 3.2.
28
find food and detect predators.97 Acidification rates caused by GHG emissions
associated with 1.5°C warming would negatively impact a wide range of marine
ecosystems, aquaculture fisheries, worsening considerably as temperatures rise towards
2°C,98 and compounding other drivers of harm.
2. How anthropogenic GHG emissions harm the environment
a. Extreme weather events
74. Anthropogenic GHG emissions cause large-scale disruptions to the Earth’s climate
system, resulting in more frequent, and more extreme, weather events.99 It is intuitive
that climate change causes an increase in extreme heat waves, droughts and wildfires.
However, it also disrupts, among others, the planet’s water cycle, as higher land and
ocean temperatures mean more water is evaporated into the atmosphere than would
otherwise be the case.
75. Depending on the region, this leads to more intense hurricanes and storms (since storm
systems draw their energy from warm atmospheric water vapor); higher precipitation
and therefore flooding and, counterintuitively, more severe winters (since trapped
atmospheric water vapor leads to heavier snowfall).100
76. These are not purely theoretical conclusions. Since the IPCC’s Fifth Assessment Report
in 2014, there has been an observable increase in such weather events, with scientific
consensus that the increase is attributable to warming caused by anthropogenic GHG
emissions.101 The WMO has concluded that such events are “the new norm”.102
97 See, The One UN Climate Change Learning Partnership, “Ocean Acidification: A Summary for Policymakers
from the Second Symposium on the Ocean in a High CO2 World” (available here), p. 5.
98 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.1.3.
99 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 45.
100 EarthJustice, “How Climate Change is Fueling Extreme Weather”, 19 July 2023 (available here); see also,
IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 45; IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group
I), Technical Summary (available here), pp. 82-86.
101 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 45.
102 World Meteorological Organization, “Extreme weather is the ‘new norm’” 22 August 2023 (available here).
29
Extreme weather causes “widespread, pervasive impacts to ecosystems, people,
settlements, and infrastructure”.103
77. Moreover, changes in extremes continue to become larger with every additional
increment of warming.104 For example, the intensity and frequency of extreme
heatwaves, heavy precipitation, agricultural and ecological droughts will discernibly
increase with every additional 0.5°C of global warming.105 Periods of extreme heat
have already caused mass species mortality on both land and in the ocean.106 Such
“unprecedented” events will occur increasingly with additional global warming, even
if limited at 1.5°C.107
78. Due to their geography, SIDS are unusually vulnerable to such disruptions to ocean
circulation systems, experiencing, for example, high variation (even without climate
disruptions) in annual rainfall.108 Along with heightened exposure to sea level rise, this
makes SIDS especially vulnerable to climate-induced extreme weather, in particular the
increased severity of tropical cyclones, storm surges, droughts and changing rainfall
patterns.109
79. Antigua and Barbuda is already experiencing a significant uptick in dangerous extreme
weather events, such as Hurricane Irma in 2017, extreme rainfall throughout November
2020, Tropical Storm Phillipe and Hurricane Tammy in 2023.
b. Coastal erosion, inundation and salinization
80. Sea level rise caused by global warming results in coastal erosion (the disappearance
of land through the erosive effects of the rising sea levels and weathering) and
103 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), para. B.1.1.
104 IPCC, Sixth Assessment Report, 2021, The Physical Scientific Basis (Working Group I), Summary for
Policymakers (available here), para. B.2.2.
105 IPCC, Sixth Assessment Report, 2021, The Physical Scientific Basis (Working Group I), Summary for
Policymakers (available here), para. B.2.2.
106 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. A.2.3.
107 IPCC, Sixth Assessment Report, 2021, The Physical Scientific Basis (Working Group I), Summary for
Policymakers (available here), para. B.2.2.
108 UNFCCC, 2005, Climate Change and Small Island Developing States (available here), p. 14.
109 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 2045; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 19 and 25.
30
inundation (the covering of normally dry land with water). Sea level rise also results
in saline intrusion, i.e., the movement of saltwater into freshwater aquifers,
compromising sources of drinking water and soil quality.110
81. In the absence of “major additional adaptation efforts”, the risk of erosion, inundation
and salination is expected to “significantly increase” by the end of this century along
all low-lying coasts.111 Large-scale coastal erosion and inundation – for obvious
reasons – threatens ecologically important coastal and estuarine ecosystems, such as
saltmarshes, mangroves, vegetated dunes and wetlands.112 Coastal ecosystems –
already vulnerable to other climate-related disruptions – are expected to experience
severe biodiversity loss over the course of the century.113 The consequences for
agriculture and food security (among others) are discussed further in the next section.
82. Coastal erosion and inundation also mean that historically rare “extreme sea level”
events – triggered by a combination of storm surges, tides and waves – will become
“common” by 2100 under all scenarios modelled by the IPCC.114 Many low-lying
cities and small islands, at most latitudes, will experience these events annually by
2050.115
c. Habitat and biodiversity loss
83. Severe habitat and biodiversity loss is the ultimate consequence of every driver of harm
associated with anthropogenic GHG emissions. As a result of existing levels of
warming, biodiversity is “declining faster than at any time in human history”.116
Climate change has already altered terrestrial, marine and freshwater ecosystems all
around the world, including the first climate-driven extinctions.117 These alterations
110 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 611.
111 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary
(available here), p. 56; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 16 and 29.
112 IPCC, 2019, Special Report on the Ocean and Cryosphere, Technical Summary (available here), p. 55.
113 IPCC, 2019, Special Report on the Ocean and Cryosphere, Technical Summary (available here), p. 56.
114 See, footnote 113, above.
115 See, footnote 113, above.
116 IPBES, 2019, Global Assessment Report on Biodiversity and Ecosystem Services (available here), p. xiv.
117 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 45; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 15
and 26-27.
31
are “approaching irreversibility”.118 Risks to ecosystem integrity, functioning and
resilience are projected to escalate “with every tenth of a degree increase in global
warming (very high confidence)”.119 Below, Antigua and Barbuda unpacks some of
these consequences, focusing first on terrestrial biodiversity and second on marine
biodiversity.
i. Land biodiversity
84. The IPCC’s Sixth Assessment Report found that terrestrial ecosystem deterioration
resulting from climate change has occurred earlier and is more widespread than first
anticipated.120 For thousands of species across the world, destruction of ecosystems
means increased rates of disease, mass mortality events, and – irreversibly –
extinction.121 Already, nearly half of threatened terrestrial mammals, and a quarter of
threatened birds are experiencing negative effects from current levels of post-industrial
warming.122
85. The IPCC and IPBES have both concluded that land-based biodiversity loss and
degradation will continue to escalate across the globe with every increment of global
warming.123 As between 1.5°C and 2°C, the majority of terrestrial species ranges are
projected to “shrink dramatically”.124 At approximately 4°C, nearly 16 percent of
studied terrestrial species are expected to go extinct.125
86. The biodiversity of SIDS is a particular concern. Despite making up only 2 percent of
the Earth’s terrestrial surface, islands are remarkably biodiverse, home to around 25
118 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. A.2.3.
119 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 55.
120 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 45.
121 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), p. 9.
122 IPBES, 2019, Global Assessment Report on Biodiversity and Ecosystem Services (available here), p. XXXIII.
123 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), p. 14; IPBES, 2019, Global Assessment Report on Biodiversity and
Ecosystem Services (available here), p. XXVIII.
124 IPBES, 2019, Global Assessment Report on Biodiversity and Ecosystem Services (available here), p. XX.
125 See, footnote 124, above.
32
percent global flora species, 12 percent of bird species and 10 percent of mammal
species.126 Islands also host nearly half the world’s critically endangered species.127 In
short, when the biodiversity of SIDS is threatened, global biodiversity writ large is
threatened.128 New studies forecast that small islands are likely to experience some of
the largest increases in endemic extinctions as a result of climate change, substantially
contributing to future global biodiversity loss.129
87. Of particular note, a changing climate creates new ecological niches that leave landbased
ecosystems especially vulnerable to invasive species – already a significant
problem for SIDS.130 For example, since 2011, Antigua and Barbuda has been severely
affected by Sargassum seaweed.131 A highly invasive species, the increasing abundance
of Sargassum in the Caribbean Sea (and elsewhere) is largely attributable to higher sea
surface temperatures.132 Sargassum has well-documented negative ecological effects,
has substantially disrupted beach tourism in the Caribbean, and has imposed millions
of dollars in clean-up costs annually on affected beaches.133
ii. Ocean biodiversity
88. The habitats and biodiversity of the world’s oceans are faring no better. Warming
waters, deoxygenation, sea level rise and ocean acidification are, already, interacting to
place unprecedented stress on ocean ecosystems, disrupting the migratory patterns,
predation activities and reproductive processes of species ranging from phytoplankton
126 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 2060.
127 See, footnote 126, above.
128 See, footnote 126, above; see also, Caribbean Climate Science Report, March 2024 (Annex 1), p. 27.
129 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 2046; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 15 and 26-
27.
130 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), pp. 200, 205 and 208; IPBES, Thematic Assessment Report, 2023, Invasive Alien Species
Assessment, Summary for Policymakers (available here), pp. 21-22.
131 Caribbean Climate Science Report, March 2024 (Annex 1), p. 15; see, Western Atlantic Fishery Commission,
“Impacts of Sargassum on marine resources in the region and utilization of initiatives”, September 2023
(available here).
132 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 467.
133 See, footnote 132, above; see also, Caribbean Climate Science Report, March 2024 (Annex 1), p. 15.
33
to marine mammals.134 For each affected species, there are knock-on effects throughout
the whole ecosystem.135 Each trend becomes “more pronounced” as temperatures
increase yet further.136
89. There has, as a result, been an average decrease in the population replenishment of
fisheries stocks of approximately 3 percent per decade over the course of the 20th
century.137 These warming-induced changes in the special distribution and abundance
of fish stocks have already challenged the management of biologically and
economically significant fisheries.138 It thus goes without saying, that “limiting global
warming to 1.5°C is projected to reduce risks to marine biodiversity, fisheries, and
ecosystems”.139
90. Of the many thousands of marine species threatened by climate change, coral reefs
deserve particular attention. Coral reefs have enormous ecological, cultural and
economic importance.140 They are among the most diverse and valuable ecosystems
on Earth, supporting more species per unit area than any other marine environment.141
They form natural barriers protecting coastlines from waves, storms and floods, and
provide stability for other crucial biodiverse coastal ecosystems like mangroves and
seagrass beds.142 They are of profound importance to many SIDS, including Antigua
and Barbuda, as an indispensable source of food, cultural life, and economic value.
91. Coral reefs are also profoundly susceptible to the effects of climate change. In 2022,
the IPCC’s Sixth Assessment Report concluded that mass coral bleaching and mortality
134 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), pp. 450-451.
135 C. Mackenzie et al., “Ocean Warming, More than Acidification, Reduces Shell Strength in a Commercial
Shellfish Species during Food Limitation”, PLOS one 9 (2014) (available here), p. 2.
136 IPCC, 2018, Special Report on Global Warming of 1.5°C, Full Report (available here) p. 222.
137 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 451.
138 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 451.
139 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here),
para. B.4.
140 See, Global Fund for Coral Reefs, “2022 Action Report” (available here), p. 1.
141 See, IPCC, Fifth Assessment Report, 2014, Impacts, Adaptation and Vulnerability (Working Group II), Full
Report Part A (available here), p. 97.
142 See, footnote 141, above.
34
was already “the most widespread and conspicuous impact of climate change”.143
Because coral reefs have such a narrow temperature tolerance, they are susceptible to
even small increases in ocean temperatures. Already experiencing severe decline, at
1.5°C of warming, coral reefs are expected to decline by a further 70-90 percent.144 At
2°C of warming, decline is expected to reach 99 percent.145 Put simply: coral reefs, and
their myriad attendant benefits, will disappear.146
3. How anthropogenic GHG emissions harm human populations
92. In this section, Antigua and Barbuda unpacks the harms to human populations caused
by anthropogenic emissions. Around 3.3 billion people are living in countries with high
vulnerability to climate change.147 The harms to human populations flow directly from
the key drivers, especially temperature increase and sea level rise; as well as indirectly
from damage to the environment, i.e., from extreme weather events, coastal erosion,
inundation and salinisation, and biodiversity loss.
93. Moreover, these widespread harmful impacts will disproportionally affect those
vulnerable communities “who have historically contributed the least to current climate
change”.148 Some of these harmful impacts are irreversible and their likelihood, and
severity, increases with every increment of warming.149
a. Full or partial loss of territory
94. Coastal erosion and inundation caused by global-warming induced sea level rise and
extreme weather events results in the outright disappearance of States’ territory,
143 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 413.
144 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here) p. 8;
see also, Caribbean Climate Science Report, March 2024 (Annex 1), p. 26.
145 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here), p. 8.
146 The Guardian, “‘Huge’ coral bleaching unfolds across the Americas prompt fears of global tragedy”,
11 August 2023 (available here); The Guardian, “Fifth mass coral bleaching event in eight years hits Great
Barrier Reef, marine park authority confirms”, 8 March 2024 (available here); Reuters, “World on brink of
fourth mass coral reach bleaching event”, 5 March 2024 (available here).
147 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 52.
148 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. A.2.
149 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.3.
35
including land currently occupied by human settlements, and key infrastructure like
port and transport services.
95. Kiribati – a nation of 12,000 people, comprised of 33 coral atolls distributed across the
Pacific Ocean – is frequently cited as the first State that will be rendered permanently
uninhabitable if sea levels continue to rise.150 Some of its islands have already
effectively disappeared.151
96. Thus, for SIDS, the threat posed by coastal erosion and inundation is literally
“existential”.152 Small islands will faced reduced habitability even below 1.5°C.153
Island settlements are typically concentrated along coastlines, exposing decades of
high-density urban development to multiple climate-related hazards.154 The “vast
majority” of low-lying islands and coastal regions face “substantial risk” to territory;155
for example, based on current sea level rise projections, almost all port and harbour
facilities in the Caribbean will suffer inundation in the future.156
150 The Guardian, “‘No safe place’: Kiribati seeks donors to raise islands from encroaching seas”, 18 November
2022 (available here).
151 See, footnote 150, above.
152 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Summary
for Policymakers (available here), para. B.4.5.
153 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here) p. 2046; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 29-30.
154 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), pp. 2045-2047.
155 IPCC, 2019, Special Report on the Ocean and Cryosphere in a Changing Climate, Full Report (available
here), p. 328.
156 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 2064; see also, Caribbean Climate Science Report, March 2024 (Annex 1), p. 30.
36
Figure 8: Populations living in small islands that may be exposed to coastal inundation by 2100 under RCP 4.5 (Source: IPCC)
37
b. Harm to human physical and mental health
97. Climate change has “already harmed human physical and mental health”.157 Under a
high emissions scenario, over nine million climate-related deaths per year are projected
by the end of the century,158 with tens of thousands of deaths from heat-related
morbidity alone.159 Each additional unit of warming will increase heat-related
morbidity and mortality.160 For countries “highly vulnerable” to climate change – like
SIDS – observed mortality from floods, drought and storms alone was 15 times higher
in the last decade than for less vulnerable countries.161
98. Climate change has already contributed to malnutrition and disease susceptibility,
especially for women, children, low-income households and Indigenous Peoples.162
Moreover, reductions in projected food availability are larger at 2°C than at 1.5°C.163
Climate-related food safety risks have increased globally, as has the transmission of
vector-, water- and food-borne diseases.164 Disruptions to ecosystems give increased
opportunities for pathogens to spread from wildlife to human populations, increasing
emergence of zoonotic disease epidemics.165 As just one example: higher global
temperatures are already increasing the geographic distribution of mosquito-borne
diseases like dengue fever, malaria, and the Zika virus.166
157 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 50.
158 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 63.
159 See, footnote 158, above.
160 IPCC, 2018, Special Report on Global Warming of 1.5°C, Full Report (available here), p. 241.
161 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 50; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 30-
31.
162 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 51.
163 IPCC, 2018, Special Report on Global Warming of 1.5°C, Summary for Policymakers (available here), p. 11.
164 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 51.
165 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 51.
166 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 1062; see also, Caribbean Climate Science Report, March 2024 (Annex 1), pp. 30-31.
38
99. Mental health impacts are also increasing, brought on by exposure to extreme weather
events, displacement, famine, loss of cultural practices and traditional ways of life, as
well as anxiety and grief about climate change.167
c. Compromised access to food and water
100. Climate change is already stressing the world’s food production systems, with negative
consequences for the livelihoods, food security and nutrition of hundreds of millions of
people.168 Climate-related extremes have compromised the productivity of all
agricultural and fishery sectors, with particularly acute and severe impacts for people
living in sub-Saharan Africa, Asia, small islands, and Central and South America.169
Adverse impacts on food security will worsen with every increment of warming.170
Indeed, even warming below 1.5°C is predicted to result in a reduction in the range of
available crops in certain regions, including the Caribbean.171
101. Water-related risks, including drought and associated social risks, also increase with
every increment of warming.172 With warming of 4°C, up to 4 billion people are
predicted to experience water scarcity – potentially over half the world’s population.173
Small islands are especially vulnerable to water scarcity, since they rely on groundwater
sources prone to salinisation from sea level rise.174 For small island regions, freshwater
resource stress would be 25 percent higher at 2°C compared to 1.5°C.175
167 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 63.
168 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 44.
169 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 49.
170 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 57.
171 See, Caribbean Climate Science Report, March 2024 (Annex 1), p. 28 (“Crop suitability modelling on several
commercially important crops grown in Jamaica found that even an increase of less than 1.5°C could result in
a reduction in the range of crops that farmers may grow”).
172 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 61.
173 See, footnote 172, above.
174 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Full Report
(available here), p. 14, B.4.2, and pp. 2095-2096.
175 See, Caribbean Climate Science Report, March 2024 (Annex 1), p. 28.
39
d. Damage to cities, settlements and infrastructure
102. Climate change is already affecting every inhabited region across the globe.176 With
further warming, “every region is projected to increasingly experience concurrent and
multiple changes in climatic impact-drivers”.177 Human settlements and infrastructure
are experiencing cascading climate-related risks, from, among others, sea level rise,
heatwaves, droughts, floods, wildfires and permafrost thaw.178 These cause disruption
to key infrastructure and services such as energy supply, communications, food and
water supply and transport systems,179 with the brunt of damage felt by the most
economically and socially marginalised populations.180
103. These risks will continue to increase with each increment of warming.181 For example:
even under a “moderate” emissions scenario, by 2050 in Europe, permafrost thaw in
the pan-Arctic is expected to impact nearly 70 percent of infrastructure, more than 1200
settlements, and four million people.182 Under a high emissions scenario, risks to critical
infrastructure in many cities becomes “severe and pervasive”.183
104. For coastal cities and settlements in particular, climate-driven risks to people and
infrastructure are “already high and will get progressively worse over the 21st century
176 IPCC, Sixth Assessment Report, 2021, The Physical Scientific Basis (Working Group I), Summary for
Policymakers (available here), para. A.3; Caribbean Climate Science Report, March 2024 (Annex 1), pp. 16-
17 and 27-28.
177 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.1.4.
178 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 53.
179 See, footnote 178, above.
180 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 50.
181 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. B.2.2.
182 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 66.
183 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 113.
40
and beyond”.184 While well-designed coastal protection is highly effectively in
reducing expected damage, it is frequently unaffordable for rural and poorer areas.185
e. Forced migration and displacement
105. Under all predicted emissions scenarios, some regions that are currently densely
populated will become unsafe or uninhabitable over time.186 Inevitably, populations
will be forced to migrate, and will suffer displacement. From sea level rise alone –
which increases with every increment of warming – the projected number of people
potentially at risk of future displacement ranges from tens of millions to hundreds of
millions by the end of this century.187
D. Efforts to address climate change
106. Despite the severe harms caused by climate change (including loss and damage already
experienced by Antigua and Barbuda), and despite understanding the need for urgent
action, States still fail to address climate change effectively (D.1). They do so despite
the presence of concrete policy options which are available to tackle climate change
effectively (D.2).
1. States are failing to effectively address climate change
107. For decades, States have understood the adverse impact of human activity on climate
change, the severe harm caused by climate change, and, accordingly, the need to take
effective action to combat climate change. Yet, as a factual matter, States’ efforts to do
so have, thus far, been limited and insufficient.
108. This conclusion is clear from the COP Global Stocktake Decision, which, every five
years, assesses progress on meeting the Paris Agreement’s goals.188 The technical
dialogue of the COP Global Stocktake was released in September 2023, and concluded
that States’ current efforts to combat climate change, and its associated harms, are
184 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 66.
185 See, Caribbean Climate Science Report, March 2024 (Annex 1), p. 29.
186 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 64.
187 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 65.
188 Paris Agreement, Article 14.
41
falling woefully short – with regard to mitigation, adaptation, and financing.189 The
COP Global Stocktake Decision itself confirms this and underscores that “Parties are
not yet collectively on track towards achieving the purpose of the Paris Agreement and
its long-term goals”.190
109. First, with regard to mitigation, global emissions to date are “not in line with modelled
global mitigation pathways consistent with the global temperature goal of the Paris
Agreement, nor are they aligned with longer-term emission reduction goals”.191
110. The objective of the UNFCCC, established in 1992, is the “stabilization of greenhouse
gas concentrations in the atmosphere at a level that would prevent dangerous
anthropogenic interference with the climate system”.192 To contribute to that objective,
the Paris Agreement of 2015 defined the following temperature goal: “holding the
increase in the global average temperature to well below 2°C above pre-industrial
levels and pursuing efforts to limit the temperature increase to 1.5°C above preindustrial
levels”.193 This temperature goal was a product of fierce negotiation and
compromise.194 It was based on contemporary IPCC assessments as to what
temperature levels would avoid the most catastrophic human and environmental
consequences. Crucially, however, it was not based on holding global warming to a
level that would prevent significant environmental and human harm. As is clear from
the preceding section, and the recent work from the IPCC, such harms are already
occurring, at current average warming levels of 1.1°C – 1.35°C.
111. The COP Global Stocktake Decision of December 2023 identifies gaps in both the
ambition and the implementation of States’ so-called “nationally determined
189 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), paras. 9, 29 and 48.
190 UNFCCC COP, Draft decision -/CMA.5: “Outcome of the first global stocktake” UN Doc.
FCCC/PA/CMA/2023/L.17, 13 December 2023 (available here) (hereinafter “UNFCCC COP, Draft
Decision -/CMA.5, “Outcome of the first global stocktake” (2023)”).
191 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 13 (emphasis added).
192 UNFCCC, Article 2.
193 Paris Agreement, Article 2.1(a).
194 See, Navraj Singh Ghaleigh, “Article 2: Aims, Objectives and Principles” in Geert van Calster and Leonie
Reins (eds.), The Paris Agreement on Climate Change (Elgar Publishing Commentaries, 2021), p. 78; see
also, The Guardian, “Climate coalition breaks cover in Paris to push for binding and ambitious deal”,
8 December 2015; The Washington Post, “How tiny islands drove huge ambition at the Paris climate talks”,
12 December 2015 (available here).
42
contribution”, or “NDC”, to meet the Paris temperature goal.195 That is, the technical
dialogue of the COP Global Stocktake identifies:
(a) Lack of NDC ambition: the mitigation ambition of NDCs is not collectively
sufficient to achieve the Paris temperature goal.196 In other words, even taking
current NDCs on their face, assuming perfect implementation, the volume of
proposed reductions still place 1.5°C out of reach; and make 2°C harder after
2030.197
(b) Lack of NDC implementation: even for the current NDCs lacking ambition,
implementation of the NDCs is, in fact, lagging behind; currently stated policies
and actions fall short of reaching stated targets and pledges.198
112. In sum, “action is needed” to bridge both ambition and implementation gaps.199
113. The COP Global Stocktake Decision, therefore, confirms as a factual matter that States
have, to date, failed to take effective action to prevent significant harm resulting from
the impact of anthropogenic emissions on the climate system. As States are undertaking
insufficient action to meet the Paris Agreement temperature goal, their actions are
certainly insufficient to prevent significant harm, which occurs already at lower
temperatures.
114. Second, the technical dialogue of the COP Global Stocktake also found serious gaps in
adaptation measures, as well as measures to address loss and damage already occurring
from climate change. Most observed adaptation efforts are “fragmented, incremental,
sector-specific and unequally distributed across regions”.200 There is “a rapidly closing
195 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 94.
196 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p.16.
197 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Technical
Summary (available here), p. 70.
198 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 16; IPCC, Sixth
Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Summary for Policymakers
(available here), p. 14.
199 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 16. See also, UNFCCC
COP, “Draft decision -/CMA.5: Outcome of the first global stocktake” (2023) (available here), paras. 63 and
94.
200 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 7.
43
window” as regards adaptation measures “to secure a liveable and sustainable future
for all”.201
115. Third, as regards financing, the technical dialogue of the COP Global Stocktake also
addressed the gap between pledged and realised financing for developing countries’
mitigation and adaptation efforts, and to address loss and damage. The technical
dialogue confirmed that these gaps remain significant.202 Subsequent to the Paris
Agreement, the Parties agreed to mobilise 100 billion United States Dollar (“USD”) per
year to address the climate-related needs of developing countries.203 Developed
countries have consistently failed to meet the target, with the Parties – repeatedly –
expressing “deep regret” and “serious concern” at the state of climate financing, and
“urging” developed countries to increase their efforts.204 Moreover, the Technical
Dialogue of the COP Global Stocktake stated that financing and support for adaptation,
as well as loss and damage, “need to be rapidly scaled up”, to meet “urgent and
increasing needs”.205
2. Concrete policy options are available for States to effectively
address climate change
116. There is no shortage of concrete guidance for States committed to scaling-up their
mitigation efforts;206 nor is there any ambiguity about the scale of what needs to be done
to effectively combat the crisis.
117. The IPCC’s Sixth Assessment Report includes thousands of pages of analysis of
existing and available mitigation measures, including an assessment of their costeffectiveness
relative to their potential to achieve, in combination, the Paris temperature
201 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 7. See also, UNFCCC
COP, “Draft decision -/CMA.5: Outcome of the first global stocktake” (2023) (available here), para. 24.
202 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 33.
203 UNFCCC COP, Decision 2/CP.15, “Copenhagen Accord”, UN Doc. No. FCCC/CP/2009/11/Add.1,
18 December 2009 (available here) (hereinafter “UNFCCC COP, Decision 2/CP.15, “Copenhagen Accord”
(2009)”), pp. 5-7, para. 8 (“In the context of meaningful mitigation actions and transparency on
implementation, developed countries commit to a goal of mobilizing jointly USD 100 billion dollars a year by
2020 to address the needs of developing countries”).
204 UNFCCC COP, “COP26 Report: Addendum”, UN Doc. FCCC/CP/2021/12/Add.1, 8 March 2022 (available
here), pp. 5 and 12; see also, UNFCCC COP, “COP27 Report on Climate Finance”, UN Doc.
FCCC/CP/2022/10/Add.2, 17 March 2023 (available here), p. 2.
205 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), p. 7.
206 For further discussion of this principle, see, sub-section III.A.2, below.
44
goal. It is clear that all modelled pathways holding temperature increase to 1.5°C
require transitioning from unabated fossil fuels to very low or zero-carbon energy
sources; and, deploying carbon dioxide removal207 methods to counterbalance residual
emissions.208
118. The IPCC’s work also makes clear that, to this end, “several mitigation options” are
“technically viable”, “increasingly cost effective” and “generally supported by the
public”. Indeed, in some regions and sectors, “maintaining emissions-intensive
systems may […] be more expensive than transitioning to low emission systems”.209
There are, therefore, “many opportunities for implementing more ambitious mitigation
measures in all sectors and systems”;210 and, “more effective international cooperation
and credible initiatives can contribute to bridging emissions and implementation
gaps.”211
119. The COP Global Stocktake Decision similarly finds that “feasible, effective and lowcost
mitigation options are already available in all sectors to keep 1.5°C within reach
in this critical decade with the necessary cooperation on technologies and support”.212
Notably, the IPCC has identified mitigation options costing less than USD 100 per
tonne of CO2 which could reduce global GHG emissions by at least half of the 2019
level by 2030.213 Around 50 percent of that reduction could be achieved by mitigation
options costing less than USD 20 per tonne.214
207 “Carbon Dioxide Removal” refers to “technologies, practices, and approaches that remove and durably store
carbon dioxide (CO2) from the atmosphere.” Possible removal methods include soil carbon sequestration,
enhanced rock weathering, peat and wetland restoration and ocean fertilisation. See, IPCC, Sixth Assessment
Report, CDR Factsheet (available here).
208 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Summary for
Policymakers (available here), p. 24.
209 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), para. A.4.2.
210 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), para. 102.
211 UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), para. 22.
212 UNFCCC COP, “Draft Decision -/CMA.5: Outcome of the first global stocktake” (2023) (available here),
para. 16(c).
213 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Technical
Summary (available here), p. 108.
214 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Technical
Summary (available here), p. 108.
45
120. More specifically, the IPCC provides sector-by-sector accounting of where, precisely,
cost-effective emissions reductions can be found, including granular assessments of
energy systems,215 agriculture, forestry and other land uses (“AFOLU”),216 urban
systems and other settlements,217 buildings,218 transport,219 and industry.220 For
illustrative purposes, these are summarised in the table below.
215 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), pp. 613-746.
216 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), pp. 747-860.
217 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), pp. 861-952.
218 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), pp. 953-1048.
219 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), pp. 1049-1160.
220 IPCC, Sixth Assessment Report, 2022, Mitigation of Climate Change (Working Group III), Full Report
(available here), pp. 1161-1244.
46
Figure 9: “Many options available now in all sectors are estimated to offer substantial
potential to reduce net emissions by 2030” (Source: IPCC)
47
III. QUESTION (A): RELEVANT OBLIGATIONS AND THEIR CONTENT
121. The consequences of climate change touch on virtually every aspect of life on Earth. It
is not surprising, therefore, that the range of norms of international law engaged by the
climate crisis is as broad as the crisis itself. This is recognised in the request to the
Court, which identifies, illustratively and non-exhaustively, a great variety of rules of
international law ranging from those in human rights treaties, instruments agreed under
the international climate change regime and the law of the sea, to customary
international law.
122. In this Section, Antigua and Barbuda identifies and summarises the key international
law rules and principles that regulate States’ conduct in the face of climate change.
123. Sub-section A addresses: (1) the customary international law obligation of prevention;
(2) the principle of “Common but Differentiated Responsibilities and Respective
Capabilities” (“CBDR-RC”), including in light of different national circumstances;221
(3) the relevant rules and principles contained in the climate change regime (UNFCCC
and Paris Agreement): (4) human rights; (5) the United Nations Convention on the Law
of the Sea (“UNCLOS”); (6) the Convention on Biological Diversity (“CBD”); and
(7) international trade law.
124. Sub-section B applies these various rules and principles, to identify what States are
obliged to do under international law to ensure the protection of the climate system and
other parts of the environment from anthropogenic GHG emissions. In this regard,
Antigua and Barbuda also emphasises the obligations set out in sub-section B are
primary obligations; they do not, therefore, address responsibilities arising as regards a
breach of those obligations (including resulting loss and damage already suffered by
States including Antigua and Barbuda); such responsibilities are instead addressed in
Section 0 of this Written Statement.
221 For ease of reference, the term “CBDR-RC” is used throughout this Written Statement; this reference includes
the full term “common but differentiated responsibilities and respective capabilities in the light of different
national circumstances”.
48
A. Key international rules and principles
1. The obligation of prevention
125. The obligation of prevention is the cornerstone of international environmental law. It
originates in the customary international law principle of “no harm”, first formulated in
the Trail Smelter Arbitration (1941) in the form of a duty of diligence not to cause harm
to the territory of other States.222 It was later extended in both the 1972 Stockholm
Declaration on the Human Environment (Principle 21),223 and in the 1992 Rio
Declaration on Environment and Development (Principle 2) to encompass harm to areas
beyond national jurisdiction. The latter provides as follows:
States have, in accordance with the Charter of the United Nations
and the principles of international law, the sovereign right to
exploit their own resources pursuant to their own environmental
and development policies, and the responsibility to ensure that
activities within their jurisdiction or control do not cause damage
to the environment of other States or of areas beyond the limits
of national jurisdiction.224
126. The Court has repeatedly recognised the existence of the customary obligation of
prevention on States “to ensure that activities within their jurisdiction and control
respect the environment of other States or of areas beyond national control”.225
127. The importance of prevention in the context of environmental law arises from the reality
that environmental harm is often irreversible and, therefore, cannot be cured through
222 Trail smelter case (United States, Canada), Awards of 16 April 1938 and 11 March 1941, United Nations,
Reports of International Arbitral Awards (“RIAA”), Vol. III, pp. 1905-1982 (hereinafter “Trail Smelter”);
Corfu Channel (United Kingdom v. Albania), Merits, Judgment, I.C.J. Reports 1949 (hereinafter “Corfu
Channel”).
223 UN Conference on the Human Environment, Declaration on the Human Environment, U.N. Doc.
A/CONF.48/14/Rev.1, 16 June 1972 (hereinafter “Stockholm Declaration”).
224 UN Conference on Environment and Development, Rio Declaration on Environment and Development, U.N.
Doc. A/CONF.151/26/Rev.1 Vol. I, Annex I, 12 August 1992, (hereinafter “Rio Declaration”).
225 Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, I.C.J. Reports 1996 (I) (hereinafter
“Nuclear Weapons Advisory Opinion”), pp. 241-242, para. 29. See also, Gabčikovo-Nagymaros Project
(Hungary v. Slovakia), Judgment, I.C.J. Reports 1997 (hereinafter “Gabčikovo-Nagymaros”), pp. 77-78,
para. 140; Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment, I.C.J. Reports 2010
(hereinafter “Pulp Mills”), pp. 55-56, paras. 101-102; pp. 75-77, paras. 181-189; pp. 82-83, para. 204; Certain
Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua), I.C.J. Reports 2015 (II)
(hereinafter “Certain Activities (Merits)”), p. 706, para. 104; pp. 711-712, para. 118.
49
financial compensation.226 Absent cure, prevention is the only real option, and hence
the primary goal of many environmental obligations.
128. As noted above, the obligation of prevention has customary status.227 In addition, it has
been codified in a number of treaties. Importantly, the customary and the conventional
obligation of prevention shed light on one another: on the one hand, conventional
obligations expressing the obligation of prevention may elaborate on the content of the
customary obligation of prevention. On the other hand, the customary obligation of
prevention is relevant in the interpretation of conventional obligations expressing the
obligation of prevention.228
a. When is the prevention obligation triggered?
129. The prevention obligation applies when (1) an activity within a State’s jurisdiction is
(2) causing, or risks causing, significant harm that is (3) transboundary in nature.
Antigua and Barbuda unpacks these conditions in turn.
130. First, the prevention obligation applies to any activity planned or carried out in the
territory of a State, or otherwise under its jurisdiction or control.229
131. Second, the prevention obligation applies only in the case of significant harm, or risk
thereof.230 The significant harm could occur to the environment, persons, and/or
226 In Gabčíkovo-Nagymaros, p. 78, para. 140, the ICJ noted that it was “mindful that, in the field of environmental
protection, vigilance and prevention are required on account of the often irreversible character of damage to
the environment and of the limitations inherent in the very mechanism of reparation of this type of damage”.
227 Nuclear Weapons Advisory Opinion, pp. 241-242, para. 29. See also, Arbitration regarding the Iron Rhine
(‘Ijzeren Rijn’) Railway (Belgium v. Netherlands), Award of 24 May 2005, PCA Award Series (2007), RIAA
Vol. XXVII (hereinafter “Iron Rhine”), p. 116, paras. 222-223. See also, ILC, “Draft Articles on Prevention
of Transboundary Harm from Hazardous Activities, with commentaries”, ILC Yearbook 2001, vol. II, Part
Two (“hereinafter, “ILC, Draft Articles on Prevention of Harm from Transboundary Activities”),
commentary, para. 3.
228 See, the Vienna Convention on the Law of Treaties, 23 May 1969, 1155 U.N.T.S. 331, entered into force
27 January 1980 (hereinafter “Vienna Convention” or “VCLT”), Article 31(3)(c); see also, South China Sea
Arbitration (Philippines v. China), Award, PCA Case No 2013-19, ICGJ 495 (PCA 2016), 12 July 2016
(hereinafter “South China Sea Arbitration”), para. 941; Inter-American Commission on Human Rights, The
Environment and Human Rights (State Obligations in Relation to the Environment in the Context of the
Protection and Guarantee of the Rights to Life and to Personal Integrity – Interpretation and Scope of Articles
4(1) and 5(1) of the American Convention on Human Rights), Advisory Opinion OC-23/17, IACHR Series A
No 23, 15 November 2017 (hereinafter “IACHR Advisory Opinion”), paras. 131-133.
229 The activity should also not be prohibited by international law. See, ILC, Draft Articles on Prevention of
Transboundary Harm from Hazardous Activities, commentary to Article 1.
230 Pulp Mills, pp. 55-56, para. 101. See also, Convention on the Law of the Non-Navigational Uses of
International Watercourses, 21 May 1997, 2999 U.N.T.S. 77, entered into force 17 August 2014, Article 7(1);
50
property.231 Harm is considered “significant” if it is “more than ‘detectable’”, and need
not rise to “the level of ‘serious’ or ‘substantial’”.232 The significance of the harm must
be assessed on a case-by-case basis, taking account, in particular, of developments in
scientific knowledge and understanding.
132. The prevention principle applies not only when significant harm has occurred, but
whenever there is a risk thereof. There is, however, no need for scientific certainty that
the risk will occur; the obligation also “applies in situations where scientific evidence
concerning the scope and potential negative impact of the activity in question is
insufficient but where there are plausible indications of potential risks”.233
133. Third, to trigger the prevention obligation, the significant harm must be transboundary
in nature.234 This means that the harm must occur in the territory of another State,
irrespective of whether the affected State shares a border with the State where the
activity takes place; or in areas outside the jurisdiction of any State, such as the global
commons.235
b. What does the prevention obligation require?
i. Substantive element
134. The obligation of prevention has a positive and proactive character, requiring a duty of
due diligence to prevent harm to the environment (i.e., in the territory of another State
ILC, Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, commentary to
Article 2(a).
231 ILC, Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, Article 2(b).
232 ILC, Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, commentary to
Article 2, para. 4.
233 See, Responsibilities and obligations of States with respect to activities in the Area, Advisory Opinion,
1 February 2011, ITLOS Reports 2011 (hereinafter “Responsibilities in the Area”), p. 10, para. 57.
234 See, ILC, Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, commentary to
Article 2, para. 9.
235 These include, for instance, the high seas, international air space or the Antarctic. See, United Nations
Convention on the Law of the Sea, 10 December 1982, 1833 U.N.T.S 3, entered into force 16 November 1994
(hereinafter “UNCLOS”), Article 116-118 and 192; see also, Air Transport Association of America and others
v. Secretary of State for Energy and Climate Change (Case C-366/10) [2011] ECJ I-13755; Protocol on
Environmental Protection to the Antarctic Treaty, 4 October 1991, 2941 U.N.T.S. 3, entered into force
14 January 1998, Article 2.
51
or in areas beyond national jurisdiction).236 In the 2010 Pulp Mills decision, the ICJ
described the positive action required from States to respect the obligation of
prevention:
A State is … obliged to use all the means at its disposal in order
to avoid activities which take place in its territory, or in any area
under its jurisdiction, causing significant damage to the
environment of another State.237
135. A State must, thus, “use all the means at its disposal” to prevent transboundary harm
(or, put differently, must “deploy adequate means, exercise best possible efforts, … do
the utmost”).238 If, and only if, a State does its “utmost” – “using all the means at its
disposal” – to prevent transboundary harm (including fulfilment of the relevant
procedural obligations), does the State fulfil its duty to prevent significant harm.239
136. The level of diligence required from a State varies depending on the risk(s) involved;
and the means at the State’s disposal. Indeed, the standard of “due diligence” is a
“variable concept”,240 altering with: the degree of risk; the evolution in our
understanding of the risk and how to tackle it; and the means to address the risk at the
disposal of a given State.
137. First, the level of due diligence varies with the degree of risk: a higher standard of care
applies to activities involving higher risks, as compared to activities with lower risks.
The standard of care must be “appropriate and proportional to the degree of risk of
transboundary harm in the particular instance”.241
236 The original formulation in Trail Smelter was, at p. 1965: “[N]o State has the right to use or permit the use of
its territory in such a manner as to cause injury… to the territory of another or the properties or persons
therein…”.
237 See, Pulp Mills, pp. 55-56, para. 101 (emphasis added). The Seabed Disputes Chamber of ITLOS described
the duty of due diligence as requiring States “to deploy adequate means, to exercise best possible efforts, to
do the utmost” (see, Responsibilities in the Area, p. 43, para. 117); see also, Request for an Advisory Opinion
submitted by the Sub-Regional Fisheries Commission, Advisory Opinion, 2 April 2015, ITLOS Reports 2015
(hereinafter “IUU Advisory Opinion”), p. 41, para. 131; Indus Waters Kishenganga Arbitration (Pakistan v.
India), Partial Award, 18 February 2013, PCA Award Series (2014), para. 451, citing to Iron Rhine, para. 59;
and South China Sea Arbitration, para. 941.
238 See, IUU Advisory Opinion, p. 40, para. 129, citing to Responsibilities in the Area, p. 41, para. 110.
239 See, e.g., South China Sea Arbitration, paras. 941 and 977.
240 See, Responsibilities in the Area, p. 43, para. 117.
241 ILC, Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, commentary to
Article 3, para. 11 (emphasis added).
52
138. Second, and relatedly, the level of diligence varies over time, in light of new knowledge
about the level of risk and how to tackle it. That is, “measures considered sufficiently
diligent at a certain moment may become not diligent enough in light, for instance, of
new scientific or technological knowledge”.242 If new scientific or technological
knowledge shows that the risk is, or may be, higher than previously considered, a higher
standard of diligence will be required.
139. It follows that the prevention obligation is of a “continuing character”,243 requiring
States to review the adequacy of their level of diligence in light of new scientific or
technological knowledge. Only when States do so, are they able to adapt their level of
diligence in light of the evolving understanding on the level of risk.
140. Third, and finally, the level of diligence also varies depending on the “means at [the]
disposal” of each State.244 This means that, for a given risk, the standard of care required
from developed States – with greater means at their disposal – is higher than that
required for other States.
ii. Procedural element
141. There exists a further procedural component of the customary international law
obligation of prevention, specifically the obligation to cooperate, particularly through
notification and consultation with potentially affected States.245 States must comply
with the obligation at an early stage and in good faith.246
242 Responsibilities in the Area, p. 43, para. 117. See also, ILC, Draft Articles on Prevention of Transboundary
Harm from Hazardous Activities, commentary to Article 3, para. 11.
243 ILC, Draft Articles on Prevention of Transboundary Harm from Hazardous Activities, commentary to
Article 3, para. 5.
244 See, Pulp Mills, pp. 55-56, para. 101.
245 For a formulation of this obligation, see Principle 19 of the Rio Declaration: “States shall provide prior and
timely notification and relevant information to potentially affected States on activities that may have a
significant adverse transboundary environmental effect and shall consult with those States at an early stage
and in good faith.”
246 See, Corfu Channel, p. 22; see also, North Sea Continental Shelf (Federal Republic of Germany/Denmark;
Federal Republic of Germany/Netherlands), Judgment, I.C.J. Reports 1969 (hereinafter “North Sea
Continental Shelf”), pp. 46-47, para. 85; Nuclear Tests (Australia v. France), Judgment, I.C.J. Reports 1974,
p. 268, para. 46; Nuclear Tests (New Zealand v. France), Judgment, I.C.J. Reports 1974, p. 473, para. 49; Pulp
Mills, p. 67, paras. 145-146; MOX Plant (Ireland v. United Kingdom), Provisional Measures, Order of
3 December 2001, ITLOS Reports 2001 (hereinafter “MOX Plant”), p. 110, para. 82; Delimitation of the
Maritime Boundary in the Atlantic Ocean (Ghana v. Côte d’Ivoire), Provisional Measures, Order of 25 April
2015, ITLOS Reports 2015 (hereinafter “Delimitation of the Maritime Boundary”), pp. 160-161, para. 73;
IUU Advisory Opinion, p. 43, para. 140.
53
142. This obligation to cooperate has been construed in different ways by different
international courts and tribunals. At its most basic, cooperation requires, in all events,
notification of, and consultation with, potentially affected States.247 It can also include
exchange of information248 and/or joint evaluation of the environmental impact of
certain activities.249
2. The principle of common but differentiated responsibilities and
respective capabilities in light of different national circumstances
143. The principle of common but differentiated responsibilities and respective
capabilities250 has its origin in the general principle of equity.251
144. The concepts behind CBDR-RC were first expressed in the Stockholm Declaration,
which recognises the need to “tak[e] into account the circumstances and particular
requirements of developing countries”;252 and that “the applicability of standards which
are valid for the most advanced countries … may be inappropriate and of unwarranted
social cost for the developing countries”.253
145. The first formal expression of CBDR-RC is found in Principle 7 of the Rio Declaration
on Environment and Development:
States shall cooperate in a spirit of global partnership to
conserve, protect and restore the health and integrity of the
Earth’s ecosystems. In view of the different contributions to
global environmental degradation, States have common but
differentiated responsibilities. The developed countries
acknowledge the responsibility they bear in the international
pursuit of sustainable development in view of the pressures their
societies play on the global environment.
146. CBDR-RC, therefore, entails two interconnected dimensions. First, CBDR-RC stands
for universal solidarity, recognising the common responsibility of all States, both
247 See, Rio Declaration, Principle 19; see also, Certain Activities (Merits), pp. 707-708, para. 106; South China
Sea Arbitration, paras. 946, and 984-985.
248 See, MOX Plant, p. 111, para. 89(a).
249 See, Pulp Mills, para. 281; see also, MOX Plant, p. 111, para. 89(b).
250 See, footnote 221, above.
251 Equity is recognised as a general principle of international law under Article 38.1(c) of the ICJ Statute.
252 See, Stockholm Declaration, Principle 12.
253 See, Stockholm Declaration, Principle 23.
54
developing and developed, to address environmental degradation. Second, CBDR-RC
recognises that States have different responsibilities, in light of different levels of
(i) historical responsibility for environmental degradation; (ii) development; and
(iii) capacities to take effective action.
147. Consequently, CBDR-RC acknowledges equity and fairness in identifying who should
bear the burden of addressing environmental degradation; as well as calling for
effective action to be taken by States with the capacity – financial and technical – to
bear the burden.
148. CBDR-RC has found its way into virtually every multilateral environmental agreement,
and in particular features strongly throughout the international climate change
regime.254 The consistent recognition of the principle of CBDR-RC has been crucial in
securing the support of developing countries for the conclusion and implementation of
such multilateral agreements.
149. Over time, the principle has developed further nuance and flexibility, including through
recognition that the principle is also applied “in the light of different national
circumstances”.255 This means that, under the principle, developing countries are not
treated as an undifferentiated group. Instead, the principle recognises that there are
differences between and among developing countries themselves, both in terms of their
contribution to environmental degradation and their capacity to address that
degradation.
150. Initially, in the climate change regime, the UNFCCC and the Kyoto Protocol (1997)
treated “developing countries” as a single group, which was not subject to legally
binding obligations vis-à-vis emissions reduction targets.256 The Paris Agreement
254 See, e.g., United Nations Framework Convention on Climate Change, 9 May 1992, 1771 U.N.T.S. 107, entered
into force 21 March 1994 (hereinafter “UNFCCC”), Article 3.1 (among others); Convention on Biological
Diversity, 5 June 1992, 1760 U.N.T.S. 79, entered into force 29 December 1993 (hereinafter “Convention on
Biological Diversity”), Articles 8(m), 9(e), 12 and 20; Montreal Protocol on Substances that Deplete the
Ozone Layer, 16 September 1987, 1522 U.N.T.S. 3, entered into force 1 January 1989, Article 5 (among
others).
255 Paris Agreement to the United Nations Framework Convention on Climate Change, 12 December 2015,
U.N.T.S. 79, entered into force 4 November 2016 (hereinafter “Paris Agreement”), third preambular
paragraph.
256 The Kyoto Protocol to UNFCCC only established binding emission limitations for the “developed” country
Parties listed in Annex I; see also, Report of an International Legal Expert Group, “Principles of International
Law Relevant for Consideration in the Design and Implementation of Trade-Related Climate Measures and
55
(2015), by contrast, places obligations on all Parties, with the extent of the common
obligations differentiated on the basis of respective capabilities, in light of national
circumstances. The greater burden of emissions reductions, therefore, falls on
developed States, with the burden on developing States differentiated according to
circumstance. The Paris Agreement also acknowledges the special needs and
circumstances of least developed countries (“LDCs”) and SIDS. The importance of the
principle of CBDR-RC in the international climate change regime is addressed in
further detail below.
3. Climate change regime
a. UNFCCC
151. Agreed in 1992, the UNFCCC provides the legal “framework” for the international
climate change regime. The Convention begins with a provision that establishes an
overarching objective for the international climate regime as a whole:
The ultimate objective of this Convention and any related
legal instruments that the Conference of the Parties may adopt
is to achieve, in accordance with the relevant provisions of the
Convention, stabilization of greenhouse gas concentrations in
the atmosphere at a level that would prevent dangerous
anthropogenic interference with the climate system. Such a
level should be achieved within a time-frame sufficient to allow
ecosystems to adapt naturally to climate change, to ensure that
food production is not threatened, and to enable economic
development to proceed in a sustainable manner.257
152. Thus, from the outset, the regime picks up a core principle from customary international
law, namely: the need to prevent significant (“dangerous”) environmental harm
(interference with the climate system) resulting from anthropogenic GHG emissions.
It also calls for the objective to be achieved in a manner that enables the sustainable
economic development which is critical to the developing world.
153. Next, the UNFCCC sets out core “Principles”, which the Parties “shall be guided []
by”, not only in their actions “to implement its provisions” but also in “their actions to
Policies”, 2023, Forum on Trade, Environment, & the SDGs (TESS) (hereafter “TESS Expert Report,
Principles of International Law Relevant for Consideration in the Design and Implementation of Trade-
Related Climate Measures and Policies, September 2023”) (available here), p. 31.
257 UNFCCC, Article 2 (emphasis added).
56
achieve the objective of the Convention”.258 These echo the key features identified in
the UNFCCC’s objective.
154. First, the Principles reflect the need for measures to prevent “dangerous”
environmental harm.
155. Specifically, Principle 1 provides that the Parties “should protect the climate system
for the benefit of present and future generations of humankind”; and, Principle 3
provides that the Parties “should take precautionary measures to anticipate, prevent or
minimise the causes of climate change and mitigate its adverse effects.” It further
addresses the need for a precautionary approach, providing that “where there are threats
of serious or irreversible damage, lack of full scientific certainty should not be used as
a reason for postponing such measures”.
156. Second, the Principles reflect the need for a differentiated approach based on the
principle of CBDR-RC and the need for sustainable development.
157. Specifically, Principle 1 expressly incorporates the principle of CBDR-RC into the
principles of the international climate change regime, providing that the climate system
should be protected “on the basis of equity and in accordance with their common but
differentiated responsibilities and respective capabilities”. In the same vein, it provides
that “the developed country Parties should take the lead”.259 Principle 2 adds that “full
consideration” should be given to “the specific needs and special circumstances of
developing country Parties, especially those that are particularly vulnerable to the
adverse effects of climate change”.260
158. Principle 4 expressly recognises, among the principles of the climate change regime,
“the right” to “sustainable development”. Again acknowledging the need for
differentiation, it provides that “[p]olicies and measures to protect the climate system
against human-induced change should be appropriate for the specific conditions of each
258 UNFCCC, Article 3 (emphasis added).
259 UNFCCC, Article 3.1.
260 UNFCCC, Article 3.2.
57
Party”, “taking into account that economic development is essential for adopting
measures to address climate change”.261
159. Finally, Principle 5 calls on Parties to “cooperate to promote a supportive and open
international economic system that would lead to sustainable economic growth and
development in all Parties, particularly developing country Parties, thus enabling them
better to address the problems of climate change”.262
160. In this regard, Principles 4 and 5 establish a link between the objective of preventing
dangerous harm to the climate system, on the one hand, and the principles of CBDRRC
and sustainable development, on the other. Principles 4 and 5 recognise that, to
address their GHG emissions effectively (and thereby contribute to the prevention of
harm), it is “essential” for developing countries to progress along the pathway of
economic development. In other words, the Convention recognises that the capacity to
tackle climate change is inherently linked to development. This, in turn, requires
differentiation in favour of developing countries, through the principle of CBDR-RC
(Principle 1), accounting for the specific needs and special circumstances of developing
countries (Principle 2), with developed countries “to take the lead in combatting climate
change” (Principle 1).
161. Finally, the UNFCCC provides a basic set of commitments. All parties must develop
national inventories of GHG emissions;263 must formulate policies and measures to
limit GHG emissions;264 and submit communications containing information relating
to their national inventories, and steps taken or envisaged to implement the
Convention.265
162. Developed countries (as defined in Annex I) must adopt policies and measures to limit
GHG emissions “with the aim of returning individually or jointly” to their 1990 levels
by “the end of the present decade”, i.e., the year 2000.266 A sub-set of Annex I
261 UNFCCC, Article 3.4.
262 UNFCCC, Article 3.5.
263 UNFCCC, Article 4.1(a).
264 UNFCCC, Article 4.1(b).
265 UNFCCC, Article 12.1.
266 UNFCCC, Article 4.2(a) and (b).
58
developed countries, that is the Organisation for Economic Co-operation and
Development countries, have additional commitments to provide “new and additional
financial resources to meet the agreed full costs incurred by developing country Parties”
in complying with their reporting requirements; and “to meet the full incremental costs”
of their emissions reduction measures.267 A subset of developed countries (as defined
in Annex II) commit to assisting particularly vulnerable developing countries in
“meeting costs of adaptation” to the adverse effects of climate change.
b. Paris Agreement
163. In 2015, the Paris Agreement was adopted “in pursuit of the objective of the
Convention” and is “guided by its principles”.268 The Paris Agreement “enhances the
implementation of the Convention, including its objective”.269 The Paris Agreement
thus provides a series of specific commitments that pursue the overall objective of
preventing dangerous anthropogenic interference with the climate system in a way
that enables economic development to proceed in a sustainable manner.
164. To this end, Article 2.1 of the Paris Agreement identifies three high level goals through
which the Parties “aim[] to strengthen the global response to the threat of climate
change”, consistent with the objective of the UNFCCC.270 These goals are:
• a temperature goal: “hold[] the increase in the global average temperature to well
below 2°C and pursue efforts to limit the temperature increase to 1.5°C”, in
recognition that this would “significantly reduce the risks and impacts of climate
change”271 (“Paris temperature goal”);
• an adaptation goal: “[enhancing] the ability to adapt to the adverse impacts of
climate change and foster climate resilience”;272
• a financing goal: “making finance flows consistent with a pathway towards low
greenhouse gas emissions and climate-resilient development”.273
267 UNFCCC, Article 4.3. and 4.4.
268 See, Paris Agreement, preamble; see also, Article 2.1 which provides “[t]his Agreement, in enhancing the
implementation of the Convention, including its objective, aims to …”. (emphasis added).
269 Paris Agreement, Article 2.1.
270 Paris Agreement, Article 2.1.
271 Paris Agreement, Article 2.1(a).
272 Paris Agreement, Article 2.1(b); see also, Article 7.1, “the global adaptation goal”.
273 Paris Agreement, Article 2.1(c).
59
165. Like the UNFCCC, Article 2.2 of the Paris Agreement expressly sets forth that the
Agreement “will be implemented to reflect equity and the principle of common but
differentiated responsibilities and respective capabilities, in the light of different
national circumstances”. As explained above, this provision adds considerable nuance
to the principle of CBDR-RC, through the words “in the light of different national
circumstances”.
166. Much of the remainder of the Paris Agreement sets out provisions operationalising how
the Agreement’s goals are to be achieved. In general terms, these provisions address
three distinct aspects of the response to climate change: actions to mitigate global
warming (climate change mitigation); actions to adapt to the effects of climate change
(climate change adaptation); and loss and damage resulting from climate change.
167. First, with respect to mitigation, Article 4 sets out requirements related to NDCs,
which are the “contribution” that each State makes to achieving the Paris temperature
goal by reducing emissions, as one aspect of preventing dangerous anthropogenic
interference with the climate system.
168. Second, Article 7 elaborates on the need for adaptation measures, providing, among
other things, that “[e]ach Party shall, as appropriate, engage in adaptation planning
processes and the implementation of actions” and “should, as appropriate, submit and
update periodically an adaptation communication”.274
169. Third, as regards support for developing countries, Article 9 provides that developed
country States “shall provide financial resources to assist developing country Parties
with respect to both mitigation and adaptation”. In addition, Articles 10 and 11
provide for alternative forms of assistance from developed to developing States, in
particular technology transfer and capacity building.
170. Finally, Article 8 “recognizes the importance of averting, minimizing and addressing
loss and damage associated with the adverse of effects of climate change”.275 That is,
274 Paris Agreement, Article 7.9 and 7.10 (emphasis added).
275 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
paras. 121-135.
60
the harms of climate change that have already occurred and will occur, which cannot
be addressed through adaptation measures.
4. International human rights law
171. The term “human rights” refers to a catalogue of legal rights, developed through
international texts, inherent to all human beings – regardless of their nationality, place
of residence, sex, national or ethnic origin, colour, religion, language, or any other
status. These rights are interrelated, interdependent and indivisible. With regard to all
human rights, States have three obligations.
172. These obligations are: (1) a “negative” obligation to respect human rights, namely to
refrain from interfering with the enjoyment of human rights; (2) a “positive” obligation
to protect human rights, which requires action to safeguard individuals, and groups of
individuals, against possible human rights abuses from third parties; and (3) a further
“positive” obligation to fulfil human rights, namely to take positive action to facilitate
the enjoyment of human rights.
173. Below, Antigua and Barbuda addresses first how these obligations are expressed in
various binding legal instruments; second the (non-binding) recognition of the right to
a clean, healthy and sustainable environment by the UN General Assembly; and third
how climate change has impacted human rights.
a. International texts on human rights
174. In human rights law, the key text is the Universal Declaration of Human Rights
(“UDHR”), adopted by the UN General Assembly in 1948.276 It is the first legal
instrument aimed at the universal protection of fundamental human rights, and it is the
cornerstone of modern human rights law. Its 30 articles provide the principles and
foundations of present and future conventions, treaties and other legal instruments
relating to human rights.
175. Since 1948, a number of treaties and intergovernmental declarations have
supplemented the UN’s proclamation of human rights. In particular, the UDHR was
complemented in 1966 by the International Covenant on Civil and Political Rights
276 UN General Assembly, Resolution 217 A III: Universal Declaration of Human Rights, A/RES/3/217,
10 December 1948 (“Universal Declaration of Human Rights”).
61
(“ICCPR”) and the International Covenant on Economic, Social and Cultural Rights
(“ICESCR”).277 Each of these Covenants has been ratified by 167 States and they both
entered into force in 1976.
176. In addition to the UDHR and the two Covenants, the UN system is the source of many
other international human rights instruments. They include, for instance:
• the International Convention on the Elimination of All Forms of Racial
Discrimination;278
• the Convention on the Elimination of All Forms of Discrimination Against Women;279
• the Convention on the Rights of the Child;280
• the International Convention on the Protection of the Rights of all Migrant Workers and
their Families;281
• the International Convention on the Rights of Persons with Disabilities.282
177. Several regional human rights instruments have also been adopted over the last 70
years. While regional in membership, these treaties are broad in scope, because they
are not confined to the protection of specific human rights or specific categories of
rightsholders. The interpretation and application of these instruments by relevant
regional bodies (while legally binding only in the regional context) can help to inform
the content of the equivalent rights as expressed in the UN instruments.
277 UN General Assembly, International Covenant on Civil and Political Rights, 16 December 1966, 999
U.N.T.S. 171, entered into force 23 March 1976 (hereinafter “ICCPR”); UN General Assembly, International
Covenant on Economic, Social and Cultural Rights, 16 December 1966, 993 U.N.T.S. 3, entered into force
3 January 1976 (hereinafter “ICESCR”).
278 UN General Assembly, International Convention on the Elimination of All Forms of Racial Discrimination,
21 December 1965, 660 U.N.T.S. 195, entered into force 4 January 1969 (hereinafter “ICERD”).
279 UN General Assembly, Convention on the Elimination of All Forms of Discrimination against Women,
18 December 1979, 1249 U.N.T.S. 13, entered into force 3 September 1981 (hereinafter “CEDAW”).
280 UN General Assembly, Convention on the Rights of the Child, 20 November 1989, 1577 U.N.T.S 3, entered
into force 2 September 1990 (hereinafter “CRC”).
281 UN General Assembly, International Convention on the Protection of the Rights of All Migrant Workers and
Their Families, 18 December 1990, 2220 U.N.T.S. 3, entered into force 1 July 2003 (hereinafter “ICRMW”).
282 UN General Assembly, Convention on the Rights of Persons with Disabilities, 8 February 2007, 2515
U.N.T.S. 3, entered into force 3 May 2008 (hereinafter “CRPD”).
62
178. The formulation and development of human rights is not limited to binding
international treaties – whether of universal or regional character. In fact, a series of
soft law instruments complete the framework of human rights law relating to climate
change. Such soft law instruments include in specific declarations adopted by States;
and resolutions of the UN General Assembly and other UN bodies, including UN
human rights bodies – such as the Human Rights Council, and the Office of the High
Commissioner for Human Rights. This includes, most notably, the UN General
Assembly’s recognition of the right to a clean, healthy and sustainable environment
(addressed below).
179. Treaty bodies have also adopted a wide range of instruments that have further
developed the content of human rights and the corresponding State obligations. Notable
examples are the general comments and recommendations adopted by the Committee
on Economic, Social and Cultural Rights, the Committee on the Rights of the Child,
the Committee on the Elimination of Discrimination against Women, and, more
broadly, by the Human Rights Committee.
b. The right to a clean, healthy and sustainable environment for
present and future generations
180. The right to a clean, healthy and sustainable environment has been recognised as a
universal human right by the Human Rights Council and by the UN General
Assembly.283
181. Specifically, in October 2021, the Human Rights Council, in its Resolution 48/13,
recognised “the right to a clean, healthy and sustainable environment as a human right
that is important for the enjoyment of human rights”, and encouraged States “to adopt
283 UN Human Rights Council, Resolution 48/13: The Human Right to a Clean, Healthy and Sustainable
Environment, UN Doc. A/HRC/RES/48/13, 18 October 2021 (hereinafter “UN Human Rights Council,
Resolution 48/13: The Human Right to a Clean, Healthy and Sustainable Environment, 2021”); UN
General Assembly, Resolution 76/300: The Human Right to a Clean, Healthy and Sustainable Environment,
A/RES/76/300, 28 July 2022 (hereinafter “UN General Assembly, Resolution 76:300: The Human Right to
a Clean, Healthy and Sustainable Environment, 2022”). The origins of the right to a clean, healthy and
sustainable environment date back to Principle 1 of the Stockholm Declaration. The right is also included in
several regional human rights instruments drafted after the 1970s, such as the African Charter on Human and
Peoples’ Rights, 27 June 1981, 1520 U.N.T.S. 217, entered into force 21 October 1986 (hereafter “ACHPR”).
See also, Organization of American States (“OAS”), American Convention on Human Rights, 22 November
1969, 1144 U.N.T.S. 123, entered into force 18 July 1978; Additional Protocol to the American Convention
on Human Rights in the Area of Economic, Social and Cultural Rights, 16 November 1999, A-52 (hereinafter
“Protocol of San Salvador”), Article 11(1); Arab Charter on Human Rights, Article 38; ASEAN Human
Rights Declaration, 18 November 2012, para. 28(f).
63
policies for the enjoyment of the right to a clean, healthy and sustainable
environment”.284 This was followed by the adoption of a Resolution of the UN General
Assembly in July 2022.285
182. The recognition of the right at the universal level acknowledges the inherent
interdependence of environmental protection and enjoyment of human rights – a
healthy environment is fundamental to the full enjoyment of a vast range of human
rights and, conversely, environmental degradation interferes with the enjoyment of
these rights. Over the past 45 years, the meaning, content, and scope of the human right
to a healthy environment – as well as its relationship with other human rights – have
been progressively refined and clarified by national tribunals and regional human rights
courts.286 There is now no doubt that the right to a healthy environment is an
autonomous right, which “differs from the environmental content that arises from the
protection of other rights”.287
183. In the 2001 Ogoni case, the African Commission on Human and Peoples’ Rights
considered the content of the right, finding that (as enshrined in Article 24 of the African
Charter on Human and Peoples’ Rights), it “requires the State to take reasonable and
other measures to prevent pollution and ecological degradation, to promote
conservation, and to secure an ecologically sustainable development and use of natural
resources”.288 In other words, to comply with the human rights in Article 24, States
need to comply with the environmental principle of prevention, which requires each
State to act with due diligence to avoid transboundary harm.289
184. In its 2017 Advisory Opinion, the Inter-American Court of Human Rights confirmed
that the right to a healthy environment (as enshrined in the Protocol of San Salvador)
284 UN Human Rights Council, Resolution 48/13: The Human Right to a Clean, Healthy and Sustainable
Environment, 2021.
285 UN General Assembly, Resolution 76:300: The Human Right to a Clean, Healthy and Sustainable
Environment, 2022.
286 See also, Framework Principles on Human Rights and the Environment, in “Report of the Special Rapporteur
on the Issue of Human Rights Obligations Relating to the Enjoyment of a Safe, Clean, Healthy and Sustainable
Environment”, UN Doc. A/HRC/37/59, 24 January 2018, Annex.
287 IACHR Advisory Opinion, para 63.
288 ACHPR, Communication 155/96: Social and Economic Rights Action Center (SERAC) and Center for
Economic and Social Rights (CESR) v. Nigeria (2001) (hereinafter “Ogoni”), para. 52.
289 Rio Declaration, Principle 2.
64
presents both individual and collective connotations and that, “[i]n its collective
dimension”, it “constitutes a universal value that is owed to both present and future
generations”.290
185. Climate change shares this clear and defining collective dimension. The environment
and the climate system are indeed a “common good”, which is a collective right and
which may benefit all humans. Moreover, climate change is an inherently
intergenerational problem,291 with extremely serious implications not only for the
present but for future generations as well. It follows that, in the context of climate
change, this collective right should be collective also in a temporal rather than merely
spatial dimension, as it can include the rights of future generations as well as those of
the present.292
c. Impact of climate change on human rights
186. The impact of climate change on human rights is vast and uncontested. In the words of
Mary Robinson, former UN High Commissioner for Human Rights, climate change is
“potentially the greatest threat to human rights in the twenty-first century”.293
187. In 2008, the Human Rights Council adopted Resolution 7/23 on Human rights and
Climate Change, which represented the first UN resolution to state explicitly that
climate change poses “an immediate and far-reaching threat to people and
communities around the world and has implications for the full enjoyment of human
290 IACHR Advisory Opinion, para. 59.
291 Edith Brown Weiss, “Climate Change, Intergenerational Equity, and International Law”, Vermont Journal of
Environmental Law 9 (2008), p. 615.
292 Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, Advisory Opinion,
I.C.J. Reports 2019, Separate Opinion of Judge Cançado Trindade, pp. 237-238, para. 261; Alan Boyle, ‘The
Role of International Human Rights Law in the Protection of the Environment’ in Alan Boyle and Michael
Anderson (eds.), Human Rights Approaches to Environmental Protection (Oxford University Press, 1996),
p. 46; Edith Brown Weiss, “Our Rights and Obligations to Future Generations for the Environment”, American
Journal of International Law 84 (1990), pp. 198 and 203.
293 See, Mary Robinson, “Why climate change is a threat to human rights”, TED Women, May 2015 (available
here).
65
rights”.294 Today, the fact that climate change strongly affects human rights is set forth
in a wide variety of UN procedures and instruments,295 as well as in legal scholarship.296
188. Similarly, the link between human rights and climate change is expressed in legal
instruments relating to climate change, such as the Cancún Agreements – the first to
call for Parties to “fully respect human rights” in all climate change related actions297 –
and the Paris Agreement.298 The Paris Agreement addresses human rights in its
preamble:
Acknowledging that climate change is a common concern of
humankind, Parties should, when taking action to address
climate change, respect, promote and consider their
respective obligations on human rights, the right to health,
the rights of indigenous peoples, local communities,
migrants, children, persons with disabilities and people in
vulnerable situations and the right to development, as well as
294 UN Human Rights Council, Resolution 7/23: Human Rights and Climate Change, UN Doc. A/HRC/RES/7/23,
28 March 2008. In the Resolution, the Human Right Council asked the Office of the United Nations High
Commissioner for Human Rights (OHCHR) to prepare a study on the implications of climate change for the
enjoyment of human rights; see, OHCHR, Report on the Relationship between Climate Change and Human
Rights, UN Doc. A/HRC/10/61, 15 January 2009 (hereinafter “OHCHR, Report on the Relationship between
Climate Change and Human Rights”).
295 See, e.g., Joint Statement of the Special Procedure Mandate Holders of the Human Rights Council on the UN
Climate Change Conference, 7 December 2009 (available here); UN General Assembly, Report of the
Independent Expert on the Issue of Human Rights Obligations Relating to the Enjoyment of a Safe, Clean,
Healthy and Sustainable Environment, John H. Knox: Mapping Report, UN Doc. A/HRC/25/53, 30 December
2013. See also, the following resolutions passed by the UN Human Rights Council: Resolution 18/22: Human
rights and climate change, UN Doc. A/HRC/RES/18/22, 17 October 2011; Resolution 26/27: Human rights
and climate change, UN Doc. A/HRC/RES/26/27, 15 July 2014; Resolution 28/11: Human rights and the
environment, UN Doc. A/HRC/RES/28/11, 7 April 2015; Resolution 29/15: Human rights and climate change,
UN Doc. A/HRC/RES/29/15, 22 July 2015; Resolution 32/33: Human rights and climate change, UN Doc.
A/HRC/RES/32/33, 18 July 2016; Resolution 35/20: Human rights and climate change, UN Doc.
A/HRC/RES/35/20, 7 July 2017; Resolution 38/4: Human rights and climate change, UN Doc.
A/HRC/RES/38/4, 16 July 2018; Resolution 41/21: Human rights and climate change, UN Doc.
A/HRC/RES/41/21, 12 July 2019; Resolution 44/7: Human rights and climate change, UN Doc.
A/HRC/RES/44/7, 23 July 2020; Resolution 47/24: Human rights and climate change, UN Doc.
A/HRC/RES/47/24, 26 July 2021; Resolution 50/9: Human rights and climate change, UN Doc.
A/HRC/RES/50/9, 14 July 2022. See also, United Nations Development Programme (“UNDP”), Human
Development Report 2007/2008 Fighting Climate Change: Human solidarity in a divided world; UNEP,
Climate Change and Human Rights, December 2015.
296 See, e.g., J.H. Knox, “Linking Human Rights and Climate Change at the United Nations”, Harvard
Environmental Law Review, 33(477), 2009, p. 477; and L. Rajamani, “Human Rights in the Climate Change
Regime” in J.H. Knox and R. Pejan (eds.), The Human Right to a Healthy Environment (Cambridge University
Press 2018), p. 236.
297 UNFCCC COP, Decision 1/CP.16, “The Cancun Agreements: Outcome of the work of the Ad Hoc Working
Group on Long-term Cooperative Action under the Convention”, UN Doc. FCCC/CP/2010/7/Add.1, 15 March
2011 (available here), para. 8.
298 Paris Agreement, third preambular paragraph.
66
gender equality, empowerment of women and
intergenerational equity [emphasis added].
189. Given the scope of its effects, climate change could, in principle, bear upon the
enjoyment of all human rights. At the same time, certain specific rights are most
directly and clearly implicated, according to the facts as established by the IPCC.299
These are set out below.
190. The right to life is explicitly protected under the ICCPR as well as several other
universal and regional human rights instruments.300 It has been described by the Human
Rights Committee as the “supreme right”, “basic to all human rights”, from which no
derogation is permitted even in case of public emergency.301 It has further held that
climate change is among “the most pressing and serious threats to the ability of present
and future generations to enjoy the right to life”.302 Observed and projected climate
change effects already pose direct and indirect threats to the right to life, and will
continue to do so.303 Among others, the latest IPCC Report stresses with high
confidence that climate change “will significantly increase ill health and premature
death from the near- to long-term”, and that increased heatwaves and droughts linked
to climate change will “lead to health risks of malnutrition and climate-related
mortality”, especially in developing countries and in tropical regions.304 Climate change
will also exacerbate the rate and intensity of extreme weather events, which are already
significantly impairing individuals’ enjoyment of their right to life,305 especially in
developing countries and in SIDS.
299 See, sub-sections II.C.2 and II.C.3, above.
300 ICCPR, Article 6; CRC, Article 6; UDHR, Article 3.
301 Human Rights Committee, General Comment No. 6, Article 6: Right to life, 30 April 1982, para. 1.
302 Human Rights Council, Views adopted by the Committee under article 5(4) of the Optional Protocol,
concerning communication No. 2728/2016, para. 9.4, citing to Human Rights Committee, General Comment
No. 36, Article 6: right to life, UN Doc. CCPR/C/GC/36, 3 September 2019, para. 62 (hereinafter “HRC,
General Comment No. 36”).
303 OHCHR, Report on the Relationship between Climate Change and Human Rights, paras. 21-24.
304 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report (available
here), pp. 63 and 95; see also, sub-section II.C.2, above.
305 HRC, General Comment No. 36, para. 26. See also, Inter-Agency Standing Committee (“IASC”), IASC
Operational Guidelines on Human Rights and Natural Disasters – Protecting Persons Affected by Natural
Disasters, Guiding Principles on Internal Displacement, UN Doc. E/CN.4/1998/53/Add.2, 11 February 1998,
p. 5, Annex.
67
191. The right to adequate food306 is linked to the “fundamental right of everyone to be
free from hunger”,307 which requires States to “take necessary action to mitigate and
alleviate hunger … even in times of natural or other disasters”.308 The IPCC has
emphasised the widespread impact of climate change on food security, in particular as
far as vulnerable communities are concerned.309
192. The right to water310 “entitles everyone to sufficient, safe, acceptable, physically
accessible and affordable water for personal and domestic uses”.311 With regard to the
right to water, States have a “constant and continuing” obligation to ensure,
expeditiously and effectively, the full realisation of the right to water,312 and to ensure
that there is sufficient safe water for both present and future generations.313 Climate
change, and in particular the loss of glaciers and the increase in frequency and intensity
of extreme weather events, have exposed millions of peoples to reduced water security,
especially in developing countries, SIDS, and among vulnerable communities.314
306 ICESCR, Article 11; CRC, Article 24(c); CRPD, Article 25(f) and Article 28(1); CEDAW, Article 14(2)(h);
ICERD, Article 5.
307 ICESCR, Article 11(2).
308 CESCR, General Comment No. 12, Article 11: Right to adequate food, UN Doc. E/C.12/1999/5, 12 May 1999,
para. 6.
309 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III) (available here), p. 16.
310 CESCR, General Comment No. 15, Articles 11 and 12: Right to water, UN Doc. E/C.12/2002/11, 20 January
2003 (hereinafter “General comment No. 15”). See, CEDAW, Article 14(2)(h); CRPD, Article 28(2)(a);
CRC, Article 24(2)(c).
311 CESCR, General Comment No. 15, para. 2.
312 CESCR, General Comment No. 15, para. 18.
313 CESCR, General Comment No. 15, para. 28. See also, United Nations Conference on Environment and
Development, Report of the United Nations Conference on Environment and Development - Agenda 21, UN
Doc. A/CONF.151/26/Rev.1 (Vol.1), p. 9, Chapters 5, 7 and 18; Report of the World Summit on Sustainable
Development, Annex: Plan of Implementation of the World Summit on Sustainable Development, UN Doc.
A/CONF.199/20*, 2002, paras. 7 (a), 7(l), 7(m), 36 and 38.
314 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report (available
here), p. 16; OHCHR, Report on the Relationship between Climate Change and Human Rights, para. 29. See
also, Human Rights Committee, Report of the United Nations High Commissioner for Human Rights on the
scope and content of human rights obligations related to equitable access to safe drinking water and sanitation
under international human rights instruments, UN Doc. A/HRC/6/3, 16 August 2007; United Nations
Economic and Social Council, Realization of the right to drinking water and sanitation, UN Doc.
E/CN.4/Sub.2/2005/25, 11 July 2005; see also, sub-section II.C.2, above.
68
193. The right to health315 refers to “the right of everyone to the enjoyment of the highest
attainable standard of physical and mental health”316 and it extends to the underlying
determinants of health, such as “food and nutrition, housing, access to safe and potable
water and adequate sanitation, safe and healthy working conditions, and a healthy
environment”.317 Climate change has already adversely affected human physical and
mental health in many different ways,318 especially in developing countries, including
SIDS, as well as with regard to the most vulnerable segments of the population (i.e.,
women, children, persons with disabilities).319
194. The right to adequate housing320 has been defined as “the right to live somewhere in
security, peace and dignity”.321 A number of observed and projected effects of climate
change are already, and will continue producing, significant adverse impacts on the
right to adequate housing. These include for instance, sea level rise and stronger and
more frequent hurricanes, in particular as far as SIDS and low-lying coastal States are
concerned, as well as flooding. In Antigua and Barbuda, the most serious threat to
housing is the increased frequency and strength of hurricanes. These effects will have
impacts on many coastal settlements and will lead to the relocation of peoples and
communities, as well as to internal displacement and international migration.
195. The right to self-determination322 has been defined in the ICCPR as the right to
determine freely one’s political status and freely pursue one’s economic, social and
315 ICESCR, Article 12; CEDAW, Articles 12 and 14(2)(b); ICERD, Articles 5(e)(iv); CRC, Article 24; CRPD,
Articles 16(4), 22(2), and 25; ICRMW, Articles 43(1)(e), 45(1)(c), and 70. See also ICESCR Articles 7(b) and
10.
316 ICESCR, Article 12(1).
317 CESCR, General Comment 14, Article 12: The right to the highest attainable standard of health, UN Doc.
E/C.12/2000/4, 11 August 2000, para. 4.
318 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II), Technical
Summary (available here), p. 50.
319 Committee on the Rights of the Child, General Comment No. 4, Adolescent Health and Development in the
Context of the Convention on the Rights of the Child, UN Doc. CRC/GC/2003/4, 1 July 2003; Committee on
the Elimination of Discrimination against Women, General recommendation 24, Article 12 of the Convention
on the Elimination of All Forms of Discrimination against Women – women and health, UN Doc. A/54/38,
4 May 1999, (Part I) Chapter I.
320 ICESCR, Article 11. See also, UDHR, Article 25(1); ICERD, Article 5 (e)(iii); CEDAW, Article 14(2); CRC,
Article 27, para. 3; ICRMW, Article 43(1)(d); CRPD, Articles 9(1)(a), 28(1) and 28(2)(d).
321 CESCR, General Comment No. 4, The Right to Adequate Housing (Art. 11(1) of the Covenant), contained in
UN Doc. E/1992/23, reprinted in UN Doc. HRI/GEN/1/Rev. 6, p.18, 12 May 2003, para. 7.
322 The right to self-determination is enshrined in Articles 1 and 55 of the Charter of the United Nations (1945);
see also, United Nations General Assembly, Resolution 41/128: Declaration on the Right to Development,
69
cultural development.323 Sea level rise, coastal erosion and inundation are threatening
the habitability and, in the longer term, the territorial existence of a number of SIDS
and low-lying island States.324 Changes in the climate are also threatening to deprive
indigenous populations of their traditional territories and sources of livelihood. Both
impacts have clear implications for the right to self-determination.325
196. The right to a clean, healthy and sustainable environment has been incorporated in
a number of regional human rights treaties, more than a hundred national constitutions
and has been recognised as a human right by the HRC and the UN General Assembly.326
A number of observed and projected effects of climate change are already, and will
continue producing, significant adverse impacts on the right to a clean, healthy and
sustainable environment, whose substantive components include, “clean air, a safe
[and stable] climate, access to safe water and adequate sanitation, healthy and
sustainably produced food [as well as] healthy biodiversity and ecosystems”.327
197. Moreover, climate change is susceptible of producing effects that are and will be felt
most acutely by those segments of the population that are already in vulnerable
situations due to factors such as poverty, gender, age, minority status, and disability.328
These include, for instance, women, children, persons with disabilities, and indigenous
peoples.
5. United Nations Convention on the Law of the Sea
198. The UNCLOS establishes “a legal order for the seas and oceans which will facilitate …
the equitable and efficient utilization of their resources, the conservation of their living
4 December 1986, Article 1, para. 2; United Nations General Assembly, Resolution 61/295: United Nations
Declaration on the Rights of Indigenous Peoples, UN Doc. A/RES/61/295, 13 September 2007, Articles 3 and
4.
323 ICCPR, Article 1.
324 OHCHR, Report on the Relationship between Climate Change and Human Rights, para. 40.
325 OHCHR, Report on the Relationship between Climate Change and Human Rights, para. 40.
326 See, sub-section III.B.3, above.
327 Human Rights Committee, Report of the Special Rapporteur on the issue of human rights obligations relating
to the enjoyment of a safe, clean, healthy and sustainable environment, UN Doc. A/HRC/43/53, 30 December
2019, para. 2.
328 See, e.g., IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II),
Full Report (available here), p. 145.
70
resources and the … protection and preservation of the marine environment”.329
Currently, there are 169 Parties to UNCLOS.
199. Part XII of the UNCLOS, “Protection and Preservation of the Marine Environment”, is
of particular relevance to the question before the Court.
200. Part XII opens with Article 192, titled “General Obligation”. It reads: “States have the
obligation to protect and preserve the marine environment”. The ordinary meaning of
the term “protect” is to “defend or guard from danger or injury”, “keep safe, take care
of”.330 The ordinary meaning of the term “preserve” is “to keep from perishing”,
“prevent”, or “make lasting”.331 Together, the verbs in Article 192 – “protect” and
“preserve” – require States Parties to safeguard the marine environment against future
harm, and to maintain and improve its present condition.332
201. The “general obligation” in Article 192 is further elaborated in other, more detailed,
provisions of Part XII. Among those is Article 194, which concerns the protection and
preservation of the marine environment against one particular threat, “pollution of the
marine environment”.
202. The expression “pollution of the marine environment” is defined in Article 1(4) of the
UNCLOS. Under that definition “pollution of the marine environment” is defined as:
(1) “the introduction by man, directly or indirectly, of substances or energy into the
marine environment”; and (2) when that results, or is likely to result, in “deleterious
effects” for the marine environment.
203. When there is “pollution of the marine environment”, Article 194 sets out obligations
for the States Parties in following terms:
States shall take, individually or jointly as appropriate, all
measures consistent with this Convention that are necessary to
prevent, reduce and control pollution of the marine environment
from any source, using for this purpose the best practicable
means at their disposal and in accordance with their capabilities,
329 See, UNCLOS, fourth preambular paragraph.
330 Oxford English Dictionary, “protect, n.” (available here).
331 Oxford English Dictionary, “preserve, n.” (available here).
332 See, South China Sea Arbitration, para. 941.
71
and they shall endeavour to harmonize their policies in this
connection.333
204. This provision requires States Parties to identify the measures that are necessary to
prevent, reduce, and control pollution of the marine environment; and – using the best
practical means available in accordance with their capabilities – adopt these measures.
205. The terms prevent, reduce and control are cumulative, and each term has a distinct
meaning which must be given effect. First, the term “prevent” means “[t]o preclude the
occurrence of (an anticipated event, state, etc.); to render (an intended, possible, or
likely action or event) impractical or impossible by anticipatory action; to put a stop
to”.334 Second, the ordinary meaning of “reduce” is “[t]o bring down or diminish to …
a smaller number, amount, quantity, extent, etc. … ”.335 Third, “control” means “[t]o
restrain from action, hold in check; (in later use) esp. to curb the growth or spread of”;
and “regulating and directing”; “management”.336
206. There are circumstances that may engage all three verbs, such as where pollution has
already occurred and is still accumulating in the marine environment. In such
circumstances, taking the necessary measures to merely “control” marine pollution
would not be sufficient to discharge the obligation in Article 194.
207. Article 194 establishes a due diligence obligation. In practice, this requires States to
employ “all the means at their disposal”, “in accordance with their capabilities”, to
prevent, reduce and control pollution to the marine environment.337 Put differently,
States must “deploy adequate means, exercise best possible efforts, [] do the utmost”.338
208. Finally, this language introduces differentiation between and among Parties to
UNCLOS in the performance of their obligations, with a view to addressing the
333 UNCLOS, Article 194(1).
334 Oxford English Dictionary, “prevent, v.” (available here); see also, M.H. Nordquist (ed.), United Nations
Convention on the Law of the Sea, A Commentary, (Dordrecht, Martinus Nijhoff, 1985), para. 194.10(b).
335 Oxford English Dictionary, “reduce, v.” (available here).
336 Oxford English Dictionary, “control, v.” (available here).
337 Alleged Violations of Sovereign Rights and Maritime Spaces in the Caribbean Sea (Nicaragua v. Colombia),
Preliminary Objections, Judgment, I.C.J. Reports 2016 (I), p. 43, para. 95.
338 IUU Advisory Opinion, p. 40, para. 129, citing to Responsibilities in the Area, p. 41, para. 110.
72
concerns of some developing States that mandatory measures to protect the marine
environment could compromise their development.339
6. Convention on Biological Diversity
209. The Convention on Biological Diversity, adopted in 1992 during the Rio Earth Summit,
is the first international treaty comprehensively addressing biodiversity. The CBD arose
from the growing recognition of the international community that biodiversity is “a
global asset of tremendous value to present and future generations” and “the threat to
species and ecosystems has never been so great as it is today”.340
210. The objectives of the CBD are the “conservation of biological diversity, the sustainable
use of its components and the fair and equitable sharing of the benefits arising out of
the utilization of genetic resources … and by appropriate transfer of relevant
technologies … ”.341
211. Article 3 recognises, as a principle, that States have “the responsibility to ensure that
activities within their jurisdiction or control do not cause damage to the environment of
other States or of areas beyond the limits of national jurisdiction”.
212. Article 6 of the CBD requires Contracting Parties to “[d]evelop national strategies,
plans and programmes for the conservation and sustainable use of biological diversity”
and “[i]ntegrate, as far as possible and as appropriate, the conservation and sustainable
use of biological diversity into relevant sectoral or cross-sectoral plans, programmes
and policies”.342 These two prongs of the general obligation of Article 6 function as a
“chronological series of steps” for States to develop a blueprint which “at minimum”
reflect how the obligations of the CBD will be implemented.343
339 The language was included in the Convention by the Kenyan draft articles, but its origin can be found in
Principle 7 of the Stockholm Declaration. See, M.H. Nordquist (ed.), United Nations Convention on the Law
of the Sea, A Commentary (Dordrecht, Martinus Nijhoff, 1985), para. 194.10(b).
340 Convention on Biological Diversity, Introduction.
341 Convention on Biological Diversity, Article 1; see also, Article 2, defining “biodiversity” as “the variability
among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems
and the ecological complexes of which they are part; this includes diversity within species, between species
and of ecosystems”.
342 Convention on Biological Diversity, Articles 6(a) and 6(b) (emphasis added).
343 See, L. Glowka, F. Burhenne-Guilmin, H. Synge, JA. McNeely, L. Gündling, A Guide to the Convention on
Biological Diversity (IUCN Environmental Law Centre 1994) (available here), p. 29.
73
213. Building on Article 6, the remainder of the CBD requires Contracting Parties to take
specific action in view of the objectives of the CBD. For instance, States shall “promote
the protection of ecosystems, natural habitats and the maintenance of viable populations
of species in natural surroundings” and “adopt measures for the recovery and
rehabilitation of threatened species”.344
214. The CBD also gives expression to the principle of CBDR-RC. Its key obligations are
qualified by the terms “in accordance with its particular conditions and capabilities”.345
The Principles further recognise that “economic and social development and poverty
eradication are the first and overriding priorities of developing countries”.346
7. International trade law
215. The measures adopted by States in response to climate change may implicate areas of
international law relating to the environment; and they may also implicate international
law related to trade, mostly notably under the World Trade Organization’s (“WTO”)
“covered agreements”.347 This will be the case where, for example, States’ emissions
reduction measures include border charges and restrictions, internal taxes, regulations,
production standards and subsidies. Such measures are legal hybrids, for which it is
appropriate to take account of all relevant parts of international law. To this end,
Antigua and Barbuda sets out certain key rules and principles of international trade law.
216. The first preambular recital to the WTO Agreement provides as follows:
Recognizing that relations in the field of trade and economic
endeavor should be conducted with a view to raising standards
of living, ensuring full employment and a large and steadily
growing volume of real income and effective demand, and
expanding the production of and trade in goods and services,
while allowing for the optimal use of the world’s resources in
accordance with the objective of sustainable development,
seeking both to protect and preserve the environment and to
enhance the means for doing so in a manner consistent with
344 Convention on Biological Diversity, Article 8(d) and Article 9(c).
345 Convention on Biological Diversity, Article 6.
346 Convention on Biological Diversity, nineteenth preambular paragraph.
347 The WTO “covered agreements” are those listed in the Marrakesh Agreement Establishing the World Trade
Organization, 15 April 1994, 1867 U.N.T.S. 3, 1868 U.N.T.S. 3, 1869 U.N.T.S. 3, entered into force 1 January
1995, Article 2.2 and 2.3.
74
their respective needs and concerns at different levels of
economic development [emphasis added].
217. WTO adjudicators have found that the preamble thus contains a “specific
acknowledgment [] about the importance of coordinating policies on trade and the
environment”,348 and indicates that the drafters of the Agreement were “fully aware of
the importance and legitimacy of environmental protection as a goal of national and
international policy”.349
218. To this end, the preamble “explicitly acknowledges” the objective of “sustainable
development”.350 The preamble, thereby, explicitly acknowledges that the protection of
the environment happens “in a manner consistent with [WTO Members’] respective
needs and concerns at different levels of economic development”. This preambular
language gives “colour, texture and shading” to the interpretation of the General
Agreement on Tariffs and Trade 1994 (“GATT 1994”) (and other WTO covered
agreements).351
219. Article 3.2 of the WTO’s Dispute Settlement Understanding (“DSU”) directs WTO
adjudicators to interpret the provisions of the WTO agreements “in accordance with the
customary rules of interpretation of public international law”, including, specifically,
Article 31 of the Vienna Convention. It is well-accepted in WTO law that the direction
in Article 3.2 of the DSU “reflects a measure of recognition” that WTO law “is not to
be read in clinical isolation from public international law”.352
220. This position is consistent with the presumption in international law that different parts
of international law should, as far as possible, be interpreted and applied in a coherent
and consistent manner.353 In the words of the International Law Commission (“ILC”),
“[i]t is a generally accepted principle that when several norms bear on a single issue
they should, to the extent possible, be interpreted so as to give rise to a single set of
348 Appellate Body Report, US – Gasoline, p. 30.
349 Appellate Body Report, US – Shrimp, paras. 129-131.
350 Appellate Body Report, US – Shrimp, paras. 129-131.
351 Appellate Body Report, US – Shrimp, paras. 129-131.
352 Appellate Body Report, US – Gasoline, p. 17.
353 See, TESS Expert Report, Principles of International Law Relevant for Consideration in the Design and
Implementation of Trade-Related Climate Measures and Policies, September 2023 (available here), p. 8.
75
compatible obligations.”354 This principle of systemic integration avoids fragmentation,
and gives full effect to all relevant aspects of international law, in a coherent and
effective manner.
221. In considering the relevance of international trade law to climate-related measures, two
categories of provisions under the GATT 1994 bear particular emphasis: those setting
out obligations on WTO Members; and those setting out possible defences to a violation
of those obligations. Antigua and Barbuda briefly describes each in turn.
222. There are two key sets of “cornerstone” obligations in the GATT 1994 which promote
the liberalization of international trade. The first relates to market access, i.e., the
ability of imported goods to cross the border, and access the market, of an importing
country.355 Market access can be impeded through the imposition of tariffs (i.e.,
broadly, charges imposed on or in connection with importation) or quantitative
restrictions (limits on the volume of goods that may be imported or exported into or
from a Member’s territory). Under Article II of the GATT 1994, WTO Members may
not impose tariffs on imported goods which are in excess of a negotiated maximum
level.356 Further, under Article XI of the GATT 1994, quantitative restrictions – which
include outright bans – are prohibited altogether.
223. The second cornerstone set of obligations in the GATT 1994 relates to nondiscrimination.
Under the “most favored nation” principle set out in Article I, WTO
Members may not discriminate between “like” products originating from different
exporting countries. Under the “national treatment” principle set out in Article III,
WTO Members may not discriminate between domestic products, on the one hand, and
354 Report of the Study Group of the International Law Commission, “Fragmentation of International Law:
Difficulties Arising from the Diversification and Expansion of International Law”, UN Doc. A/CN.4/L.702,
18 July 2006 (available here) (hereinafter “ILC, Report on Fragmentation of International Law”), p. 8.
Referring to this ILC Report, the WTO Appellate Body also explained that “Article 31(3)(c) of the Vienna
Convention is considered an expression of the ‘principle of systemic integration’ which, in the words of the
ILC, seeks to ensure that ‘international obligations are interpreted by reference to their normative environment’
in a manner that gives ‘coherence and meaningfulness’ to the process of legal interpretation” (Appellate Body
Report, EC and Certain member States – Large Civil Aircraft, para. 845); See also, Panel Report, Indonesia –
Autos, para. 14.28 (“in public international law there is a presumption against conflict”), and footnote 649
(with references to the literature).
355 See, Katherine Connolly and Nicolas Lockhart, “An Introduction to Core Principles of International Trade
Law” in Daniel Bethlehem et al. (eds) The Oxford Handbook of International Trade Law (OUP, 2023).
356 The negotiated maximum level is referred to as a “tariff binding”; each tariff binding is product-specific, and
is recorded in each Member’s “Schedule of Concessions”.
76
any “like” imported products, on the other hand, either in their fiscal treatment of the
relevant products (Article III:2) or their regulatory treatment (Article III:4).
224. Under the GATT 1994, the policy objective behind a measure is not, as a general rule,
taken into account when assessing whether the measure violates one of these
obligations. For example, WTO adjudicators have consistently rejected arguments that
a difference in treatment stemming from a “legitimate regulatory distinction” must be
considered under the non-discrimination obligations.357
225. Instead, such considerations are assessed under the provisions providing possible
defenses to a violation of the GATT 1994. Of particular note is Article XX (general
exceptions), consisting of ten paragraphs and a chapeau.
(a) The paragraphs set out a closed list of justifiable measures, corresponding to
specific policy objectives. WTO adjudicators have adopted a two-step approach
under Article XX: First, is the measure provisionally justified under one of the
subparagraphs? Second, does the measure satisfy the conditions in the
chapeau?358 The responding Member bears the burden of proof under each
step.359
(b) The chapeau provides that measures cannot be justified if they constitute
“arbitrary or unjustified discrimination” or “a disguised restriction on
international trade”.
226. As regards trade-related climate measures, two paragraphs are especially relevant: (b),
covering measures “necessary for the protection of human, animal or plant life or
health”; and (g) measures “relating to the conservation of exhaustible natural
resources”. To successfully rely on a subparagraph, the responding Member must show
the measure indeed pursues the identified objective; and that the measure has the
requisite connection to that objective (i.e., “necessary for”, or “related to”).
227. Under the chapeau, the adjudicator will typically broaden the analysis, looking at how
the measure is applied in practice; this assessment can take into account a broad range
357 See, e.g., Appellate Body Report, EC – Seal Products, para. 5.117.
358 Appellate Body Report, US – Gasoline, p. 22; and Appellate Body Report, Brazil – Retreaded Tyres, para. 139.
359 Appellate Body Reports, US – Gasoline, p. 22; US – Wool Shirts and Blouses, p. 16; Indonesia — Import
Licensing Regimes, para. 5.42.
77
of factors, including provisions from binding or non-binding international legal
instruments, beyond international trade.360
B. What are the obligations of States under international law to ensure the
protection of the climate system and other parts of the environment from
anthropogenic GHG emissions?
1. Obligations related to mitigation
228. States are under an obligation to do their utmost, using all the means at their disposal
to achieve rapid, deep and sustained GHG emission reductions sufficient to prevent
significant environmental harm, in a manner consistent with the principle of fairness,
equity and CBDR-RC.
229. This obligation arises independently under several sources of law, and in each instance
the obligation arising under one source of law support those arising under the other
sources. The key sources of this mitigation obligation are addressed in turn.
230. Antigua and Barbuda begins with the international climate change regime, which
comprises the UNFCCC and the Paris Agreement (sub-section (a)). Other sources of
international law impose parallel and complementary obligations on States to prevent
significant environmental harm resulting from GHG emissions, in a manner consistent
with the principle of fairness, equity and CBDR-RC. In this respect, Antigua and
Barbuda examines the customary obligation of prevention (sub-section (b)), followed
by human rights law (sub-section (c)); and the law of the sea (sub-section (d)).
Finally, international trade law imposes obligations on States adopting mitigation
measures affecting international trade (sub-section (e)). Antigua and Barbuda refers to
other rules and principles of international law where relevant under each section.
360 In US - Shrimp, for example, the Appellate Body took into account provisions of treaties, and several soft law
instruments of international environmental law, including Principle 12 of the Rio Declaration and Agenda 21.
Appellate Body Report, US - Shrimp, paras 168 and 169. See also, Appellate Body Report, US - Shrimp (Art.
21.5), para. 124. In EC - Seals, in interpreting Article 2.1 of the TBT Agreement (where some of the analysis
was considered to apply to Article XX of the GATT as well), the panel referred to other international law
instruments such as the UN Declaration on the Rights of Indigenous Peoples, the UN General Assembly
Resolution 61/295 (2007), ILO Convention 169, and the Charter of the Inuit Circumpolar Council.
78
a. Obligations arising under the international climate change
regime
231. The UNFCCC establishes the framework for the international climate change regime.
The objective of the UNFCCC, and of “any related legal instruments that the
Conference of the Parties may adopt”, is to stabilise GHG emissions in the atmosphere
at a level that prevents dangerous anthropogenic interference with the climate
system.361 To contribute to that objective, Article 2.1(a) of the Paris Agreement
establishes a temperature goal for climate change mitigation. That goal calls for
mitigation action to hold global warming well below 2.0°C, and to pursue efforts to
limit the increase in atmospheric warming to 1.5°C, recognising that the latter
temperature “would significantly reduce the risks and impacts of climate change”
(“Paris temperature goal”).362
232. Article 4 is the main provision of the Paris Agreement establishing mitigation-related
obligations. The key subparagraphs are Article 4.2 and Article 4.3:
2. Each Party shall prepare, communicate and maintain
successive nationally determined contributions that it intends to
achieve. Parties shall pursue domestic mitigation measures, with
the aim of achieving the objectives of such contributions.
3. Each Party’s successive nationally determined contribution
will represent a progression beyond the Party’s then current
nationally determined contribution and reflect its highest
possible ambition, reflecting its common but differentiated
responsibilities and respective capabilities, in the light of
different national circumstances.
233. These terms establish a mandatory obligation to “prepare, communicate and maintain
successive nationally determined contributions”.363 States are in violation of Article 4
if they do not do so.
234. Below, the Written Statement addresses the term “nationally determined contribution”
in Article 4.2, before turning to each of the three key verbs in Article 4.2.
361 UNFCCC, Article 2.
362 Paris Agreement, Article 2.1(a).
363 Paris Agreement, Article 4.2 (emphasis added).
79
i. “Nationally determined contribution”
235. The term “nationally determined contribution” appears first in Article 3 of the Paris
Agreement, which provides:
As nationally determined contributions to the global response
to climate change, all Parties are to undertake and communicate
ambitious efforts as defined in Articles 4, 7, 9, 10, 11 and 13 with
the view to achieving the purpose of this Agreement as set out in
Article 2.
236. The ordinary meaning of the word “contribution” means the “action of … giving as
one’s part to a common fund or stock; the action of lending aid or agency to bring
about a result.”364
237. The term “contribution” in Article 4.2, read in light of Articles 2 and 3, refers to the
mitigation action of each State, in particular, its national share towards the achievement
of the collective “global response to climate change”.365 A COP Decision, Decision
4/CMA.1, clarifies that an NDC is expected to contribute, more specifically, to the Paris
temperature goal and, with separate mention, the broader UNFCCC objective of
preventing dangerous anthropogenic interference with the climate system.366
238. Article 4.1 sets forth a collective pathway for States to achieve the Paris temperature
goal. Under that pathway, Parties “aim to reach global peaking of greenhouse gas
emissions as soon as possible” and “to undertake rapid reductions thereafter in
accordance with best available science”.367 Article 4.1 also recognises that “peaking
will take longer for developing country Parties”, which is consistent with facilitating a
364 Oxford English Dictionary, “contribution, n.” (available here) (emphasis added).
365 Paris Agreement, Article 2.
366 See, UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21”, UN Doc. FCCC/PA/CMA/2018/3/Add.1, 15 December 2018 (available here) (hereinafter
“UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018)”), Annex I to the Decision, para. 7. This decision was adopted pursuant to Article 4.8 of the
Paris Agreement, which provides that in “communicating their nationally determined contributions, all Parties
shall provide the information necessary for clarity, transparency and understanding” of those NDCs.
367 Paris Agreement, Article 4.1 (emphasis added).
80
fair and just transition that allows developing countries to progress along the
development curve.368
239. In order to contribute to the collective pathway, Articles 4.2 and 4.3 of the Paris
Agreement impose obligations on States with respect to their respective national
pathways to reducing emissions. This national pathway is set forth through the NDC,
with “successive” NDCs due every five years.369 For each successive NDC, Article 4.2
establishes three distinct and cumulative obligations: States are under an obligation to
(i) “prepare” (ii) “communicate”; and, (iii) “maintain” their successive NDCs.
240. States are constrained in how they perform each of these three obligations, pursuant to
the terms of Article 4, read in context with the relevant COP Decision and in light of
the object and purpose of the Paris Agreement.
ii. States shall prepare a nationally determined
contribution
241. Under Article 4.2 of the Paris Agreement, States must “prepare” an NDC “that it intends
to achieve”. The ordinary meaning of the verb “prepare” is to make ready for some
purpose.370 The relevant purpose of the NDC is identified in Article 3 (quoted above)
as being “to achiev[e] the purpose of this Agreement”. In this context, “prepare” in
Article 4.2 means that States must make ready an NDC that is fit for the purposes of
contributing to the collective efforts to meet the Paris temperature goal and to prevent
dangerous anthropogenic interference within the climate system.
242. As the text of Article 4.2 provides, the NDC reflects the contribution that the State
“intends to achieve”. The use of the verb “intend” shows that an NDC is forwardlooking,
setting out the State’s emissions reduction target. This is confirmed by COP
Decision 4/CMA.1, which refers to an NDC as establishing a “target” for emissions
reductions.371
368 The Paris Agreement recognises that States are at varying stages in the development curve; see, Paris
Agreement, third preambular paragraph, Articles 2.2 and 4.3; UNFCCC, sixth preambular paragraph,
Articles 3.1 and 4.1.
369 Paris Agreement, Articles 4.2, 4.9, 4.10.
370 Oxford English Dictionary, “prepare, v.” (available here).
371 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision, paras. 1(b), 1(d), 2(b), and 3(a).
81
243. The Paris Agreement leaves States with a degree of discretion as to how they “prepare”
their NDC and, in particular, what level of emission reductions they set as target, and
how they will achieve that target. At the same time, Article 4, read together with COP
Decision 4/CMA.1,372 places limits on that discretion.
244. Antigua and Barbuda address two aspects of these limits in turn. The first set of limits
concerns temporal and other scoping dimensions of an NDC, while the second concerns
the level of the NDC.
(1) Scoping of an NDC
245. To “prepare” an NDC, States must necessarily consider certain factors that determine
the scope of an NDC. The consideration of these factors is, by definition, inherent in
the task of preparing an emissions reduction target. The scoping factors include: the
baseline or starting-point for the target; the period over which the target will be
achieved; the type of emissions included; the type of emission-generating activities
included; and the methodologies used for making the necessary assessments (e.g., GHG
measurement).
246. The need for States to assess these scoping factors in preparing an NDC is confirmed
expressly by COP Decision 4/CMA.1. This COP Decision is focused on the elements
of an NDC that must be “communicate[d]” by a State, pursuant to Article 4.13 of the
Paris Agreement. These requirements are addressed again below under the
“communication” limb of Article 4.2.
247. COP Decision 4/CMA.1 calls for an explanation of the following elements that bear
upon the scope of an NDC: (a) the reference (i.e., starting) point for calculating
emission reductions; (b) time frames for implementation; (c) scope and coverage,
including sectors, gases, categories and pools covered by the NDC; and (d) assumptions
and methodological approaches used for accounting for GHG emissions and
372 COP Decisions can be considered subsequent agreements under Article 31.3(a) of the VCLT. The ICJ has
clarified that resolutions like COP decisions have interpretive relevance “when they are adopted by consensus
or by a unanimous vote” (see, Whaling in the Antarctic (Australia v. Japan: New Zealand intervening),
Judgment, I.C.J. Reports 2014 (hereinafter “Whaling in the Antarctic”), p. 248, para. 46). Equally, the ILC
has explained that the “legal effect of a decision adopted within the framework of a Conference of States
Parties ... may embody, explicitly or implicitly, a subsequent agreement under article 31, paragraph 3 (a)”
(see, ILC, “Draft conclusions on subsequent agreements and subsequent practice in relation to the
interpretation of treaties”, 2018, UN Doc. A/73/10, Conclusion 11.2 and see commentary para. 35 thereto as
regards Article 31.3 and other subsequent practice for the purpose of Article 32).
82
removals.373 To be able to communicate these elements, a State must give proper
consideration to each of them in preparing its NDC.
(2) Level of the emissions reduction target in each successive NDC
248. The level of the emissions reduction target in each successive NDC is among the most
important features of an NDC. Again, although States enjoy some discretion in setting
the level of their NDC, limits are placed on that discretion.
249. Specifically, with respect to the level of the emissions reduction target, an NDC must:
(a) be prepared in light of best available scientific evidence; (b) reflect the “highest
possible ambition” and a “progression”; (c) reflect fairness, equity and CBDR-RC;
(d) reflect special dispensation for least developed States and SIDS; and (e) be informed
by the results of the Global Stocktake. Antigua and Barbuda addresses each factor in
turn.
(a) Consideration of the best available scientific evidence
250. The inherent nature of an NDC requires States to prepare an NDC, under Article 4.2,
using the best available scientific evidence. Article 4.1, which serves as immediate
context, confirms this point, with an express reference to “best available science”.
251. The purpose of an NDC is to hold global warming to levels that meet the Paris
temperature goal and that avert dangerous anthropogenic interference with the climate
system. It is impossible for a State to prepare an NDC fit for these purposes without
considering the relevant science. Indeed, science informs necessary judgments on
virtually every question relevant to the preparation of an NDC, including: expected
national and international emissions pathways, according to different emissions
reductions scenarios; expected temperature increases and harms under these different
scenarios; sources of GHG emissions; the quantum and impact of different GHGs;
technology for reducing emissions; and methodologies for making measurements. The
list goes on.
373 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision. This COP Decision is relevant to the interpretation
of Article 4.2 and 4.8 of the Paris Agreement (see, footnote 372, above).
83
252. With respect to the best available science, the work of the IPCC serves as a valuable
resource for States in making these assessments. Indeed, COP Decision 4/CMA.1
expressly mentions that the work of the IPCC is to be used in preparing an NDC.374
(b) The NDC must reflect the “highest possible ambition” and a
“progression”
253. In preparing an NDC, a State must decide on the extent of the target emissions
reductions and, hence, the extent of its “contribution”. The target encompasses the pace
of emissions reductions over time, because a more ambitious target for the NDC period
means a faster pace of reductions during that period.
254. Under Article 4.3 of the Paris Agreement, each successive NDC “will … reflect
[States’] highest possible ambition” at the time when the NDC is established; and each
successive NDC “will represent a progression” from the last, ratcheting up the
emissions reduction target from one NDC to the next.
255. The word “will” in Article 4.3 must be interpreted using the usual rules of treaty
interpretation.375 The ordinary meaning of the word, as used in the provision, is
straightforward, without any uncertainty or ambiguity. The word is an auxiliary verb,
which connotes a “command, promise, or determination”.376
256. Article 4.3 must also be understood in light of COP Decision 4/CMA.1. This Decision
requires a State to explain how it considers that an NDC represents: (1) the State’s
highest possible ambition at that time; and (2) a progression from the previous NDC.377
The need for a State to explain these two points shows that a State is bound to prepare
an NDC that demonstrably (in the communication) meets these requirements.
374 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision, paras. 3(b), 5(d), 5(e), and 5(f)(iii).
375 Specifically, the rules of treaty interpretation set out in Articles 31 and 32 of the VCLT.
376 Oxford English Dictionary, “will n.” (available here). The Cambridge Dictionary further defines the term as
a “determination to do something, despite any difficulties or opposition”. See, Cambridge Dictionary, “will
n.” (available here).
377 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex 1 to the Decision, para. 6. Specifically, para. 6 of Annex 1 to the
Decision requires States to explain how their NDC addresses Article 4.3 of the Paris Agreement (“Each Party’s
successive nationally determined contribution will represent a progression beyond the Party’s then current
nationally determined contribution and reflect its highest possible ambition…”) (emphasis added).
84
257. As a result, Article 4.3, read in context of the COP Decision 4/CMA.1, therefore
establishes an obligation on States to set the level of their NDC at its “highest possible
ambition”, with each successive NDC representing a “progression” on the last.378
258. In this regard, Antigua and Barbuda wishes to highlight that the meaning of the word
“highest” is also free from doubt. “Highest” is a superlative, here denoting the greatest
emissions reduction target that can be achieved (“possible”). The term “highest
ambition possible” must be shaped by the purpose of an NDC, which is to contribute to
the Paris temperature goal and prevent dangerous anthropogenic interference with the
climate system.
259. In that regard, there is a scientific consensus that significant harm is already occurring;
that, as between the 1.5°C and 2°C, harms for people and the environment are
significantly worse at the higher temperature and, indeed, that, with each increment of
warming, the harm is markedly worse.379 The Paris Agreement confirms explicitly that
1.5°C “would significantly reduce the risks an impacts of climate change”, as compared
with 2°C. Two further COP Decisions resolve to pursue efforts to the increase to
1.5°C.380 These decisions also explicitly recognise the scientific consensus, expressed
in the IPCC’s findings, that States must collectively make rapid, deep and sustained
reductions to their emissions.
260. The IPCC has found that, to hold global warming to 1.5°C with no or limited overshoot,
collective emissions must be reduced by 43 percent by 2030, by 60 percent by 2035, by
69 percent by 2040, by 84 percent by 2050, compared with 2019 level; reaching net
zero CO2 emissions by early 2050; and net zero GHG emissions by early 2070.381
261. As explained in paragraphs 41 to 47 above, to calculate these figures, the IPCC has
concluded that, to hold global warming to 1.5°C, cumulative total atmospheric
378 Paris Agreement, Article 4.3.
379 See, sub-sections II.C.2 and II.C.3, and para. 49.
380 UNFCCC COP, Decision 1/CMA.3, “Glasgow Climate Pact”, UN Doc. FCCC/PA/CMA/2021/10/Add. 1,
13 November 2021 (available here) (hereinafter “UNFCCC COP, Decision 1/CMA.3, “Glasgow Climate
Pact” (2021)”); UNFCCC COP, Decision 1/CMA.4, “Sharm el-Sheikh Implementation Plan”, UN Doc.
FCCC/PA/CMA/2022/10/Add.1, 20 November 2022 (available here).
381 UN, “New Analysis of National Climate Plans: Insufficient Progress Made, COP28 Must Set Stage for
Immediate Action”, 14 November 2023 (available here). See also, IPCC, Sixth Assessment Report, 2023,
Synthesis Report (Working Groups I, II and III), Full Report (available here), para. B.6.1, Table SPM.1, Figure
2.5 Panel b and Table 3.1.
85
emissions, subsequent to 2019, cannot exceed a defined quantity (500 GtCO2 from the
beginning of 2020). This is the RCB to hold global warming to 1.5°C (“1.5°C
RCB”).382 If cumulative emissions exceed this RCB, global warming will exceed the
temperature goal.
262. Recent research by the Global Carbon Project has concluded that the 1.5°C RCB is
significantly smaller than the IPCC reported in 2021.383 Specifically, the new data
shows that the 1.5°C RCB from the beginning of 2024 (275 GtCO) is almost half of the
1.5°C RCB, available from the beginning of 2020 (500 GtCO), as previously estimated
by the IPCC.384
263. At this stage, in 2024, humanity has already exploited a very considerable portion of
the 1.5°C RCB.385 In part, this is because past emissions reduction efforts, including
since 2019, have not been significant enough.
264. As a result, based on the most recent research, States are obliged to accelerate their
mitigation efforts in light of the small and, indeed, dwindling 1.5°C RCB. According
to the IPCC, to meet their obligations under Article 4.3, States must, collectively,
reduce emissions by the collective targets aligned with the IPCC 1.5°C pathway; that
is, by at least 43 percent by 2030, 60 percent by 2035, by 69 percent by 2040, and 84
percent by 2050, compared with 2019 levels; and to reach net zero CO2 emissions by
early 2050; and net zero GHG emissions by early 2070. Antigua and Barbuda recalls
that the IPCC’s work reflects an international scientific consensus. Antigua and
Barbuda also notes that States must take into account the most recent scientific
evidence, implying that, collectively, States must reduce their emissions by
considerably more than the collective targets aligned with the IPCC 1.5°C pathway.
382 See, sub-section II.B.4.
383 Pierre Friedlingstein et al., “Global Carbon Budget 2023” in Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5304.
384 See, sub-section II.B.4, above.
385 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 25.
86
265. In the section below, Antigua and Barbuda explains that the responsibility of each State
to contribute to the collective targets aligned with the IPCC 1.5°C pathway must be
based on the principle of fairness, equity and CBDR-RC.
266. In sum, without prejudice to whether States have already violated Article 4.3, they will
violate Article 4.3 if they do not now prepare an NDC that accelerates their mitigation
efforts through rapid, deep and sustained reductions to their emissions, reflecting their
“highest possible ambition” and, as Antigua and Barbuda explains next, the principle
of fairness, equity and CBDR-RC.
(c) The NDC must reflect fairness, equity and the principle of
CBDR-RC
267. Article 4.3 of the Paris Agreement explicitly states that an intended NDC will reflect a
State’s own “common but differentiated responsibilities”, its own “respective
capabilities” to tackle climate change, and its own “national circumstances”.
268. The context of Article 4.3 further confirms the importance of the principle of fairness,
equity and CBDR-RC in the international climate change regime. It is expressed in the
Principles in Article 3 of the UNFCCC and in Article 2.2 of the Paris Agreement.
Parties have, thereby, committed to respect the principle of fairness, equity and CBDRRC
in their actions to implement the Paris Agreement.
269. The principle of fairness, equity and CBDR-RC recognises the different respective
contributions made by developed and developing States to climate change, and their
different capacities to tackle climate change, in light of different levels of
development.386
270. Pursuant to Article 4.3, therefore, developed States must make a larger contribution to
tackling climate change than developing States, especially least developed and SIDS.
Several other paragraphs of Article 4 confirm this view:
• Article 4.1 recognises that “peaking will take longer for developing country
Parties”.
• Article 4.4 provides that “developed country Parties should continue taking the
lead by undertaking economy-wide absolute emissions reduction targets”,
386 See, sub-section III.A.2, above.
87
whereas developing countries are “encouraged to move over time towards
economy-wide emission reduction or limitation targets in the light of different
national circumstances”.
271. As a result, developed countries must “prepare” an NDC that includes a larger
emissions reduction target than those set by developing countries, including relative to
the size and scope of their respective economies.
272. This differentiation in the levels of the national contribution is consistent with the object
and purpose of the UNFCCC (incorporated into the Paris Agreement),387 which
provides that climate change mitigation action “should be achieved …. [t]o enable
economic development to proceed in a sustainable manner”. The Principles of the
UNFCCC also recognise that, to “contribute” effectively to global emissions
reductions, developing countries may need to progress their economic development.
273. COP Decision 4/CMA.1 underscores the importance of equity and the principle of
fairness, equity and CBDR-RC in the preparation of an NDC. In communicating an
NDC, a State “shall”388 include information on “[f]airness considerations, including
reflecting on equity”;389 and it must explain how its NDC “has addressed” the
differentiation between developed, developing countries, least developed and small
island developing States.390 The requirement for a State to explain these equity-related
points when communicating its NDC shows that a State is bound to prepare an NDC
that demonstrably reflects fairness, equity and CBDR-RC, which for developed States
will be a proportionately larger emissions reduction target than those set by developing
States.
387 See, Paris Agreement, third preambular paragraph and Article 2.
388 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), para. 7 (“Parties shall provide the information necessary for clarity,
transparency and understanding contained in Annex I as applicable to their nationally determined
contributions”).
389 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision, para. 6(b).
390 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), para. 6 and Annex I to the Decision. Specifically, Annex I requires each
Party to explain how it has addressed Article 4.3 (“[d]eveloped country parties should take the lead…”) and
Article 4.4 of the Paris Agreement (“[t]he least developed countries and small island developing States may
prepare and communicate strategies, plans and actions for low greenhouse gas emissions development
reflecting their special circumstances”).
88
274. The COP’s First Global Stocktake Decision, adopted on 13 December 2023,
underscores the need for mitigation action to be equitable, based on the principle of
fairness, equity and CBDR-RC, in order to ensure a just transition in the context of
sustainable development and poverty eradication.391 Specifically, emphasising “the
need for urgent action and support to keep the 1.5°C goal within reach”, States
“commit[ted] to accelerate action in this critical decade on the basis of the best available
science, reflecting equity and the principle of common but differentiated
responsibilities and respective capabilities in the light of different national
circumstances and in the context of sustainable development and efforts to eradicate
poverty”.392
275. The extent of the 1.5°C RCB is a key factor in formulating an NDC that is in line with
the principle of fairness, equity and CBRD-RC. To recall, the 1.5°C RCB represents
the total amount of emissions – i.e., the carbon budget – that the States, collectively,
can still emit to keep global warming to 1.5°C. As the pie chart in Figure 4 shows, the
RCB functions like a shared global resource – the red slice of pie functions like a shared
global resource that must be divided equitably among States in accordance with the
principle of fairness, equity and CBRD-RC, in light of past and present emissions, as
well as respective current levels of development and capabilities for tackling climate
change.
391 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
paras. 6, 7, 10 and 11.
392 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
paras. 5 and 6 (emphasis added). In the same Decision, the Parties “underscore[d] Article 2, paragraph 2, of
the Paris Agreement, which stipulates that the Agreement will be implemented to reflect equity and the
principle of common but differentiated responsibilities and respective capabilities, in the light of different
national circumstances” (para. 7).
89
Figure 10: The total carbon budget to limit global warming to 1.5°C (Sources: IPCC &
Global Carbon Budget)393
276. As a result, in preparing its NDC under Article 4.3, each State is obliged to determine
its own contribution to the Paris temperature goal, by allocating to itself an equitable
share of the 1.5°C RCB (i.e., the red slice) and, consequently, by setting an emissions
reduction target that will ensure that its future emissions remain within its equitable
share of that budget.394 If a State prepares an NDC that entails an inequitable share of
the carbon budget, it will violate Article 4.3 of the Paris Agreement.
393 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), p. 29; and Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth
System Science Data, 15(12), 5 December 2023 (available here), p. 5327. The updated 1.5°C RCB by
Friedlingstein et al. is based on the IPCC Sixth Assessment Report and a recent revision of the IPCC estimates.
See P. Forster et al., “Indicators of Global Climate Change 2022: Annual update of large-scale indicators of
the state of the climate system and human influence”, Earth System Science Data, 15(6) (2023) (available
here), pp. 2295-2327; R. Lamboll et al., “Assessing the size and uncertainty of remaining carbon budget”,
Nature Climate Change, 13 (8 June 2023) (available here), pp. 1360-1367.
394 Domestic courts have relied on the RCB in their reasoning on fair and appropriate national emission reduction
targets. See, for example, Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands,
13 January 2020, paras. 2.1 (recital 7), 4.6, 5.7.2-5.7.5, 5.7.8, 6.3, 6.5, 7.2.1-7.2.9 and 7.4.1-7.5.1 (available
here); German Constitutional Court, Neubauer et al. v. Germany, 24 March 2021, paras. 210-255 (available
here); Brussels Court of Appeal, VZW Klimaatzaak v. Kingdom of Belgium & Others, 30 November 2023,
paras. 184-202 (available here). In addition, in several countries, scientific advisory committees, established
by law to advise the government on climate action, have determined an equitable NDC based on a country’s
fair share of the RCB. For instance, in the EU, the European Scientific Advisory Board on Climate Change,
established by the European Climate Law of 2021, provides independent scientific advisory to the EU and
uses the RCB to calculate the EU’s fair share. In order to “deliver a contribution to achieving the temperature
Historical carbon budget
2400 ± 240 GtCO2
83%
Historical carbon budget
2550 ± 260 GtCO2
90%
90
277. The principle of fairness, equity and CBDR-RC imply that each developed State has to
reduce its anthropogenic emissions by 2030 by considerably more than the collective
targets aligned with the IPCC 1.5°C pathway. Otherwise, a developed State would emit
more than its equitable share. To emit its equitable share, a developing State, on the
other hand, may be permitted to set emission reduction targets that are less demanding
than the collective targets aligned with the IPCC 1.5°C pathway, depending on each
developing State’s past and present emissions, level of development and capabilities
for tackling climate change.
(d) The NDC must reflect the special dispensation for least
developed and small island developing States
278. Under Article 4.6 of the Paris Agreement, least developed countries and SIDS are given
special dispensation to prepare and communicate strategies, plans and actions that
reflect their “special circumstances”.
goal of the Paris Agreement that is both fair and consistent with the physical science of climate change”, the
ESABCC “recommends that the EU consider: [i] emission pathways consistent at the global level with limiting
warming to 1.5°C; and [ii] estimates of its fair share of the remaining global carbon budget consistent with
limiting global warming to 1.5°C”. Referring the Paris Agreement (e.g., “highest possible ambition”, and the
principle of CBDR-RC) and EU law, the ESABCC explained that “when deciding on its climate targets beyond
2030, the EU needs to communicate how it has considered its responsibility for climate change or climate
action, its capability to act and its national circumstances. As a party to a treaty in its own right, the EU has a
legal responsibility to pursue the achievement of the Paris Agreement temperature goal, and it shares this with
over 190 countries, each with different responsibilities, capacities and national circumstances.” On this basis,
the ESABCC recommends, for the EU, “a 2040 target of a reduction in emissions in the range of 90–95%
compared to 1990, corresponding to a budget of 11–14 Gt CO2e in 2030-2050” (see, ESABCC, “Scientific
advice for the determination of an EU-wide 2040 climate target and a greenhouse gas budget for 2030–2050”,
2023, pp. 14-15, 26 (available here)). In the UK, the UK Committee on Climate Change (“CCC”), established
under the UK Climate Change Act, advises the UK government on the UK carbon budget and UK NDC. The
CCC explains that “[t]he Paris Agreement requires that NDCs reflect each party’s highest possible ambition
and their [CBDR-RC]”, implying that the UK’s net zero GHG emission target for 2050 “is around two decades
earlier than when global GHG emissions reach Net Zero in emissions pathways assessed by the IPCC as
limiting warming to 1.5°C”. To this end, the UK CCC recommends that the UK achieve a reduction in GHG
emissions of at least 68 percent by 2030 (from 1990) and of 78 percent by 2035 (from 1990) (see Committee
on Climate Change, “The Sixth Carbon Budget, the UK’s path to Net Zero”, December 2020, pp. 316, 338,
and 370 (available here)). Similarly, in New Zealand, the Climate Change Commission advised its
government in 2021 that its NDC “was not compatible with contributing to limiting warming to 1.5°C”. It
advised that “[a]s a developed country, Aotearoa[/New Zealand] has agreed to ‘take the lead’”, “the NDC
needs to reflect deeper emission reductions than the global average necessary”, and “that the NDC should
reflect emissions much lower than just aligning with the middle of the IPCC interquartile range” (see He Pou
a Rangi Climate Change Commission, “Ināia tonu nei: a low emissions future for Aotearoa Advice to the New
Zealand Government on its first three emissions budgets and direction for its emissions reduction plan 2022 –
2025”, 31 May 2021, p. 357 (available here)). As a final example, in Germany, the German Advisory Council
on the Environment encouraged the German government to clarify its emissions reductions targets in 2020
noting that the RCB calculated on the basis of national climate protection targets was twice as high as its own
RCB calculations based on Germany’s compliance with the Paris Agreement (see German Advisory Council
on the Environment, “Umweltgutachten 2020: Für eine entschlossene Umweltpolitik in Deutschland und
Europa“, 2020, pp. 47 and 55 (available here)).
91
279. As COP Decision 4/CMA.1 shows, this provision also has a bearing on the NDCs
prepared by all other States: in addressing fairness and equity, this COP Decision
requires each State to explain how it has prepared an NDC for itself that “has
addressed” this differentiation in favour least developed countries and SIDS.395
280. Again, therefore, this aspect of fairness and equity must be assessed on a relative basis,
i.e., the “special circumstances” of a State must be assessed relative to the position of
other States, including LDCs and SIDS.396 States will violate Article 4.3 if they do not
do so.
(e) The NDC must be informed by the COP global stocktake
281. Article 4.9 of the Paris Agreement provides that, in communicating their NDCs, Parties
“shall … be informed by the outcomes of the Global Stocktake referred to in
Article 14.” Accordingly, in preparing an NDC, a State must weigh the significance of
the available COP Global Stocktake reports.
282. The first COP Global Stocktake Decision, of December 2023, concluded that NDCs are
collectively insufficient to secure the Paris temperature goal and prevent dangerous
anthropogenic interference with the climate system. Specifically, looking backward,
the Parties “note[d] with concern the pre-2020 gaps in both mitigation ambition and
implementation by developed country Parties and that the [IPCC] had earlier indicated
that developed countries must reduce emissions by 25–40 per cent below 1990 levels
by 2020, which was not achieved”.397
283. Looking forward, the COP Global Stocktake notes that the “Parties are not yet
collectively on track towards achieving the purpose of the Paris Agreement and its longterm
goals”.398 As a result, the Parties “expresse[d] concern that the carbon budget
395 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision, para. 6.
396 As explained above, the 1.5°C RCB represents the total amount of emissions that all States together can still
emit to keep global warming to 1.5°C. The 1.5°C RCB must be distributed among States based on the principle
of fairness, equity and CBDR-RC. This implies that, to prepare its NDC, each State has to determine its
equitable share of the 1.5°C RCB, taking into account how much other States, including least developed
countries and SIDS, are still permitted to emit.
397 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 17 (emphasis added).
398 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 2.
92
consistent with achieving the Paris Agreement temperature goal is now small and being
rapidly depleted”.399 The Parties, therefore, stated, “with significant concern”, that
“there is a rapidly narrowing window for raising ambition and implementing existing
commitments in order to achieve it”.400 The Parties noted that “significantly greater
emission reductions are required to align with [the Paris temperature goal]”.401 Today,
therefore, the “highest possible ambition” for an NDC, and its “progression”, under
Article 4.3 of the Paris Agreement must reflect the fact that very little remains of the
carbon budget in order to hold global warming to 1.5°C. At the rate of current
emissions, the carbon budget will be completely exhausted in just six years.402
284. Pursuant to Article 4.9, a State must take this outcome of the COP Global Stocktake
into account in preparing its subsequent NDCs. As a result, to ensure that NDCs
collectively are capable of meeting the collective objectives of the Paris Agreement,
States must individually raise the level of their ambition. They will violate Article 4.3
if they fail to do so.
(f) Summary of required considerations in setting the level of an
NDC
285. In sum, Article 4.3 of the Paris Agreement requires that a State address five factors
when “prepar[ing]” its NDC:
• Best available science: A State must prepare its NDC based on the best available
science;
• Highest possible ambition, and a progression: A State must prepare its NDC in a
way that accelerates mitigation efforts through rapid, deep and sustained emission
reductions, reflecting the “highest possible ambition”. Given the 1.5°C RCB, this
requires, in practice, that a State prepare an NDC to reduce, collectively, emissions
by considerably more than 43 percent by 2030, 60 percent by 2035, 69 percent by
2040, and 84 percent by 2050, compared with 2019 levels, and achieve net zero
CO2 emissions well before early 2050 and net zero GHG emissions well before
early 2070.
399 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 25.
400 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 24 (emphasis added).
401 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 21 (emphasis added).
402 See, sub-section II.B.4.
93
• The principle of fairness, equity and CBDR-RC: A State must prepare an NDC
that respects fairness, equity and the principle of fairness, equity and CBDR-RC.
This requires, in practice, that each State prepare its NDC which reduces emissions
according to its equitable share of the 1.5°C RCB.
• Special dispensation for LDCs and SIDS: LDCs and SIDS are given special
dispensation to prepare and communicate strategies, plans and actions that reflect
their “special circumstances”; while other States must prepare an NDC that
addresses this differentiation in favour of LDCs and SIDS.
• Informed by the Global Stocktake Decision: A State must prepare its NDCs taking
into account the outcome of the First Global Stocktake Decision. In light of this
outcome, a State must prepare its NDC with an increased level of ambition, in order
to meet the Paris temperature goal and prevent dangerous anthropogenic
interference with the climate system.
iii. States shall communicate a nationally determined
contribution
286. Under Article 4.2, the second obligation regarding NDCs is that States “shall”
“communicate” their respective and successive 5-yearly NDCs. Article 4.8 adds a
further mandatory obligation: in communicating their NDCs, States “shall provide the
information necessary for clarity, transparency and understanding” in accordance with
“any relevant” COP Decisions.
287. As noted above, COP Decisions have elaborated on the specific information needed to
ensure “clarity, transparency and understanding”.403 In addressing obligations relating
to the preparation of an NDC, Antigua and Barbuda has already referred to several
aspects of Annex I of Decision 4/CMA.1, which is the most recent COP Decision under
Article 4.8 of the Paris Agreement regarding information on NDCs. Antigua and
Barbuda notes that, pursuant to Decision 4/CMA.1, Parties “shall” provide the
following specific information when communicating their NDC:
• Quantifiable information on the reference point (including, as appropriate, a base
year);
• Time frames and/or periods for implementation;
• Scope and coverage;
403 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision.
94
• Assumptions and methodological approaches, including those for estimating and
accounting for anthropogenic greenhouse gas emissions and, as appropriate,
removals;
• How the Party considers that its nationally determined contribution is fair and
ambitious in the light of its national circumstances; and,
• How the nationally determined contribution contributes towards achieving the
objective of the Convention as set out in its Article 2.404
288. To meet the requirements of “clarity”, “transparency”, and “understanding” under the
“communicate” limb of Article 4.3, States must address these topics in a manner that
ensures that each of the points enumerated in the Decision is sufficiently
comprehensible. They will violate Article 4.3 if they fail to do so.
iv. States shall maintain a nationally determined
contribution
289. Under Article 4.2, the third obligation regarding NDCs is that States “shall” “maintain”
their NDCs.
290. The ordinary meaning of the word “maintain” means “to support or uphold in an action”
and “[t]o keep up, preserve, cause to continue in being ... ; to keep vigorous, effective,
or unimpaired.”405 The verb “maintain”, therefore, speaks to an obligation to sustain
an intended NDC over its 5-year lifetime. An NDC can be sustained over time only if
a State takes sufficient action over the 5-year period to achieve the target, which reflects
no more than an equitable share of the available carbon budget, as discussed above.
291. If insufficient action were taken, an NDC would quickly cease to provide a good faith
statement of the State’s emissions reduction target, which would violate the obligation
to “maintain” an NDC throughout its life.406 This is because, absent timely action, the
NDC would rapidly become an unachievable, misleading, empty vessel.
292. The text of the Paris Agreement confirms that a State is under an obligation to take
sufficient action to achieve an NDC. The second sentence of Article 4.2 provides that
404 UNFCCC COP, Decision 4/CMA.1, “Further guidance in relation to the mitigation section of decision
1/CP.21” (2018) (available here), Annex I to the Decision. This COP Decision is relevant to the interpretation
of Articles 4.2 and 4.8 of the Paris Agreement as explained in footnote 372 above.
405 Oxford English Dictionary, “maintain v.” (available here) (emphasis added).
406 VCLT, Article 26.
95
“Parties shall pursue domestic mitigation measures, with the aim of achieving the
objectives of such contributions”. The highlighted words require States to take diligent
action, in the form of “measures”, with the purpose of achieving their NDC.
293. Other provisions of the Paris Agreement support the position that States must take
action:
• Article 3 provides that States are “to undertake … ambitious efforts” to achieve the
purposes of the Agreement.
• Article 4.1 provides that States “aim” to reduce current emissions to reach global
peaking “as soon as possible”, and to undertake rapid reductions thereafter.
• Article 4.2, in its first sentence, provides that an NDC must be a contribution that a
State “intends to achieve”.
294. The language in these provisions expresses a due diligence obligation that requires
States to take all measures at their disposal to achieve their NDC, taking into account
equity and the principle of fairness, equity and CBDR-RC. Under a due diligence
obligation, States must take “all the means at [their] disposal” to do so.407 Determining
whether a State has undertaken sufficient action to “maintain” its NDC for the purpose
of compliance with Article 4.2 is therefore determined according to whether it has met
this due diligence standard.
295. The existence of such an obligation to take diligent action to achieve an NDC is
consistent with the object and purpose of the Paris Agreement, which is to achieve the
Paris temperature goal and prevent dangerous anthropogenic interference with the
climate system. If States were under no obligation to take action to achieve their
intended NDCs – and therefore make no contribution to preventing dangerous
anthropogenic interference with the climate system – the object and purpose of the Paris
Agreement would be wholly defeated.408
407 Pulp Mills, p. 56, para. 101.
408 Indeed, the Court has repeatedly interpreted treaty provisions in a manner that gives effect to, rather than
defeats, the object and purpose of the treaty. See, e.g., Application of the Convention on the Prevention and
Punishment of the Crime of Genocide (Bosnia and Herzegovina v. Serbia and Montenegro), Judgment, I.C.J.
Reports 2007 (hereinafter “Bosnia Genocide”), p. 111, para. 162 and p. 113, para. 166; Military and
Paramilitary Activities in und against Nicaragua (Nicaragua v. United States of America), Merits, Judgment,
I.C.J. Reports 1986 (hereinafter “Military and Paramilitary Activities”), p. 148, para. 292, dispositif, para. 10,
finding that the United States had “committed acts calculated to deprive of its object and purpose the Treaty
of Friendship, Commerce and Navigation between the Parties”.
96
296. Below, Antigua and Barbuda addresses the contours of the due diligence obligations
arising under customary international law in the context of climate change,409 which
informs the required conduct in the context of the Paris Agreement. In short, the level
of diligence must be appropriate and proportionate in light of the severity and likelihood
of the harm arising, and it must be differentiated across States according to their
capabilities, consistent with equity and the principle of fairness, equity and CBDR-RC.
297. In sum, the obligation to “maintain” an NDC in Article 4.2 requires that States take
action to achieve their NDCs that meets the threshold of diligence required, namely that
it constitutes all means at their disposal to meet their NDC. States will violate their
obligations under Article 4.3 where they fail to take diligent action to achieve their
NDCs, including holding their emissions within the levels foreseen in the NDC and
exploiting no more than an equitable share of the 1.5°C RCB.
b. Obligations arising under the customary international law
obligation of prevention
i. Climate change triggers the customary international law
obligation of prevention
298. The risk of significant harm to the environment caused by anthropogenic GHG
emissions triggers a State’s customary international law obligation to prevent
significant harm to the environment. To comply with this obligation in the specific
context of climate change, States are under a due diligence obligation to adopt rapid,
deep and sustained emissions reduction measures sufficient to prevent significant
environmental harm, consistent with fairness, equity and CBDR-RC.
299. In Section III.B.1 above, Antigua and Barbuda set out the elements of this customary
obligation.
300. First, the obligation applies in respect of any activity planned or carried out in the
territory of a State, or otherwise within a State’s jurisdiction or control. In the context
of climate change, the “activity” in question is industrial or another anthropogenic
activity (e.g., deforestation) that release GHG emissions.
409 See, paras. 305-342, below.
97
301. Second, the relevant activities must cause, or risk causing, significant harm to the
environment. In Section II.B.4 above, Antigua and Barbuda addresses the causal
connection between anthropogenic GHG emissions and atmospheric warming, noting
that there is a near-linear relationship between the two: each 1,000 GtCO2 emissions
causes a temperature increase of between 0.27°C to 0.63°C.410
302. The associated environmental harms are similarly linear: environment harm is already
occurring as a result of global warming, which has reached on average 1.1°C to
1.35°C,411 compared with pre-industrial levels and, with every incremental degree of
warming, environmental harm worsens.
303. There can also be no question that the harms in question are “significant”. Recall that
the threshold for “significant” is “something more than ‘detectable’”, but does not need
to be at the level of “‘serious’ or ‘substantial’”. It is evident on the basis of a wellestablished
international scientific consensus – as set out in Section 0 – that the harms
of climate change are well beyond “detectable” and, indeed, rise to the level of
“serious” or “substantial”.
304. Third, the harms must be transboundary in nature. By their nature, the environmental
harms arising from climate change are transboundary. Harm originates from the release
of GHG emissions in one place, with the emissions cumulating in the atmosphere and
being absorbed by the oceans, leading to increased land and ocean temperatures, sea
level rise and ocean acidification. Evidently, these harms are not confined to the
territory of the State where the emissions are released, but are inherently transboundary.
ii. Substantive obligations
305. As explained above, the customary obligation of prevention has a positive and proactive
character, translating into a duty of due diligence: a State must deploy all the means at
its disposal to avoid activities taking place under its jurisdiction from causing
410 IPCC, Sixth Assessment Report, 2021, The Physical Science Basis (Working Group I), Summary for
Policymakers (available here), para. D. 1.1. See, generally Section 0, above.
411 See, sub-section II.B.4, above.
98
significant environmental harm to another State’s territory or to areas beyond national
jurisdiction.412
306. In the context of climate change, certain features of the due diligence obligations bear
emphasis. These relate to: (1) the measures that States must take to comply with due
diligence in the circumstances; (2) the level of due diligence must be appropriate and
proportional to the risks of climate change; and (3) the level of due diligence in light of
the different capabilities and responsibilities of States (in an expression of the principle
of fairness, equity and CBDR-RC).
307. These same factors relating to due diligence under the customary obligation of
prevention, as well as the analysis of these factors below, are relevant to the
conventional sources of law addressed elsewhere in this Written Statement, to the extent
that these conventional sources establish due diligence obligations.
(1) Measures required to comply with due diligence in the circumstances
308. To discharge its customary obligation of prevention, a State must deploy all the means
at its disposal, exercise best possible efforts, and do the utmost to prevent harm. To
meet this obligation requires a range of conduct by a State:
Not only the adoption of appropriate rules and measures, but
also a certain level of vigilance in their enforcement and the
exercise of administrative control applicable to public and
private operators, such as the monitoring of activities undertaken
by such operators ….413
309. In the context of climate change mitigation, a first feature of due diligence requires
States to adopt “appropriate rules and measures”, which include those that lead to a
rapid, deep and sustained reduction in emissions emanating from activities within the
jurisdiction and control of the State.
310. In that regard, as set out above, the IPCC has undertaken a thorough analysis of the
“appropriate rules and measures”, including their likely impact on emissions, as well as
412 See, Rio Declaration, Principle 2; see also, Pulp Mills, p. 56, para. 101.
413 Pulp Mills, p. 79, para. 197, and see p. 56, para. 101. See also, Bosnia Genocide, p. 221, para. 430; IUU
Advisory Opinion, p. 40, para. 129, citing to Responsibilities in the Area, p. 41, para. 110.
99
the relationship between their cost and their efficacy in reducing emissions.414
Satisfying due diligence obligations in the circumstances requires States to adopt such
measures.
311. The UNFCCC has identified “sufficient cost-effective opportunities to address the 2030
emissions gap”.415 The IPCC’s Synthesis Report from the Sixth Assessment Cycle
finds that “several mitigation options” are “technically viable”, “increasingly cost
effective” and “generally supported by the public”. Indeed, in some regions and
sectors, “maintaining emissions-intensive systems may [] be more expensive than
transitioning to low emissions systems”.416
312. The COP Global Stocktake Decision similarly finds that “feasible, effective and lowcost
mitigation options are already available in all sectors to keep 1.5 °C within reach
in this critical decade with the necessary cooperation on technologies and support”.417
The availability of these mitigation options speaks to whether States have met their due
diligence obligation: if “feasible, effective, and low-cost mitigation options” are
available, and States have not adopted those measures, this would indicate that they are
not taking “all means at their disposal” to reduce their emissions.
313. As a second feature of due diligence, States must also act with requisite vigilance to
“enforce” the measures to ensure their efficacy in practice. The enforcement of the
measures includes exercising sufficient administrative control with respect to the
operators engaging in the emission-generating activities that trigger the obligation,
which includes adequate monitoring of the activities.
314. A failure to act with diligence in adopting and enforcing appropriate mitigation
measures, as elaborated below, would constitute a breach of the customary obligation
of prevention.
414 See, sub-section II.D.2.
415 See, UNFCCC, “Technical dialogue of the first global stocktake” (2023) (available here), para. 14.
416 IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Summary for
Policymakers (available here), p. 11, A.4.2.
417 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 16(c).
100
(2) Level of diligence must be appropriate and proportional to the risks of
climate change
315. It is well accepted that due diligence is a “variable concept”.418 Specifically, the level
of required due diligence varies based on:
316. First, the greater the level of risk, the greater the level of due diligence required to
address it. This includes both the likelihood of the risk arising and the severity of the
resulting harms; as one tribunal put it, “the standard of due diligence has to be more
severe for riskier activities”.419
317. Second, the evolving knowledge about a particular risk; additional knowledge
(through scientific research) may highlight that the likelihood of a particular risk
materialising is higher than previously thought (again including both likelihood of risk
and severity of resulting harms); or it may reveal some previously unknown dimension
of the risk. Conduct that is “considered sufficiently diligent at a certain moment may
become not diligent enough”, as the circumstances evolve.420
318. These elements are particularly pertinent in the context of climate change.
319. As a first point, Antigua and Barbuda notes that States’ obligation to act diligently in
the context of climate change arose a considerable time ago, because the harmful
impacts of anthropogenic emissions on the climate system have been known for some
time. From the time when States first became aware of the risk that anthropogenic
GHG emissions might cause significant harm to the climate system, they were under
an obligation to take diligent action to prevent such harm, in light of the degree of
knowledge and risk, the level of their emissions, and the means at their disposal.
320. Human understanding of the harms of anthropogenic GHG emissions continues to
grow. Knowledge emerging this very year indicates that the risks to the environment
and humans from climate change are even worse than expected.421 The Earth is
warming faster, and the consequences are more severe, than previously anticipated.
418 See, Responsibilities in the Area, p. 43, para. 117.
419 See, footnote 418, above.
420 See, footnote 418, above.
421 See, sub-section II.C.1 and Figure 5, above.
101
321. Indeed, today, knowledge as to the rate and consequences of global warming is
considerably more developed than it was in 2015, when the Paris Agreement was
finalised. For example: the most recent data post-dating the IPCC’s initial Sixth
Assessment shows that the 1.5°C RCB is significantly smaller than previously assessed;
indeed, the remaining carbon budget is now vanishingly small.422 That is, the most
recent data shows that the 1.5°C RCB from the beginning of 2024 is almost half of the
1.5°C RCB from the beginning of 2020, as previously estimated by the IPCC.423
Further, even at current levels of warming, the adverse effects of climate change are
worse than expected.
322. Knowledge is also increasing as to the range of available, cost-effective mitigation
measures which have become “technically viable” in the years since 2015.424
323. Given the latest information, the level of diligence required today exceeds the alreadyhigh
level of due diligence that might have been acceptable in 2015 (and previously).
As the window of opportunity to prevent catastrophic harm narrows, the level of due
diligence required increases.
324. It is also highly pertinent that the threat posed by climate change is unprecedented in
human history and, as robust internationally accepted science shows, has long passed
from theoretical to real. The risks – to biodiversity, ecosystems, and habitats; to human
culture and ways of life; and to the very continued existence of some SIDS – are literally
existential. Under some worst-case scenarios, factoring in irreversible tipping points
and scientific uncertainty, including uncertainty as to the ceiling of possible warming,
the continuation of life on earth as we know it is at stake.425
325. No previous tribunal has been called on to articulate the conduct required in response
to a risk of the nature, severity and urgency of that presented, today, by climate change.
The level of due diligence demanded of States must match the scale of the crisis.
422 Pierre Friedlingstein et al., “Global Carbon Budget 2023” in Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5304.
423 See, sub-section II.B.4, paras. 44-46, above.
424 See, IPCC, Sixth Assessment Report, 2023, Synthesis Report (Working Groups I, II and III), Full Report
(available here), p. 10; see also, UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global
stocktake” (2023) (available here), para. 30.
425 See, sub-section II.C.1, above.
102
326. In that respect, it is axiomatic that, under the customary obligation of prevention, in
determining how to formulate a target for emissions reductions, a State cannot settle for
reductions that it knows, with scientific certainty, would still lead to significant harm.
The duty of each State is to take all measures necessary to prevent harm.
327. As a result, States cannot simply formulate a target by reference to the Paris Agreement
goal of limiting global warming to 1.5°C, because warming to this extent will, as the
IPCC has found with very high probability, entail significant harm.426 States must,
therefore, employ all of the means at their disposal and do their utmost to cut emissions
to a level that will minimise global warming, taking into account the most recent data.
Antigua and Barbuda elaborates further on these obligations in the next sub-section.
(3) The level of due diligence is differentiated between and among States
328. The obligation to act with due diligence to prevent significant environmental harm is
qualified, under customary international law, by the capabilities of the State. States
must take all means at their disposal (exercise best possible efforts, do the utmost).
Thus, the due diligence obligation is qualified by what is possible for each State, i.e.,
by its capabilities. In this regard, the parties to the Paris Agreement have acknowledged
that “feasible, effective and low-cost mitigation options” are available to States.427
329. In practice, developed States – which have higher capabilities – must engage in more
demanding conduct than developing States to fulfil their due diligence obligations.
330. This differentiation in terms of the required conduct is in line with the principle of
fairness, equity and CBDR-RC, which applies in the context of climate change.
331. Although Antigua and Barbuda considers that the Paris Agreement temperature goal
does not go far enough to prevent significant harm, it has been used by the IPCC to
establish scientifically-based standards for mitigation action by States. The IPCC’s
work is, therefore, useful in clarifying the extent of a State’s obligations to prevent the
adverse impacts of climate change.
426 See, sub-sections II.C.2 and II.C.3.
427 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 16(c).
103
332. As explained above, in 2021, the IPCC established a minimum emission reduction
pathway to hold global warming to 1.5°C, with no or limited overshoot. Under this
pathway, given the 1.5°C RCB, States must collectively reduce emissions by at least
43 percent by 2030, 60 percent by 2035, 69 percent by 2040, 84 percent by 2050,
compared with 2019 levels; reaching net zero CO2 emissions by early 2050; and net
zero GHG emissions by early 2070 (“collective targets aligned with the IPCC 1.5°C
pathway”). The most recent data shows that, to keep global warming to 1.5°C, States,
collectively, have to reduce their emissions by considerably more than the collective
targets aligned with the IPCC 1.5°C pathway.428
333. In light of the IPCC’s scientific work, while taking account of the most recent scientific
evidence on the RCB, and without prejudice to States’ historic obligations, States must
now take diligent action to formulate and implement an emissions reduction plan that
makes a sufficient national contribution to reducing collective emissions in order to
limit global warming, at a minimum, to 1.5°C.
334. In line with their greater capabilities to reduce emissions, their greater current and
historic emissions, and in keeping with the principle of fairness, equity and CBDR-RC,
developed countries must take the lead in reducing emissions, with broader, deeper and
faster reductions than developing countries.
335. As explained above, this means that developed countries must reduce their emissions
by considerably more than the collective targets aligned with the IPCC 1.5°C pathway.
These targets are collective targets, i.e., for all States collectively. To ensure that each
State emits its equitable share of the 1.5°C RCB, each developed State has to reduce its
emissions by more than the collective targets, in order to allow developing States to
reduce their emissions by less. Otherwise, the required diligent conduct is not
differentiated appropriately between and among States, contrary to the obligation of
prevention, and fairness, equity and CBDR-RC.
336. In formulating and implementing an emissions reduction pathway, States must also act
with diligence to ensure that they plan to exploit, and end up exploiting, no more than
an equitable share of the 1.5°C RCB. As already noted, this RCB functions like a shared
428 See, Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12),
5 December 2023 (available here), p. 5304. See also, sub-section II.B.4, para. 45, above.
104
global resource that can be exploited by States through economic activities to further
sustainable development, and eradicate poverty, and must be divided equitably among
States.
337. States violate the customary obligation of prevention if they fail to take diligent action
to formulate and implement an emissions reduction plan that makes a sufficient and
equitable national contribution to reducing collective emissions in order to limit global
warming, at a minimum, to 1.5°C.
(4) Summary of substantive obligations
338. From the time when States first became aware of the risk that anthropogenic GHG
emissions might cause significant harm to the climate system, they were under an
obligation to take diligent action to prevent such harm, in light of the degree of
knowledge and risk, the level of their emissions, and the means at their disposal. To
the extent a State has failed to do so, the State has violated the customary international
law obligation of prevention.
339. Looking forward, for the reasons explained above, a developed State fails to respect the
customary obligation of prevention if the State does not do its utmost, using all the
means at its disposal, to reduce its emissions by considerably more than the collective
targets aligned with the IPCC 1.5°C pathway. Specifically, a developed State must do
its utmost, using all the means at its disposal, to reduce its emissions by considerably
more than 43 percent by 2030, 60 percent by 2035, 69 percent by 2040, and 84 percent
by 2050, compared with 2019 levels, and achieve net zero CO2 emissions well before
early 2050 and net zero GHG emissions well before early 2070.
340. A developed State must reduce its emissions by considerably more than the collective
targets aligned with the IPCC 1.5°C pathway for, at least, three reasons:
(a) The first reason is that a State must reduce its emissions taking into
account its equitable share of the 1.5°C RCB, in order to respect the
principle of fairness, equity, and CBDR-RC. The need to apportion the
collective targets aligned with the IPCC 1.5°C pathway in light of each
State’s equitable share, implies that each developed State has to reduce
105
its emissions by more than the collective targets, in order to allow
developing States to reduce their emissions by less.
(b) The second reason is that, when setting its emission reduction targets, a
State must take into account the most recent scientific evidence,
reflecting the most recent knowledge about, among others, the RCB.
The most recent data shows that the 1.5°C RCB, available from the
beginning of 2024, is almost half of the IPCC’s 1.5°C RCB, available
from the beginning of 2020.429 With a vanishing 1.5°C RCB, States must
accelerate their mitigation efforts to keep global warming to 1.5°C.
(c) The third reason is that, when setting its emission reduction targets, a
State must take into account that anthropogenic emissions cause
significant environmental harm at levels below the 1.5°C
temperature increase. The collective targets aligned with the IPCC
1.5°C pathway seek to hold global warming to 1.5°C. When setting its
emission reduction targets, a State must take into account that significant
harm occurs at lower temperature increases, in particular to vulnerable
developing States, such as Antigua and Barbuda and other SIDS.430
341. For these reasons, individually and collectively, a developed State must set emission
reduction targets that are considerably lower than the collective targets aligned with the
IPCC 1.5°C pathway. If a developed State fails to do so, the State violates the
prevention obligation.
342. For a developing State, the emission reduction targets must be determined in light of
the same considerations ((a), (b), (c), above). To emit its equitable share, a developing
State may be permitted to set emission reduction targets that are less demanding than
the collective targets aligned with the IPCC 1.5°C pathway, depending on each
developing State’s past and present emissions, level of development and capabilities
for tackling climate change.
429 Pierre Friedlingstein et al., “Global Carbon Budget 2023”, Earth System Science Data, 15(12), 5 December
2023 (available here), p. 5304.
430 See, sub-section II.C.2, para. 50.
106
iii. Procedural obligations
343. As Antigua and Barbuda has explained, States have an obligation to cooperate,
especially through notification and consultation with potentially affected States. States
who are “potentially affected” are those States whose territory may be harmed by
activities occurring in the jurisdiction of the original State.
344. In the context of climate change, all States are potentially affected. Thus, within the
global community of States, each State bears an obligation to cooperate with others. In
practice, this means the customary obligation of cooperation can only be discharged
through appropriate bodies fit for that purpose, namely bodies with close to universal
membership, dedicated to coordinating the global response to climate change. Today,
the primary such bodies are established under the UNFCCC.
345. In assessing what precise conduct is required under the obligation to cooperate –
including, for example, how to assess the adequacy of consultations – regard must be
had to the overarching purpose of the obligation, i.e., the prevention of environmental
harm.
346. In the context of climate change, Antigua and Barbuda has explained that, to act with
diligence in the prevention of harm, States must equitably divide the 1.5°C RCB
amongst themselves. This has consequences for States’ cooperative efforts;
specifically, they must cooperate to ensure that, in setting emissions reduction targets
to minimise the impact of climate change, the 1.5°C RCB is indeed divided equitably.
c. Obligations arising under international human rights law
347. As Antigua and Barbuda has explained above, the impact of climate change on human
rights is profound and uncontested; it is “potentially the greatest threat to human rights
in the twenty-first century”.431
348. The impacts of climate change, as established by the IPCC, directly and unambiguously
impinge adversely upon individuals’ human rights, including the rights to life, health,
adequate food and water, adequate housing and self-determination. States are,
therefore, under an obligation to respect, promote and satisfy these and other human
431 See, Mary Robinson, “Why climate change is a threat to human rights”, TED Women, May 2015 (available
here).
107
rights against the actual and threatened impacts of climate change. Antigua and
Barbuda explains in turn the scope and substance of these human rights obligations.
i. The scope of human rights obligations
349. Human rights treaties have differing scopes of territorial application. Some human
rights treaties, like the ICESCR, leave open their scope of territorial application,
whereas others, such as the ICCPR, explicitly limit the scope of application to
individuals within the territory (or otherwise under the jurisdiction).
350. For treaties that leave open the scope of territorial application, the UN Committee on
Economic, Social, and Cultural Rights (“CESCR”) has explained that, under the
ICESCR, “States parties are required to respect, protect and fulfil all human rights for
all. They owe such duties not only to their own populations, but also to populations
outside their territories, in accordance with Articles 55 and 56 of the Charter of the
United Nations.”432
351. For human right treaties that limit the scope of territorial application to the parties’ own
territory or jurisdiction, State parties have obligations to protect those human rights of
populations inside their territory.433 However, their obligations do not stop here, in case
activities on their territory cause environmental harm outside their territory.
352. The Inter-American Court of Human Rights (“IACHR”) explained that persons outside
the territory of the State of origin – that is the State where the polluting activity takes
place – “are under the jurisdiction of the State of origin”, if there is “a causal link”
between the polluting activity on its territory and the infringement of human rights of
the persons outside its territory.434 The State of origin is obliged to respect and to ensure
432 UN Committee on Economic, Social and Cultural Rights, “Climate change and the International Covenant on
Economic, Social and Cultural Rights”, UN Doc. E/C.12/2018/1, 31 October 2018 (available here), para. 5
(emphasis added), citing General comment No. 24, State obligations under the International Covenant on
Economic, Social and Cultural Rights in the context of business activities, para. 27.
433 Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion,
I.C.J. Reports 2004 (hereinafter “Wall Advisory Opinion”), pp. 178-180, paras. 108-111.
434 IACHR Advisory Opinion, para. 101 (emphasis added); see also, Committee on the Rights of the Child, Sacchi
v. Argentina et al., 10 August 2021, pp. 10-12, paras. 10.5-10.7. The decisions in the Sacchi case were handed
down in separate documents for each State party; for ease of reference, the paragraph references provided in
this Written Statement are to Sacchi v. Argentina (UN Doc. CRC/C/88/D/105/2019); the cited paragraphs are
identical across the decisions provided for other State parties.
108
the human rights of these persons outside their territory, because these persons fall
within its jurisdiction.435
353. The IACHR reasoned that “it is the State in whose territory or under whose jurisdiction
the activities were carried out that has the effective control over [the activities] and is
in a position to prevent [these activities] from causing transboundary harm that impacts
the enjoyment of human rights of persons outside its territory.”436 The IACHR
continued that “[t]he potential victims of the negative consequences of such activities
are under the jurisdiction of the State of origin for the purposes of the possible
responsibility of that State for failing to comply with its obligation to prevent
transboundary damage.”437
354. These findings are particularly pertinent in the context of climate change. Climate
change does not respect national boundaries. Emissions occurring as a result of
activities in one State may very well adversely impact the enjoyment of human rights
of persons outside its territory. Indeed, “climate change has an adverse effect over the
enjoyment of rights by individuals both within as well as beyond the territory of the
State party.”438
355. States are under an obligation to protect the human rights of persons outside their
territory, if emissions from activities on their territory have a causal impact on the
enjoyment of these persons’ human rights.
ii. The substance of human rights obligations
356. Given the extensive actual and threatened impacts of climate change on the enjoyment
of human rights, States are under an obligation to adopt mitigation measures in order to
fulfil their obligations under human rights treaties.
435 See also, IACHR Advisory Opinion, para. 104(c).
436 IACHR Advisory Opinion, para. 102. The IACHR also explained that a State “should not act in a way that
hinders” other States that are party to the same treaty from complying with their human rights obligations,
with regard to their populations. The IACHR found that this obligation follows from the pacta sunt servanda
principle, which requires the parties to a treaty obligation to apply it “in a reasonable way and in such a manner
that its purpose can be realized”. See, IACHR Advisory Opinion, paras. 94, 101 and 102.
437 IACHR Advisory Opinion, para. 102 (emphasis added).
438 Committee on the Rights of the Child, Sacchi v. Argentina et al., 10 August 2021, para. 10.9.
109
357. Human rights bodies, and domestic courts, have clarified important aspects of a State’s
human rights obligations in relation to mitigation action to address climate change.
358. That is, to respect their obligations under human rights law in relation to mitigation, a
State must adopt effective mitigation measures: (1) reflecting its highest possible
ambition and the precautionary principle; (2) based on the best available science; and
(3) based on fairness, equity and CBDR-RC. Antigua and Barbuda discusses each
obligation in turn.
(1) To respect its human rights obligations, a State must adopt effective
mitigation measures, reflecting its highest possible ambition and the
precautionary principle
359. As the Human Rights Council’s special procedure mandate-holders explained, human
rights treaties require States “to adopt the mitigation measures necessary to reduce
global emissions so as to hold the increase in global temperature below levels that
would cause widespread harm to the enjoyment of human rights.”439
360. Other human rights treaty bodies have confirmed that States have obligations under
human rights treaties to adopt robust mitigation measures. Specifically, in a joint
statement, five UN human rights bodies440 explained that, “[i]n order for States to
comply with their human rights obligations, and to realise the objectives of the Paris
Agreement, they must adopt and implement policies aimed at reducing emissions,
which reflect the highest possible ambition.”441
361. The CESCR noted, in 2018, that the “[NDCs] that have been announced so far are
insufficient to meet what scientists tell us is required to avoid the most severe impacts
of climate change”.442 As a result, “[i]n order to act consistently with their human rights
obligations, NDCs should be revised to better reflect the ‘highest possible ambition’
439 Open Letter from UN Special Procedures Mandate-Holders, “A New Climate Change Agreement Must Include
Human Rights Protection for All”, 17 October 2014 (available here), p. 3 (emphasis added).
440 These bodies are: the Committee on the Elimination of Discrimination against Women; the Committee on
Economic, Social and Cultural Rights; the Committee on the Protection of the Rights of All Migrant Workers
and Members of their Families; the Committee on the Rights of the Child; and, the Committee on the Rights
of Persons with Disabilities. These are collectively referred to below as “CEDAW et al.”
441 CEDAW, et al., Joint Statement on “Human Rights and Climate Change” (16 September 2019) (available
here), para. 2.
442 UN Committee on Economic, Social and Cultural Rights, “Climate change and the International Covenant on
Economic, Social and Cultural Rights”, E/C.12/2018/1, 31 October 2018 (available here), para. 6.
110
referred to in the Paris Agreement”.443 As Human Rights Committee Member, Gentian
Zyberi, explained in his concurring opinion in Billy et al. v. Australia (2022), States are
required “to set their national climate mitigation targets at the level of their highest
possible ambition and to pursue effective domestic mitigation measures with the aim of
achieving those targets.”444
362. These statements make clear that, to respect their human rights obligations, States
“must adopt and implement” mitigation measures reflecting “the highest possible
ambition”; and, if they have not yet done so, States must strengthen their NDCs to meet
their human rights obligations.
363. States must also take into account the precautionary principle, which warrants more farreaching
mitigation measures. The IACHR has clarified that, in order to protect the
right to life and to personal integrity, even in the absence of scientific certainty, States
are required to take “effective” measures to prevent severe and irreversible damage,
according to the precautionary approach.445
364. The Dutch Supreme Court, in Urgenda, applied this reasoning in the context of the
serious and irreversible damage caused by climate change. The Court observed that,
even with global warming at levels below 1.5°C or 2°C, dangerous climate change may
occur. The precautionary principle, therefore, implies that “more far-reaching
measures should be taken to reduce greenhouse gas emissions, rather than less farreaching
measures.”446
365. Similar to the customary obligation of prevention (see Section III.B.1, above), the
positive obligations on a State to “protect” and “fulfill” human rights imposes “a due
diligence standard” on States,447 requiring diligent conduct in addressing the actual and
potential impact of climate change on the human rights of the population.
443 See, footnote 442, above.
444 Human Rights Committee, Billy et al. v. Australia, 21 July 2022, Individual opinion of Committee member
Gentian Zyberi (concurring), para. 3 (emphasis added).
445 IACHR Advisory Opinion, para. 180.
446 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
para. 7.2.10.
447 See, e.g., Human Rights Committee, Billy et al. v. Australia, 21 July 2022, para. 3.
111
366. Some courts have taken the position that States must respect the principle of prevention,
under customary law, in order to fulfil their human rights obligations in the context of
climate change.448 Other courts have examined whether a State has acted with
appropriate diligence in adopting climate change mitigation measures given the State’s
human rights or related fundamental rights obligations, without analysing this question
through the prism of the customary obligation of prevention.449 Irrespective of the
approach, courts have confirmed that, to respect their human rights obligations, States
must exercise due diligence in adopting and implementing effective mitigation
action.450
367. Domestic courts and human rights bodies in developed countries have already
condemned certain States for their failure to adopt effective mitigation action, thereby
violating their human rights and/or fundamental rights obligations.451 They did so both
with regard to insufficient mitigation action in the past; and insufficient mitigation
commitments for the future.
448 IACHR Advisory Opinion, para. 133, 141-174 (the obligation of prevention, entails a duty, among other, to (a)
regulate the activity, taking into account the existing level of risk, in a way that reduces any threat to the rights
of life and to personal integrity; (b) supervise and monitor the activity; (c) require and approve an EIA; (d)
prepare a contingency plan; and (e) mitigate if environmental damage occurs, based on the best available
scientific data and technology). See also, Ogoni, para. 52 (finding that to comply with the right to health and
to a healthy environment under Article 24 of the African Charter, States must “take reasonable and other
measures to prevent pollution and ecological degradation, to promote conservation, and to secure an
ecologically sustainable development and use of natural resources”); see also Constitutional Court of
Colombia, Center for Social Justice Studies et al. v. Presidency of the Republic et al., 10 November 2016
(available here, unofficial English translation available here), para. 7.34.
449 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
para. 5.7.1, stating that “it is in the opinion of the Supreme Court, that, under Articles 2 and 8 ECHR, the
Netherlands is obliged to do ‘its part’ in order to prevent dangerous climate change, even if it is a global
problem”); and Supreme Federal Court of Brazil, Vote of Minister Cármen Lúcia, PSB et al. v. Brazil, 6 April
2022 (available here), para. 8.
450 See, e.g., Human Rights Committee, Billy et al. v. Australia, 21 July 2022, para. 5 (“States should act with due
diligence based on the best science when taking mitigation … action.”).
451 See, e.g., Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January
2020; see also, Convention on the Rights of the Child, General comment No. 26, Children’s rights and the
environment, with a special focus on climate change, 22 August 2023, CRC/C/GC/26, para. 98; Human Rights
Committee, Billy et al. v. Australia, 21 July 2022, para. 8.3 (see also, Individual opinion of Committee member
Duncan Laki Muhumuza (dissenting), paras. 6-7); see also, German Constitutional Court, Neubauer et al. v.
Germany, 24 March 2021, paras. 183, 243 and 266; Brussels Court of Appeal, VZW Klimaatzaak v. Kingdom
of Belgium & Others, 30 November 2023, paras. 237-238; Korean National Human Rights Commission,
Opinion on the climate crisis and human rights, 2023 (unofficial English translation available here), p. 23; and
Administrative Court of Paris, Notre Affaire a Tous and Others v. France, 14 September 2021, pp. 31-32,
Article 2 (available here, unofficial English translation available here).
112
368. For example, the Dutch Supreme Court in the Urgenda case found that the Netherlands
had failed to adopt sufficiently deep emission reduction measures before the end of
2020.452
369. The German Constitutional Court in Neubauer et al. v. Germany found that Germany’s
climate laws governing national climate targets and the annual emission amounts
allowed until 2030 are incompatible with fundamental rights insofar as they lack
sufficient specifications for further emission reductions from 2031 onwards.453
370. South Korea’s National Human Rights Commission found that the Korean government
had failed to set sufficient mitigation reduction targets for 2030 and faulted the
government for not setting any mitigation target beyond 2030. The Commission
concluded that “considering the proportionality of the burden of GHG reduction for
current and future generations and the responsibility of Korea as a developed country,
the government should set additional GHG reduction targets.”454
371. Most recently, in Klimaatzaak v. Belgium, the Brussels Court of Appeal found that
Belgium violated its human rights obligations by failing to adopt sufficient mitigation
action.455 Looking backward, for the period 2013-2020, Belgium had failed to adopt
sufficiently deep emission reduction measures. Looking forward, for the period to
2030, to meet its human rights obligations, Belgium must take mitigation action to
reduce its emissions by 55 percent (compared to 1990 levels) by 2030.
452 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
para. 8.3.5.
453 Bundesverfassungsgericht, “Constitutional Complaints against the Federal Climate Change Act Partially
Successful,”, 29 April 2021 (available here); see also, German Constitutional Court, Neubauer et al. v.
Germany, 24 March 2021, p. 6.
454 See, National Human Rights Commission (Korea), Opinion on the climate crisis and human rights, 2023
(unofficial English translation available here), p. 23.
455 See, Brussels Court of Appeal, VZW Klimaatzaak v. Kingdom of Belgium & Others, 30 November 2023,
para. 237.
113
(2) To respect its human rights obligations, a State must adopt effective
mitigation measures on the basis of the best available science
372. The CESCR has explained that, to respect their human rights obligations, States must
set the level of ambition “on the basis of the best scientific evidence available”.456 In
the words of the Human Rights Committee member, Gentian Zyberi, in Billy et al. v.
Australia (2022), “States should act with due diligence based on the best science when
taking mitigation … action.”457
373. In this regard, the IPCC’s work “makes it clear that to avoid the risk of irreversible and
large-scale systemic impacts, urgent and decisive climate action is required”.458 The
most recent scientific evidence, including from the IPCC, underscores even more the
need for urgent and decisive mitigation action.459 As several UN human rights bodies
explained in a joint statement, “adverse impacts on human rights are already occurring
at 1°C of warming and every additional increase in temperatures will further undermine
the realization of rights.”460
374. It follows that, to assess whether mitigation action is sufficient to respect a State’s
human rights obligations, the mitigation action must be assessed in light of temperature
targets informed by the best, most recent science (such as the latest IPCC reports); and
not just by the temperature target set out in the Paris Agreement.
375. It follows that, at a minimum, the 1.5°C temperature target must now replace the 2.0°C
temperature target, when States define their mitigation action in a manner consistent
their human rights obligations.
376. Thus, in Klimaatzaak v. Belgium, the Brussels Court of Appeal explained that “le
rapport spécial du GIEC de 2018 a confirmé qu’il fallait dorénavant abandonner
456 UN Committee on Economic, Social and Cultural Rights, “Climate change and the International Covenant on
Economic, Social and Cultural Rights”, UN Doc. E/C.12/2018/1, 31 October 2018, para. 5. See also, Human
Rights Committee, Billy et al. v. Australia, 21 July 2022, para. 5.
457 See, e.g., Human Rights Committee, Billy et al. v. Australia, 21 July 2022, para. 5.
458 CEDAW, et al., Joint Statement on “Human Rights and Climate Change”, 16 September 2019 (available here),
emphasis added.
459 See, sub-section II.B.4, above.
460 CEDAW, et al., Joint Statement on “Human Rights and Climate Change”, 16 September 2019 (available here)
(emphasis added). See also, Brussels Court of Appeal, VZW Klimaatzaak v. Kingdom of Belgium & Others,
30 November 2023, para. 164.
114
l’objectif de 2°C pour celui de 1,5° C” (unofficial translation: “The IPCC’s 2018
Special Report confirmed that the 2°C target must now be replaced by the 1.5°C
target”).461
377. The Finnish Supreme Administrative Court likewise ruled that “[b]ased on the best
scientific evidence, climate change is a matter of human destiny, threatening the
livelihoods of current and future generations on Earth unless urgent and effective action
is taken to limit emissions and conserve and enhance carbon sinks. Therefore,
postponing action will shift responsibility to the future and make it more difficult to
achieve the 1.5°C maximum temperature increase target of the Paris Agreement.”462
(3) To respect its human rights obligations, a State must adopt effective
mitigation measures, based on fairness, equity and CBDR-RC
378. To respect its human rights obligations, a State cannot excuse its own mitigation
inaction on the basis that other States might not take sufficient emission reduction
action of their own; instead, each State must do “its part”.
379. The Dutch Supreme Court in the Urgenda case said that “every reduction means that
more room remains in the carbon budget”, and “no reduction is negligible”.463 The
German Constitutional Court Neubauer et al. v. Germany held that “[t]he fact that no
state can resolve the problems of climate change on its own due to the global nature of
the climate and global warming does not invalidate the national obligation to take
climate action.”464 The Brussels Court of Appeal in Klimaatzaak v. Belgium concurred
with this view.465
461 See, Brussels Court of Appeal, VZW Klimaatzaak v. Kingdom of Belgium & Others, 30 November 2023,
para. 30.
462 See, Finnish Supreme Administrative Court, Finnish Association for Nature Conservation and Greenpeace v.
Finland, 2023 (available here, unofficial English translation available here), p. 21, para. 66.
463 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
paras. 5.7.7 and 5.7.8.
464 German Constitutional Court, Neubauer et al. v. Germany, 24 March 2021; see also, Committee on the Rights
of the Child, Sacchi v. Argentina et al., 10 August 2021 para. 10.1
465 Brussels Court of Appeal, VZW Klimaatzaak v. Kingdom of Belgium & Others, 30 November 2023, para. 160.
115
380. The Dutch Supreme Court in the Urgenda case found that each State party to a human
rights treaty should do “its part” in order to prevent dangerous climate change.466
Referring to the principles of the UNFCCC, including fairness, equity and CBDR-RC,
the Court held that each State “has an obligation to take the necessary measures in
accordance with its specific responsibilities and possibilities.”467 Consistent with the
obligations under the climate change regime and customary international law, each
State must, therefore, determine “its part” – its equitable share – and this “part” is
differentiated in light of States’ different responsibilities and capabilities.468
381. Likewise, in Sacchi et al. v. Argentina, Brazil, France, Germany and Turkey (2021),
the Committee on the Rights of the Child held that “[i]n accordance with the principle
of common but differentiated responsibility, as reflected in the Paris Agreement, the
Committee finds that the collective nature of the causation of climate change does not
absolve the State party of its individual responsibility that may derive from the harm
that the emissions originating within its territory may cause to children, whatever their
location”.469
382. In finding that the Korean government must set more ambitious mitigation targets, the
South Korea’s National Human Rights Commission also took into account “the
responsibility of Korea as a developed country”.470
383. Finally, in Billy et al. v. Australia (2022), the Human Rights Committee member,
Gentian Zyberi, explained in a concurring opinion that:
States should act with due diligence when taking mitigation and
adaptation action, based on the best science. This is an individual
responsibility of the State, relative to the risk at stake and its
capacity to address it. A higher standard of due diligence
466 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
paras. 5.7.1-5.7.9 (emphasis added).
467 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
para. 5.7.3.
468 Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January 2020,
para. 5.7.5; see also, National Human Rights Commission (Korea), Opinion on the climate crisis and human
rights, 2023, p. 9 (unofficial English translation available here).
469 See also, Committee on the Rights of the Child, Sacchi v. Argentina et al., 10 August 2021, para. 10.10
(emphasis added).
470 See, National Human Rights Commission (Korea), Opinion on the climate crisis and human rights, 2023, p. 23
(unofficial English translation available here).
116
applies in respect of those States with significant total emissions
or very high per capita emissions (whether these are past or
current emissions), given the greater burden that their emissions
place on the global climate system, as well to States with higher
capacities to take high ambitious mitigation action.471
384. The Committee Member found that “[t]his higher standard applies to the State party in
this case [i.e., Australia]”.472
d. Obligations arising under the UNCLOS
385. Article 192 of the UNCLOS provides, generally, that “States have the obligation to
protect and preserve the marine environment”.473 Article 194 more specifically
provides:
States shall take, individually or jointly as appropriate, all
measures consistent with this Convention that are necessary to
prevent, reduce and control pollution of the marine environment
from any source, using for this purpose the best practical means
at their disposal and in accordance with their capabilities, and
they shall endeavour to harmonize their policies in this
connection.474
386. These terms establish a due diligence obligation on States to do their utmost, using all
the means at their disposal, to reduce emissions sufficient to keep long-term
temperatures at a level that would prevent, reduce and control pollution of the marine
environment.
i. Anthropogenic GHG emissions constitute pollution of
the marine environment
387. The first issue under Article 194 of the UNCLOS is whether anthropogenic emissions
involve “pollution of the marine environment”, which is defined in Article 1(4) of the
UNCLOS as:
… the introduction by man, directly or indirectly, of substances
or energy into the marine environment, including estuaries,
which results or is likely to result in such deleterious effects as
harm to living resources and marine life, hazards to human
471 Human Rights Committee, Billy et al. v. Australia, 2022, para. 5 (emphasis added).
472 Human Rights Committee, Billy et al. v. Australia, 2022, para. 5.
473 See generally, Responsibilities in the Area.
474 Emphasis added.
117
health, hindrance to marine activities, including fishing and other
legitimate uses of the sea, impairment of quality for use of sea
water and reduction of amenities.
388. As Antigua and Barbuda has explained in Section 0 above, anthropogenic GHG
emissions cause both carbon dioxide and heat to be absorbed into the ocean, with
extensive harmful effects.475 Under the definition in Article 1(4), therefore,
anthropogenic GHG emissions are a source of pollution of the marine environment.
389. Specifically, the term “substances or energy” covers both carbon dioxide (a
“substance”) and heat (thermal “energy”).476 When carbon dioxide and heat from
anthropogenic emissions are absorbed into the ocean, they are “introduc[ed]” “directly
or indirectly” into the marine environment by man.477 They result in extensive
“deleterious effects”. The absorption of carbon dioxide results in ocean acidification;478
the absorption of heat results in higher ocean temperatures and sea level rise.479 In each
instance, these cause, at minimum, “harm to living resources and marine life”, “hazards
to human health” and “hindrance to marine activities”.480
390. Indeed, the environmental impacts of anthropogenic GHG emissions are felt acutely by
the oceans. The oceans play a key role in the Earths’ climate system, and two key
drivers of harm from climate change – sea level rise and ocean acidification – have a
special impact on marine habitats and ecosystems, and on related human activities like
fishing and coastal infrastructure.
391. In this respect, the UNCLOS is the primary international legal regime which deals
specifically with obligations relating to pollution of the marine environment and its
consequential harms.
475 See, Section II, above.
476 See, Oxford English Dictionary, “substance, n.” (available here); see also, Oxford English Dictionary, “energy,
n.” (available here).
477 See, sub-section II.C.1.
478 See, sub-section II.C.1.
479 See, sub-section II.C.1.
480 See, sub-section II.C.2 and II.C.3; see also, UNCLOS, Article 193(a).
118
ii. States must reduce GHG emissions, to the fullest extent
possible, as soon as possible, in order to prevent, reduce
and control marine pollution
392. Article 194 requires States to adopt measures necessary to “prevent, reduce and control”
pollution to the marine environment.
393. The three verbs in Article 194 – prevent, reduce, control – each have their own meaning,
and apply cumulatively. The verb “prevent” means to stop or hinder marine pollution;
the verb “reduce” means to diminish or lower those pollution levels; and the verb
“control” means to manage the pollution.481
394. An UNCLOS Party cannot choose to comply with the least demanding of these three
verbs, namely, taking measures to “control” marine pollution. Yet, under the Paris
Agreement, States have agreed to do just this. The Paris Agreement calls for States to
pursue efforts to limit warming to 1.5°C.482 The agreement to achieve this temperature
goal foresees considerable continued emissions, albeit at a lower rate, which will lead
to considerably increased marine pollution. Under the Paris Agreement, States have,
therefore, sought to “control” marine pollution, but not to “reduce” its accumulated
levels in the ocean or “prevent” further pollution.
395. Article 194(1) requires States to go further, pursuing effective emission reduction
measures that will “prevent” marine pollution from occurring and will “reduce” the
accumulated levels of marine pollution.
396. As noted above, Article 194(1) establishes a “due diligence” obligation, meaning States
do not face strict liability for their failure to “prevent” and “reduce” marine pollution.
However, States are responsible for taking all available means at their disposal to
achieve these outcomes. The obligation in Article 194(1) cannot be satisfied simply
with a degree of “control” over pollution.
397. In that regard, Article 194(1) obliges States to adopt the measures “necessary” to
prevent, reduce and control marine pollution. With respect to climate change, the
necessary measures are well known: they involve rapid, deep and sustained emission
481 See, Oxford English Dictionary, “prevent, v.” (available here); Oxford English Dictionary, “reduce, v.”
(available here); and Oxford English Dictionary, “control, v.” (available here).
482 Paris Agreement, Article 2.1(a).
119
reductions. As set forth above, the IPCC has evaluated the available measures to
achieve such reductions, including their efficacy in terms of both cost and emission
reductions.483 States must, therefore, do their utmost to adopt and enforce these
measures, with a view to preventing marine pollution.
398. Other provisions of the UNCLOS add further content to the character of the due
diligence obligations under Article 194(1), specifying the types of measures that States
must adopt. In the specific case of pollution from land-based sources, Article 207(1)
and (2) provides that States “shall adopt laws and regulations” to prevent, reduce and
control such pollution, as well as “other measures as may be necessary”. Under
Article 213, States “shall enforce” such laws and regulations in order to prevent, reduce
and control marine pollution from land-based sources.
399. Under Article 207(5), States must adopt laws, regulations, measures and other legal
instruments “designed to minimize, to the fullest extent possible, the release of” harmful
substances from land-based sources, “especially those which are persistent”.484
400. This provision confirms a central aspect of Antigua and Barbuda’s arguments: States
cannot choose to comply with the least demanding of the three verbs in Article 194(1),
by taking measures that merely seek to “control” marine pollution. Rather, at all times,
they must deploy measures to “minimize” the release of persistently harmful
substances, which includes GHG emissions. The verb “minimize” means that GHG
emissions must be reduced to their smallest possible quantity. The text of
Article 207(4) also uses the superlative “fullest” to underscore the considerable extent
of this obligation to minimise the release of persistently harmful substances.
401. As with the customary obligation of prevention and the Paris Agreement, the due
diligence obligation in Article 194(1) is differentiated between and among the
UNCLOS Parties, consistent with the principle of fairness, equity and CBDR-RC that
applies in the context of climate change. This is because Parties must act using “the
best practicable means at their disposal and in accordance with their capabilities”.
These terms recognise that the conduct required to act with diligence depends on what
is practically available, and within the capabilities of a State. This phrase means that
483 See, sub-section II.D.2, above.
484 UNCLOS, Article 207.5 (emphasis added).
120
the obligation in Article 194(1) applies asymmetrically: States with the greater “means”
and “capabilities” – i.e., developed States – bear the heavier burden.
402. Finally, Article 197 provides that “States shall cooperate on a global basis”, echoing
and developing the customary international law obligation of cooperation. Specifically,
they must cooperate in “formulating and elaborating international rules, standards and
recommended practices and procedures consistent with this Convention”, including as
required in parallel under Article 207(4).
403. As explained above, the duty to cooperate bears particular weight in the context of
climate change, since acting with due diligence requires States to divide equitably the
available carbon budget amongst themselves. States must cooperate to ensure that the
collective level of emissions reductions is sufficient to ensure that continued emissions
by States, as equitably divided among them, stay within the available carbon budget.
e. Obligations arising under the international trade law regime
404. As addressed above, States are under an obligation to deploy all the means at their
disposal to achieve rapid, deep and sustained GHG emissions reductions sufficient to
prevent activities within their jurisdiction or control causing significant environmental
harm, in a manner consistent with the principles of fairness, equity and CBDR-RC. In
doing so, States are granted discretion, with certain boundaries, as to the specific
mitigation measures they pursue. Such measures may include, among others: border
charges and restrictions, internal taxes, regulations, production standards and subsidies.
405. These unilateral trade-related measures raise concerns because one State may seek to
use its own import policies to reduce emissions in a developing State, even though the
Paris Agreement would allow the developing State to decide its own nationally
determined contribution to reducing emissions, in light of its common but differentiated
responsibilities and respective capabilities, considered in the light of its own national
circumstances. At the same time, such unilateral measures can also prejudice the
development interests of developing exporting States, with consequential effects on
social development and even on the resources available to tackle climate change.
406. These unilateral trade-related climate measures are legal hybrids: they implicate areas
of international law relating to the environment generally, and to climate specifically –
121
as addressed above – and they also implicate international law related to trade, most
notably under the WTO covered agreements.485
407. In considering such measures, it is appropriate to take account of all relevant parts of
international law. The WTO Appellate Body considers that WTO law “is not to be read
in clinical isolation from public international law”.486 This position is consistent with
the presumption in international law that different parts of international law should, as
far as possible, be interpreted and applied in a coherent and consistent manner.487 In
the words of the ILC, “[i]t is a generally accepted principle that when several norms
bear on a single issue they should, to the extent possible, be interpreted so as to give
rise to a single set of compatible obligations.”488 This principle of systemic integration
avoids fragmentation, and gives full effect to all relevant aspects of international law,
in a coherent and effective manner.
408. At the most recent WTO Ministerial Conference (Abu Dhabi, February 2024), a large
group of developing WTO Members echoed the need to take into account all relevant
parts of international law. In a Ministerial Declaration, this group of countries noted
that:
WTO law is not to be read in clinical isolation from public
international law. Trade-related environmental measures and
policies, due to their hybrid nature, must simultaneously respond
to a multiple set of principles and parameters recognized by
international environmental law and international trade law,
including equity and Common but Differentiated
Responsibilities and Respective Capabilities.489
485 See, TESS Expert Report, Principles of International Law Relevant for Consideration in the Design and
Implementation of Trade-Related Climate Measures and Policies, September 2023 (available here).
486 WTO Appellate Body Report, US – Gasoline, p. 17.
487 See, TESS Expert Report, Principles of International Law Relevant for Consideration in the Design and
Implementation of Trade-Related Climate Measures and Policies, September 2023 (available here).
488 ILC, Report on Fragmentation of International Law, p. 8. See, footnote 354, above.
489 “Ministerial Declaration on the Contribution of the Multilateral Trading System to Tackle Environmental
Challenges”, Communication from Argentina, Bangladesh, Barbados, Plurilateral State of Bolivia, Brazil,
Cabo Verde, Colombia, Ecuador, Egypt, Honduras, Indonesia, Kazakhstan, Panama, Paraguay, Peru, South
Africa, Uruguay, Bolivarian Republic of Venezuela, and the African Group, (WT/MIN(24)/28), 29 February
2024, para. 10 (available here).
122
409. This group of countries, further, “[e]mphasize[d] that it is only through mutual
supportiveness and harmonized application of international instruments such as MEAs
and WTO Agreements that sustainable development can be meaningfully achieved”.490
410. With respect to the international trade law bearing on unilateral trade-related climate
measures, a State’s measures must, in principle, respect that State’s obligations under
the WTO covered agreements. They must, for example, not discriminate on the basis
of origin; entail customs duties or charges in excess of permissible levels; or amount to
a quantitative restriction.491
411. However, if a trade-related climate measure violates a WTO obligation, the State may
be entitled to invoke an exception under the WTO agreements. For example,
Article XX of the GATT 1994 sets forth a general exception that may justify measures
that violate the GATT 1994, because the measure pursues some non-trade interest (like
climate change mitigation).492
412. To enjoy an exception, a measure must meet the legal conditions set out in the
exception. In past WTO cases, these conditions have been applied to ensure that other
parts of international law bearing on a measure are taken into account in assessing
whether a measure that violates WTO obligations is justified by a non-trade interest.493
In other words, the conditions have served to ensure coherence and consistency within
public international law, avoiding fragmentation and the clinical isolation of WTO law.
413. First, a measure must pursue one of the closed list of “legitimate” non-trade objectives
enumerated in the paragraphs of Article XX of the GATT 1994. With respect to climate
change, two of the paragraphs are most relevant: paragraph (b) (covering measures
“necessary for the protection of human, animal or plant life or health”); and paragraph
(g) (covering measures “related to the conservation of exhaustible natural resources”).
490 See, footnote 489, above.
491 See, Article I of the GATT 1994 (most favoured nation principle); Article II of the GATT 1994 (customs
duties or charges in excess) and Article XI of the GATT 1994 (quantitative restrictions).
492 Certain other WTO covered agreements have equivalent “exception” provisions, e.g., Article XIV of the
General Agreement on Trade in Services.
493 See, footnote 496, below.
123
414. Second, a measure must satisfy the conditions in the chapeau to Article XX: it may not
constitute a means of “arbitrary or unjustifiable discrimination”, or a “disguised
restriction on international trade”. These same terms appear in a number of multilateral
environmental treaties, including Article 3.5 of the UNFCCC (“measures taken to
combat climate change, including unilateral ones, should not constitute a means of
arbitrary or unjustifiable discrimination or a disguised restriction on international
trade”).494 The use of these terms across international law relating to trade and the
environment, including climate change, indicates a desire for coherence and
consistency.
415. The terms “arbitrary or unjustifiable discrimination” and “disguised restriction on
trade” relate to how a measure is applied in practice, calling for consideration of a broad
range of factors related to the measure’s application.495 These factors may include
provisions from binding or non-binding international legal instruments, beyond
international trade.496
416. With respect to a trade-related climate measure, Antigua and Barbuda highlights two
factors that are relevant in assessing whether the measure entails arbitrary or
unjustifiable discrimination or a disguised restriction on trade.
417. The first factor is that States must seek a cooperative solution, treating other States as
sovereign equals, before resorting to unilateral trade-restrictive climate measures. This
well-established requirement to pursue meaningful international cooperation flows
from the good faith character of the exception. In the case of climate change,
494 Similarly, Principle 12 of the Rio Convention states that “Trade policy measures for environmental purposes
should not constitute a means of arbitrary or unjustifiable discrimination or a disguised restriction on
international trade.”
495 Appellate Body Report, EC – Seals, para. 5.302
496 In US - Shrimp, for example, the Appellate Body took into account provisions of treaties, and several soft law
instruments of international environmental law, including Principle 12 of the Rio Declaration and Agenda 21.
Appellate Body Report, US - Shrimp, paras. 168 and 169. See also, Appellate Body Report, US - Shrimp (Art.
21.5), para. 124. In EC - Seals, in interpreting Article 2.1 of the TBT (where some of the analysis was
considered to apply to Article XX of the GATT as well), the panel also referred to other international law
instruments such as the UN Declaration on the Rights of Indigenous Peoples, the UN GA Resolution 61/295
(2007), ILO Convention 169, and the Charter of the Inuit Circumpolar Council.
124
cooperation is also a practical necessity to resolve an inherently transboundary
problem.497
418. As the WTO Appellate Body explained, “the need for, and the appropriateness” of
“concerted and cooperative efforts has been recognized in the WTO itself as well as in
a significant number of other international instruments and declarations”.498 The
Appellate Body referred to Principle 12 of the Rio Declaration, which states that
“[u]nilateral actions to deal with environmental challenges outside the jurisdiction of
the importing country should be avoided. Environmental measures addressing
transboundary or global environmental problems should, as far as possible, be based on
international consensus.”499
419. When “serious, good faith efforts” at international cooperation are unsuccessful, and
States take a unilateral measure, they cannot abandon efforts to find cooperative
solutions. Rather, they must continue to engage in “ongoing serious, good faith efforts”
to seek an agreed international solution.500
420. These requirements for continued cooperation are important to protect the integrity of
other international processes that seek to address climate change, in particular under the
UNFCCC and the Paris Agreement. If restrictive import policies could be used by a
developed country to force climate action on developing countries, developed countries
would have less incentive ether to work through the multilateral UNFCCC/Paris
Agreement processes or to fulfil their commitments to assist developing countries in
tackling climate change through financial support.
421. The second factor is the relationship between the unilateral trade-related climate
measure and the international climate change regime. When a State’s unilateral traderelated
climate measure tackles climate change in a manner inconsistent with the
497 Pulp Mills, p. 51, para. 81 (“[t]hese obligations are all the more vital when a shared resource is at issue, as
in the case of the River Uruguay, which can only be protected through close and continuous co-operation
between the riparian States”), p. 67, para. 145 (“[t]he Court notes, moreover, that the 1975 Statute is perfectly
in keeping with the requirements of international law on the subject, since the mechanism for co-operation
between States is governed by the principle of good faith”) and see also p. 49, para. 77. See also, Paris
Agreement, Articles 7.6, 8.3, 8.4, 10.2, 10.6, 11.3 and 14.3; UNFCCC, ninth preambular paragraph,
Articles 7.2(l) and 9.2(d); UNCLOS, Article 197; Rio Declaration, Principle 19 (regarding timely notification).
498 Appellate Body Report, US – Shrimp, para. 168.
499 Appellate Body Report, US – Shrimp, para. 168 (emphasis in the original).
500 Panel Report, US – Shrimp (Article 21.5), para. 6.1.
125
international climate change regime, it is a strong indicator that the measure entails
arbitrary or unjustifiable discrimination or a disguised restriction on trade.
422. One of the “most important factors” to assess whether a measure entails arbitrary or
unjustifiable discrimination is whether the discrimination “can be reconciled with, or is
rationally related to, the policy objective”.501 If a measure is inconsistent with the
international climate change regime, the measure’s trade-restrictive impact cannot be
“reconciled with” the climate objective. A State’s decision to adopt trade restrictions
without following the approach agreed in the international climate change regime
compromises the State’s climate-based justification. Indeed, such a unilateral measure
would upset the balance struck in the international climate change regime, and thereby
undermine that regime.
423. A prominent and important example of the potential tension between unilateral traderelated
climate measures and the international climate change regime concerns the
principle of fairness, equity and CBDR-RC. As set forth above, the parties to the
UNFCCC have agreed that this principle “shall” “guide …” “their actions to achieve
the objective of the Convention and to implement its provisions”; and the parties to the
Paris Agreement have agreed that “this Agreement will be implemented to reflect
equity and [CBDR-RC]”.502
424. The inclusion of this principle is fundamental to the architecture and balance of the
international climate change regime.503 In the context of climate change action, the
principle is also respected in other areas of international law, notably international
human rights law.
501 Appellate Body Report, EC – Seal Products, para. 5.306.
502 Article 3 of the UNFCCC; and Article 2.3 of the Paris Agreement; see also, UNFCCC, sixth preambular recital
and Article 4; Paris Agreement, Articles 3, 4.1, 4.3, 4.4, and 4.5; and C. Voigt and F. Ferreira, “Differentiation
in the Paris Agreement”, 5(1-2) Climate Law (2016), pp. 58-74.
503 See, e.g., L. Rajamani, ‘The principle of common but differentiated responsibilities and respective capabilities
in the international climate change regime,’ in R. Lyster and R. Verchick (eds), Research Handbook on
Climate Disaster Law: Barriers and Opportunities (Edward Elgar, 2018), p. 49 (CBDR-RC is “deeply
embedded in the climate regime” and “a fundamental part of the conceptual apparatus of the climate change
regime such that it forms the basis for the interpretation of existing obligations and the elaboration of future
international legal obligations within the climate change regime”); Philippe Cullet, “Differentiation” in L.
Rajamani, J. Peel (eds.), The Oxford Handbook of International Environmental Law, 2nd edn. (Oxford
University Press, 2021), p. 319; E. Hey and S. Paulini, “Common but Differentiated Responsibilities”, in Max
Planck Encyclopaedias of International Law, online edn., (Oxford University Press, 2021), para. 5.
126
425. In WTO law, the question whether a trade-related climate measure respects the
principle of fairness, equity and CBDR-RC should be a relevant factor, as part of the
assessment of arbitrary or unjustifiable discrimination.504 It is well accepted under the
chapeau of Article XX that arbitrary discrimination arises when an importing country
fails to take into relevant differences in the situation of producing countries. In
particular, an importing country must assess “the appropriateness of [a] regulatory
program for the conditions prevailing in those exporting third countries”.505
426. In that regard, the principle of fairness, equity and CBDR-RC recognises and addresses
the fact that very different conditions prevail in developing countries, compared with
developed countries, with respect to their responsibilities for climate change and their
capabilities for tackling it. Indeed, as outlined above, through the principle of fairness,
equity and CBDR-RC, the Paris Agreement expressly foresees that developed countries
will take more ambitious climate action in light of their greater responsibilities and
capabilities.
427. A unilateral trade-related climate measure that fails to account for the principle of
fairness, equity and CBDR-RC agreed in the international climate change regime – and
the fundamental differences the principle recognises and addresses – is a factor that
indicates discrimination against developing countries that is both arbitrary and
unjustifiable.
428. There is, in short, no justifiable basis for developed countries to violate their WTO
obligations through measures with the stated objective to tackle climate change, when
they do so in disregard for a fundamental feature of the agreed international climate
change regime.
504 See, TESS Expert Report, Principles of International Law Relevant for Consideration in the Design and
Implementation of Trade-Related Climate Measures and Policies, September 2023 (available here).
505 Appellate Body Report, US – Shrimp, paras. 164-165.
127
2. Obligations related to adaptation
a. Introduction: The need for, and limitations of, adaptation
measures
429. In this Section, Antigua and Barbuda turns to obligations relating to adaptation to
climate change. i.e., “the process of adjustment to actual or expected climate change
and its effects.”506
430. As discussed in Section III.C.1 above, States are under an obligation to undertake rapid,
deep and sustained reductions in GHG emissions to mitigate climate change, in a
manner consistent with the principle of fairness, equity and CBDR-RC. However,
GHG emissions have already led to an increase of, on average, between 1.1° C – 1.35°C
post-industrial levels, which, in turn, has led to a series of adverse events and
phenomena that are unfolding around the globe. These events and phenomena will
keep occurring – indeed worsen – as GHG emissions continue, and atmospheric
temperatures continue to rise.
431. Adaptation measures are how the world will minimise the harms of global warming
that has occurred and continues to occur. Specifically, adaptation measures entail
adjustments to human systems as well as to natural systems to ensure their resilience
and survival in the face of climate change.507 Adaptation actions include policy and
social changes, as well as physical modification of the environment and construction of
new infrastructure.
432. All States need to adopt adaptation measures, including and especially those States like
Antigua and Barbuda that have virtually zero responsibility for causing climate change.
In fact, despite having virtually zero responsibility, for SIDS, like Antigua and Barbuda,
the urgency of adaptation is extremely acute.508 These States have a unique
vulnerability to climate change impacts due to their size and geographical location.509
506 IPCC, Fifth Assessment Report, 2014, Synthesis Report (Working Groups I, II and III), Glossary (available
here), p. 118 (emphasis added).
507 Paris Agreement, Article 7.2.
508 On the urgency of adaptation, see, UNFCCC COP, Decision 1/CMA.3, “Glasgow Climate Pact” (2021)
(available here), para. 6.
509 See, sub-sections II.C.2 and II.C.3, above.
128
To give just one example, for Antigua and Barbuda, the impacts of climate change
threaten economic activities that generate 80.4 percent of the country’s GDP.510
433. Antigua and Barbuda has, therefore, been proactive in identifying, planning and
implementing the adaptation actions which are within its own capabilities; and has been
proactive in calling on other States to meet their obligations under international law to
support adaptation actions in Antigua and Barbuda.
434. Antigua and Barbuda already identified critical adaptation needs in its first NDC of
2015,511 and the list expanded further in its 2021 NDC update.512 These activities range
from increasing the capacity and resilience of threatened water supplies; protecting
waterways from flooding; to a swathe of measures to respond to increased extreme
weather events, including improving building standards to better withstand stronger and
more frequent hurricanes and other infrastructure, improving access to and use of offgrid
and back-up renewable energy sources; and building resilient emergency shelter
facilities.
435. The indicative cost of implementing Antigua and Barbuda’s mitigation and adaptation
targets through to 2030 is estimated at between USD 1-1.7 billion, which represents
between 65 percent and 110 percent of the country’s GDP in 2021.513 And beyond
2030, the adaptation costs are even expected to increase significantly over time.514
436. Evidently, a small and vulnerable developing economy like that of Antigua and
Barbuda, which has contributed just 0.001 percent to the historic cumulative emissions,
is not economically able to shoulder this responsibility alone and nor is it legally
expected to do so. To this end, a key theme running through international adaptation
510 Antigua and Barbuda, “Updated Nationally Determined Contribution for the period 2020-2030” (2021)
(available here), p. 27.
511 Antigua and Barbuda, “Intended Nationally Determined Contribution” (2015) (available here).
512 Antigua and Barbuda, “Updated Nationally Determined Contribution for the period 2020-2030” (2021)
(available here); Antigua and Barbuda, “Adaptation Communication: Antigua and Barbuda’s submission to
the UNFCCC” (2022) (available here), pp. 40-43.
513 Antigua and Barbuda, “Updated Nationally Determined Contribution for the period 2020-2030” (2021)
(available here), p. 23.
514 See, footnote 513, above.
129
obligations is the need for adequate financing, especially for those SIDS with the most
acute adaptation costs ahead of them.
437. Finally, adaptation measures are central to the objective of the UNFCCC, namely the
prevention of dangerous anthropogenic interference with the climate system to enable
adaptation to climate change. Yet, it is also crucial to recognise the inherent limits of
adaptation measures. As a result of States’ historical emissions, warming is already
occurring at a pace and scale that cannot be entirely addressed through adaptation
measures, leading inevitably to concrete harms (i.e., “loss and damage”).515 Indeed, as
Antigua and Barbuda has emphasised throughout this Written Statement, it has already
suffered loss and damage as a result of climate change. This must be taken into account
when considering factors – addressed below – such as what quantity of support
(financial and other) is necessary to support States’, especially developing States,
individual responses to the climate crisis. Responsibilities arising from loss and
damage that has already occurred is further addressed Section 0 of this Written
Statement (i.e., the second question posed to the Court).
438. Below, Antigua and Barbuda discusses, in turn, the adaptation obligations under the
international climate change regime (sub-section (b)), and the UNCLOS (sub-section
(b)).
b. Adaptation obligations under the international climate change
regime
439. The international climate regime, particularly the Paris Agreement, sets out certain
obligations for States in respect of adaptation. In this Section, Antigua and Barbuda
focuses on the adaptation obligation arising under Article 7.9. The obligation on States
to provide support to developing country Parties for adaptation measures, under
Article 7.13, is discussed in sub-section III.B.3, below.
440. Article 7.9 of the Paris Agreement provides as follows:
Each Party shall, as appropriate, engage in adaptation planning
processes and the implementation of actions, including the
development or enhancement of relevant plans, policies and/or
contributions, which may include:
515 See, sub-section II.C, para. 49, above.
130
(a) The implementation of adaptation actions,
undertakings and/or efforts;
(b) The process to formulate and implement national
adaptation plans;
(c) The assessment of climate change impacts and
vulnerability, with a view to formulating nationally
determined prioritized actions, taking into account
vulnerable people, places and ecosystems;
(d) Monitoring and evaluating and learning from
adaptation plans, policies, programmes and actions; and
(e) Building the resilience of socioeconomic and
ecological systems, including through economic
diversification and sustainable management of natural
resources.
441. These terms establish an obligation (“shall”) to “engage in adaptation planning
processes”, and to implement “[adaptation] actions”. However, unlike the mitigation
obligation under Article 4.2, the adaption obligation under Article 7.9 is qualified by
the terms “as appropriate”. This is a critical difference between the mitigation
obligation under Article 4.2, and the adaptation obligation under Article 7.9.
442. Based on the ordinary meaning of the term “as appropriate”, States’ obligation to take
adaptation measures is contingent on what is suitable or proper for the circumstances.
Thus, States are granted considerable discretion in how they go about their adaptation
planning, and in the implementation of adaptation actions. Subparagraphs (a) through
(e) of Article 7.9 provide a non-exhaustive list of how States may go about iteratively
planning and implementing their adaptation actions. Under each step, it is for each
State to identify its own adaptation needs, make plans to meet those needs, and
implement the necessary measures.
443. The term “as appropriate” must be understood in light of the context to Article 7(9).
444. First, the term “as appropriate” qualifies the required adaptation actions in light of each
Party’s capacities; consistent with Article 2.2, which provides that the Agreement –
including Article 7 – will be implemented to reflect equity and the principle of fairness,
equity and CBDR-RC. The need to take into account each Parties’ capacities is,
specifically, reflected in Article 7.6, which recognises the “importance of support for
and international cooperation on adaptation efforts”, and of “taking into account the
131
needs of developing country Parties, especially those that a particularly vulnerable to
the adverse effects of climate change”.
445. For developing countries with high adaptation needs, like SIDS, the obligation is
especially qualified by the receipt of adequate support for planning and implementing
adaptation measures, per the terms of Article 7.13. Indeed, as explained below,
Article 7.13 requires “continuous and enhanced international support” for developing
Parties to implement, among others, paragraph 9. Unlike Article 7.9, the obligation to
provide support under 7.13 is not qualified by the term “as appropriate”.
446. Second, the adaptation obligation under Article 7.9 must also be understood, and
implemented, in light of the global adaptation goal, in Article 2.1(b) and, expressed in
more detail, in Article 7.1. Article 2.1(b) recognises that the Agreement aims to
“strengthen the global response to climate change” by “enhancing adaptive capacity,
strengthening resilience and reducing vulnerability to climate change”. Article 7.1
more specifically establishes this goal “with a view to contributing to sustainable
development and ensuring an adequate adaptation response in the context of the
temperature goal referred to in Article 2”.
447. Pursuit of this global goal means that, in making individual adaptation plans and
implementing them, States should be mindful of the interrelationships between
different countries’ adaptation efforts. States should, therefore, pursue their national
adaptation measures in a cooperative manner, helping to ensure their adaptation actions
achieve maximum effectiveness and efficiency.
c. Adaptation obligations under the UNCLOS
448. In this sub-section, Antigua and Barbuda first explains that Article 192 of the UNCLOS
imposes a due diligence obligation on the Parties in respect of adaptation. Thereafter,
Antigua and Barbuda explains that Article 192, read with Article 197, requires an
asymmetric allocation of the burden of adaptation.
i. Article 192 imposes a due diligence obligation in respect
of adaptation
449. Article 192 of the UNCLOS requires States parties to “protect and preserve the marine
environment”. As discussed above, this obligation requires States to safeguard the
132
marine environment from future harm, and to maintain or improve the present condition
of the marine environment.516
450. As explained above, the obligation under Article 192 is one of due diligence, requiring
States to do their utmost, using all the means at their disposal for this purpose.517 To
recall, as explained above, in the context of Article 194, “due diligence” is a “variable
concept”.518 The variables determining the level of diligence “due” in a particular
circumstance include:
• The level of threat to the marine environment: As the Seabed Disputes Chamber
clarified, “[t]he standard of due diligence has to be more severe for the riskier
activities”.519 That is, in dealing with circumstances entailing higher risks to the
marine environment, a higher level of diligence is due.
• The level of knowledge of the risk: The level of diligence required varies as the
body of available knowledge regarding a particular risk evolves. Additional
knowledge about the level of risk or additional risk factors may result in the need
to re-calibrate the level of diligence.
• The level of available technological knowledge: As technology evolves, States may
have more solutions to a problem available to them, and may come under an
obligation to deploy those means.
• Availability of means to address the risk: A due diligence obligation, requires States
to do their “utmost” and deploy “all the means at [their] disposal” in its pursuit.
Thus, the level of diligence varies with the extent of the means available to a State.
The more means a State has at its disposal, the more demanding is the conduct
required of it to meet the due diligence obligation.
451. In the case of climate change, a high level of diligence is required, since: (i) the risk
involved is very high, possibly existential; (ii) the level of knowledge about the risk is
very high, given extensive scientific knowledge about climate change and its effects;
and (iii) the means to protect the marine environment from this threat are well-known.
As such, States must deploy a high level of diligence.
452. As explained above, the adoption of adaptation measures are necessary to minimise
harms to the environment (including the marine environment) resulting from global
516 South China Sea Arbitration, para. 941.
517 See, paras. 385-403, above.
518 See, Responsibilities in the Area, p. 43, para. 117.
519 See, Responsibilities in the Area, p. 43, para. 117.
133
warming. Without adequate adaptation measures, environmental harm from global
warming is more severe. The due diligence obligation in Article 192 to “protect and
preserve” the marine environment therefore encompasses an obligation on States to do
the utmost, and use all means at their disposal, to take appropriate adaptation measures.
453. Importantly, this obligation is qualified according to what is appropriate for each
individual State, depending on its capacity to take such adaptation measures, consistent
with the principle of CBDR-RC as expressed in the international climate regime, and
incorporated into Article 192 of the UNCLOS (as discussed further below). For
developing States, this also includes what is appropriate in light of the adequacy of
support provided by developed States for developing States’ adaptation efforts.
454. The due diligence nature of the obligation under Article 192 has important
consequences for the allocation of shared burdens under the obligation, as Antigua and
Barbuda will explain below in Section IV. As discussed in the following sub-section,
States with more extensive means at their disposal are required to carry a larger share
of the burden of obligations than States with more limited means.
ii. The asymmetric nature of the obligation under
Article 192, in respect of adaptation
455. The obligations under Article 192 are differentiated and asymmetric. That is,
developed States must carry a larger share of the obligations imposed by Article 192,
including by supporting adaptation actions in the territories of developing countries.
456. To recall, the general obligation in Article 192, to “protect and preserve the marine
environment” is further elaborated in other provisions in Part XII of the UNCLOS.
Among them is Article 197, which requires States parties to cooperate in the
formulation of “international rules” and “standards” for the protection and preservation
of the marine environment. Article 197 also requires States to abide by such
international rules once they are formulated, lest the cooperative formulation of rules
pursuant to Article 197 be rendered futile.
457. The international climate change regime represents such “international rules” and
“standards”, which have been formulated cooperatively. Thus, UNCLOS parties are
obliged by Article 197 to abide by their commitments in the international climate
change regime.
134
458. One of the key rules of the international climate change regime is the principle of
fairness, equity and CBDR-RC, which is reflected in the text of the UNFCCC and the
Paris Agreement. Based on this principle, among others, developed States have
undertaken commitments within the international climate change regime to provide
financing, technology, and capacity building assistance to the adaptation efforts of
developing States. Articles 192 and 197 require developed States to make good on
these commitments.
459. As such, the financing and support obligations in the international climate change
regime, discussed above, in so far as they relate to adaptation measures concerning the
marine environment, are incorporated as UNCLOS obligations through the operation
of Article 197.
460. Indeed, the cost of adaptation faced by developing countries is such that they simply
cannot implement the necessary adaptation measures unless developed countries
deliver on their financing and support commitments – a point recognised in Articles 7.7
and 7.13 of the Paris Agreement. Given the due diligence nature of the obligation in
Article 192, the obligation of the developing States to implement adaptation measures
is a function of the “means” available to them. It is the fulfilment of the financing and
support commitments by the developed States that will make the necessary means
available to developing countries; in this sense, the obligation of developing countries
to implement adaptation measures within their territory is contingent.
461. In sum, the UNCLOS creates the following specific obligations for States in respect of
adaptation actions relating to the marine environment:
• All States are under an obligation to identify adaptation needs in their territories,
prepare adaptation plans, and implement adaptation plans. For developing
countries, this obligation is contingent on the receipt of support in line with the
obligations listed below.
• All States are under an obligation to prepare and implement adaptation plans in a
cooperative manner, to ensure that their adaptation plans are not mutually
incompatible, collectively ineffective, or counterproductive.
• Developed States are under a specific obligation to provide continuing and
enhanced support to developing countries in respect of adaptation. Such support
should include financial assistance, technology development and transfer, and
capacity building.
135
3. Obligations related to the provision of support
a. Introduction
462. Climate change mitigation and adaptation actions require significant financial and nonfinancial
resources. Some of the countries least responsible for, and worst affected by,
climate change are also the ones that face the highest resource needs for mitigation and
adaptation. International law requires developed States to provide financial and nonfinancial
support to developing States to support their mitigation and adaptation actions.
463. Below, Antigua and Barbuda discusses the obligations of States in relation to financial
support, which arise, in particular, under the international climate regime and UNCLOS
(sub-section (b)). Antigua and Barbuda then addresses obligations relating to other
forms of support, in particular, support in the form of technology transfer, with
obligations flowing from a variety of sources, including the international climate
regime, obligations under the WTO Agreement, UNCLOS, and the CBD (subsection
(c)).
b. Financial support
464. The expected cost of developing countries’ collective mitigation and adaptation
measures through 2030 is approximately USD 5.8-5.9 trillion.520 The expected cost of
planned mitigation and adaption actions by Antigua and Barbuda alone, during that
period, is approximately USD 1-1.7 billion.521 This is a significant sum for the country,
representing between 65 and 110 percent of its annual GDP.
465. Neither Antigua and Barbuda, nor other developing countries, can be expected to
shoulder this burden alone. International law does not expect them to do so. As
explained in the analysis below, developed States are under a specific obligation to
provide financial assistance to developing States for their mitigation and adaptation
efforts.
520 UNFCCC Standing Committee on Finance, “First Report on the Determination of the Needs of Developing
Country Parties 2021”, p. 7 (available here).
521 Antigua and Barbuda, “Updated Nationally Determined Contribution for the period 2020-2030” (2021)
(available here), p. 23.
136
i. Obligations under the international climate change
regime
466. Among the cornerstone principles of the international climate change regime is the
principle of fairness, equity and CBDR-RC.522 As one specific manifestation of this
principle, the Paris Agreement sets out extensive financing obligations for developed
States to help meet the pressing and uniquely important needs of developing States. In
explaining these obligations, Antigua and Barbuda addresses the existence and nature
of the financing obligations; their extent (i.e., how much financing the obligation
requires); how financing should be allocated between recipients; and transparency
obligations with respect to financing.
(1) Existence and nature of the financing obligation
467. Article 9.1 of the Paris Agreement provides as follows:
Developed country Parties shall provide financial resources to
assist developing country Parties with respect to both mitigation
and adaptation in continuation of their existing obligations under
the Convention.
468. In using the words “shall provide”, the Paris Agreement sets out an obligation to
provide financial resources, and not merely to attempt, aspire, or promise to provide
them. This is further confirmed by Articles 4.5 and 7.13 of the Paris Agreement, which
require that “support” under Article 9 – of which financial resources are an essential
part – “shall be provided” to developing countries for their implementation of
mitigation and adaptation actions respectively. The Paris Agreement is also
unambiguous in assigning this obligation to developed country Parties.
469. The obligation under Article 9.1 requires developed countries to provide financial
support for both mitigation and adaptation needs of developing States. Article 4.5
further emphasises the obligation to provide mitigation financing. Article 4.5 reads as
follows:
Support shall be provided to developing country Parties for the
implementation of this Article, in accordance with Articles 9, 10
and 11, recognizing that enhanced support for developing
country Parties will allow for higher ambition in their actions.
522 See, sub-section III.A.2, above.
137
470. The aim of this financing obligation is to enable developing countries to implement
their obligations under Article 4. Developing countries are required, like developed
countries, to maintain nationally determined contributions in climate mitigation
reflecting their “highest possible ambition”.523 This ambition of developing countries
depends on their respective national circumstances, and can only be “higher” over time
depending on the financial support provided by developed countries.
471. Similarly, Article 7.13 further emphasises the obligation to provide adaptation
financing, given the urgency of such financing for developing countries. Article 7.13
provides that:
Continuous and enhanced international support shall be provided
to developing country Parties for the implementation of
paragraphs 7, 9, 10 and 11 of this Article, in accordance with the
provisions of Article 9, 10 and 11.
472. Article 7.13 establishes a mandatory obligation (“shall”) on Parties to the Paris
Agreement to provide “continuous and enhanced international support” to “developing
country Parties”. The purpose of financial support under this provision is the
implementation of, among others, Article 7.9. Article 7.9 requires Parties to the Paris
Agreement to plan and adopt adaptation measures “as appropriate” to the circumstances
(which include, among others, their respective capacities and availability of financial
support from developed States). To this end, Article 7.13 requires support for
adaptation action to be “continuous” and “enhanced”, i.e., it must be uninterrupted or
unbroken, and of a heightened or intensified degree. 524
(2) Extent of the financing obligation
473. Article 9.1 does not explicitly specify the quantum of financing that must be provided.
However, Article 9.1 does identify the purpose for which financing is to be provided:
“to assist developing country Parties with respect to both mitigation and adaptation”.
474. Article 4.5, in the context of mitigation obligations under the Paris Agreement, requires
that financing under Article 9 “shall be provided to developing country Parties for the
523 Paris Agreement, Article 4.3.
524 See, Oxford English Dictionary, “continuous, adj.” (available here); Oxford English Dictionary, “enhance,
v.” (available here).
138
implementation of this Article”. Similarly, Article 7.13 of the Paris Agreement
provides that “[c]ontinuous and enhanced international support shall be provided to
developing country Parties for the implementation” of their adaptation obligations
under Article 7. The word “for” is used to express a purpose and must be understood
to mean “in order to obtain or secure” something, a thing “at stake” or “risked”.525 Both
provisions, in using the conjunction “for”, confirm that financing provided under the
Agreement must be fit to serve a particular purpose – meeting the mitigation and
adaptation needs of developing countries.
475. The financing provided under Article 9.1 must be of such a quantum that that it can, in
fact, meet this objective. As discussed, in the pre-2030 period, the mitigation and
adaptation needs of developing countries are expected to cost around USD 5.9
trillion.526
476. Another indication of the quantitative extent of the financing obligation is the use of
the terms “enhanced” in Articles 4.5 and 7.13, and the requirement in Article 9.3 that
developed countries take the lead in mobilising climate finance, representing “a
progression beyond previous efforts”. The term “enhanced” (which means “raise[d] in
degree”, “increased”527) and the words “progression beyond previous efforts” indicate
a comparative relationship between the status quo of current financing, and the quantum
of financing required under Article 9.1. The required financing is higher than financing
provided in the status quo or the immediate past. That is, developed countries must
continue to increase the extent of financing, until such financing is sufficient for its
purpose – i.e., to meet the mitigation and adaptation needs of developing countries.
477. While falling short of meeting this financing obligation in full, States have agreed on
certain minimum financing targets, as a contribution towards partial fulfilment of the
obligation. Under the Copenhagen Accord,528 developed country parties to the
UNFCCC committed to “mobilizing jointly USD 100 billion dollars a year by 2020”
525 See, Oxford English Dictionary, “for, prep.” (available here).
526 UNFCCC Standing Committee on Finance, “First Report on the Determination of the Needs of Developing
Country Parties” (available here), p. 7.
527 See, Oxford English Dictionary, “enhance, v.” (available here).
528 The Copenhagen Accord was a UNFCCC COP proposal, which was subsequently adopted as UNFCCC COP,
Decision 2/CP.15, “Copenhagen Accord” (2009) (available here), p. 4.
139
for climate financing of developing countries.529 Parties to the Paris Agreement
reaffirmed and extended this commitment through 2025.530
478. In the same decision, the parties agreed to establish by 2025 a new “collective
quantified goal” (“NCQG”), where the USD 100 billion per year will represent a floor,
and not a ceiling for the requirement of collective mobilisation of climate finance. Most
recently, the parties emphasised the importance of advancing the negotiations on the
NCQG in the course of 2024, taking into consideration “the exigent need to support
implementation” of current NDCs and national adaptation plans.531
479. The achievement by developed countries of mobilising the USD 100 billion floor
annually would go some way towards compliance with the financing obligations in the
Paris Agreement, even though not exhausting the obligations. However, it has been
noted “with deep regret” that developed countries have consistently failed to meet even
this floor for the financing obligation.532 According to a report published in preparation
of the COP Global Stocktake Decision, the real value of financing provided in 2020
was estimated at a mere USD 21-24.5 billion, although formally reported at USD 83.3
billion.533
480. This failure to meet the commitments of the Copenhagen Accord contrasts sharply with
the financial support of USD 5 trillion that countries around the world collectively
deployed in 2020 as fossil fuel subsidies.534 That is, in a single year, countries provided
529 UNFCCC COP, Decision 2/CP.15, “Copenhagen Accord” (2009) (available here), para. 8. The Green Climate
Fund (“GCF”) was established to moderate a significant portion of these funds.
530 UNFCCC COP, Decision 1/CP.21, “Adoption of the Paris Agreement”, UN Doc. FCCC/CP/2015/10/Add. 1,
12 December 2015 (available here) (hereinafter “UNFCCC COP, Decision 1/CP.21, “Adoption of the Paris
Agreement” (2015)”), para. 53. It further highlighted that this mobilisation should take place in the context
of meaningful mitigation actions and transparency on implementation, and in light of the needs and priorities
of developing countries.
531 UNFCCC COP, Draft Decision -/CMA.5, “New collective quantified goal on climate finance”, UN Doc.
FCCC/PA/CMA/2023/L.10, 12 December 2023 (available here), para. 26.
532 See, UNFCCC COP, Decision 1/CMA.3, “Glasgow Climate Pact” (2021), para. 44 (available here).
533 UNFCCC, “Views on the elements for the consideration of outputs component of the first global stocktake:
Synthesis report by the secretariat” (available here), para. 173.
534 See, IMF Working paper, “IMF Fossil Fuel Subsidies Data: 2023 Update” (available here). The total amount
of global subsidies in fossil fuels has gradually increased the past two years, reaching USD 6 trillion in 2021
and USD 7.5 trillion in 2022.
140
around 85 percent of the total mitigation and adaptation costs of all countries for the
period until 2030, as fossil fuel subsidies.
481. These subsidies undermine the impact of climate financing provided, as their amount
significantly outweighs, in absolute terms, the amount of climate financing. For this
reason, the COP Global Stocktake Decision called on parties to the Paris Agreement to
contribute in “phasing out inefficient fossil fuel subsidies that do not address energy
poverty or just transitions”.535 Furthermore, fossil fuel subsidies constitute backwards
steps for the parties of the Paris Agreement, in their journey to fulfil their adaptation
and mitigation commitments. This is because such subsidies incentivise the ongoing
use of fossil fuels (and thus further emissions) by rendering them artificially
competitive with renewable sources of energy, locking in fossil fuel dependency and
making the clean energy transition more difficult and costly.
482. Therefore, the provision of massive fossil fuel subsidies significantly detracts from the
achievement of the objectives of the Paris Agreement, and significantly increases the
amount of financial resources needed to meet the Paris Agreement mitigation and
adaptation commitments. In continuing to provide massive fossil fuel subsidies, yet
failing to increase climate finance commensurately, States devote resources
incentivising the ongoing use of fossil fuels, when these resources could be used to
reduce the shortfall in climate finance and to accelerate a just transition. This
undermines the obligations under the Paris Agreement.
483. Finally, it should be emphasised that the extent of financing discussed in this section is
specifically as regards to support for mitigation and adaptation, and is not exhaustive
as to the total financial burdens of States in response to the climate crisis writ large.
Most notably, as explained above,536 as a result of States’ historical emissions, warming
is already occurring at a pace and scale that cannot be entirely addressed by adaptation
measures; even with robust adaptation efforts, harms (i.e., loss and damage) are already,
and will continue to, occur, including for Antigua and Barbuda specifically. These
535 UNFCCC COP, Draft Decision -/CMA.5, “Outcome of the first global stocktake” (2023) (available here),
para. 28(h).
536 See, sub-section III.B.2, para. 437, above.
141
harms may implicate State responsibility to provide payments beyond those for
mitigation and adaptation specifically.
(3) Allocation of finances made available pursuant to the obligation
484. Any financial support made available by the developed countries in the discharge of
their obligations under the climate regime must be allocated among the eligible
recipients. The Paris Agreement sets out certain principles that guide such allocation.
485. Under Article 9.4 of the Paris Agreement, financing should take into account the
specific “strategies”, “needs and priorities” of developing countries. Among
developing countries, special attention must be given to those that are “particularly
vulnerable to the adverse effects of climate change and have significant capacity
constraints”, such as least-developed countries and SIDS.537 Financing should be
allocated in light of these considerations and with the aim to achieve a balance between
adaptation and mitigation.
486. When allocating financing for mitigation, Article 4 provides useful context, recognising
that developing countries “will take longer” to reach peak emissions. All parties are
required to undertake mitigation action reflecting their “highest possible ambition”,
which, for developing countries, will depend on the financial support received.
487. Similarly, in apportioning financial support for adaptation, Article 7.2 provides
meaningful context by recognising the “urgent and immediate needs of those
developing country Parties that are particularly vulnerable to the adverse effects of
climate change”. Article 7.4 further recognises that “greater adaptation needs can
involve greater adaptation costs”.
488. These provisions, along with the cornerstone principle of fairness, equity and CBDRRC,
require SIDS and other uniquely vulnerable countries to enjoy priority in the
allocation of climate financing. This is and should remain the case when assessing the
allocation of climate financing in the multilateral system established under the
UNFCCC and Paris Agreement regime. This prioritisation is particularly important in
537 See, Paris Agreement, Articles 9.4 and 10.6; see also, UNFCCC, Article 4.4, which requires developed
countries to “assist the developing country Parties that are particularly vulnerable to the adverse effects of
climate change in meeting costs of adaptation to those adverse effects”.
142
the allocation of adaptation financing – while SIDS have made, and continue to make
a minimal contribution to GHG emissions, they face a disproportionate share of urgent
adaptation needs and, thus, urgent adaptation costs. They should, therefore, receive a
larger share of support.
489. In this context, Antigua and Barbuda emphasises that “strategies”, “needs and
priorities” of a developing country recipient must be taken into account holistically:
eligible recipients should not be deprived of access to financing through the use of
artificial criteria. Antigua and Barbuda is concerned over the emerging practice of
using such artificial criteria when allocating so-called “climate financing” through
bilateral channels, or, in certain circumstances, development financing. This includes,
for example, Gross National Income (“GNI”) per capita, the metric typically used for
the allocation of financing for developing countries, but one which is not multilaterally
agreed as appropriately calibrated for allocating financing for climate change-related
needs.538
490. Antigua and Barbuda maintains that these artificial and arbitrary criteria should not be
used in a manner that circumvents the obligation of States to provide support. Certain
SIDS (including Antigua and Barbuda) are classified as high income countries because
of their relatively high GNI per-capita, even though this outcome is largely an artifact
of their micro-population. As a result, certain SIDS, including Antigua and Barbuda,
are ineligible for many concessional financing instruments provided by e.g., World
Bank, the Asian Development Bank and the African Development Bank.539
491. The reality for States vulnerable to climate change is far more complex than a GNI percapita
metric can account for.540 The metric fails entirely to account for factors such as,
among others, income disparity, inequality or country-specific vulnerabilities.541 Nor
does it take into consideration the real-word costs of mitigation and, most importantly
538 United Nations Office of the High Representative for the Least Developed Countries, Landlocked Developing
Countries and Small Island Developing States, “High Level Plan on the Development of a Multi-Dimensional
Vulnerability Index”, September 2023 (available here), p. 51.
539 UNFCCC, Assessment and Overview of Climate Finance Flows: Antigua and Barbuda 2014-2017: Methods
to assess climate finance (available here), pp. 26-27.
540 United Nations Office of the High Representative for the Least Developed Countries, Landlocked Developing
Countries and Small Island Developing States, “High Level Plan on the Development of a Multi-Dimensional
Vulnerability Index” (available here), p.13.
541 See, footnote 540, above.
143
for such countries, adaptation measures. It reveals nothing about the ability of a micropopulation
to meet the substantial financial costs of its mitigation and adaptation
measures. For instance, it fails to take into account that the limited scale of investment
in high-income and micro-population SIDS results in their limited capacity to repay
any loans that form part of climate financing, compared to larger countries with
economies of scale. The “high income” label cannot be used as a device by developed
countries to avoid their obligations to provide much-needed climate finance to the most
vulnerable SIDS.
492. At the same time, there is ample information available to assist in the appropriate
allocation of resources. For one, developing countries’ own NDC communications
shed light on their “needs and priorities”, identifying specific financing needs at the
individual project level, and special vulnerabilities due to geographical circumstances.
They also communicate what share of the cost they can carry and the capacity
constraints.
493. There are also external sources and scientific tools available to determine appropriate
allocations. For example, the UN is in the course of developing a “Multidimensional
Vulnerability Index” (“MVI”), a metric dedicated to assessing developing countries’
vulnerabilities to climate change.542 Preliminary scores are already available, assigned
based on countries’ structural vulnerability and lack of resilience. The MVI rationale
accounts for the small historic carbon footprint of the countries – recognising that all
SIDS, together, are responsible for only 0.2 percent of the global GHG emissions.
Thus, Antigua and Barbuda maintains, that there are different metrics, such as the MVI,
with an assessment method that duly takes into account the special circumstances of
SIDS. Such metrics are aligned to a greater degree with the allocation principles
already enshrined in the Paris Agreement obligations on provision of financial support.
494. As shown above, the Paris Agreement provides – through its transparency framework,
including the NDC communications – an avenue through which developing countries
make public their financing needs and priorities; this avenue, coupled with public and
scientific sources, allow an equitable basis for apportioning the available climate
542 See, UN, “Final Report of the High Level Panel on the Development of a Multidimensional Vulnerability
Index”, February 2024 (available here).
144
finance. For any allocation to be equitable, and consistent with the Paris Agreement,
SIDS must be preferred, due to their special and unique vulnerabilities. Artificial and
misleading methods of allocation, based on partial information, cannot be used to
deprive eligible SIDS of much needed financing.
(4) Transparency obligations
495. Article 9.5 of the Paris Agreement provides that developed country parties “shall
biennially communicate indicative quantitative and qualitative information” in relation
to the fulfilment of their financing obligations. Importantly, developed country parties
are required to communicate the projected levels of public financial resources that they
intend to provide to developing country parties (“ex ante” transparency).
496. Furthermore, under Article 9.7 of the Paris Agreement, they must also communicate
information on the financial support already provided to developing country Parties
biennially (“ex post” transparency).
497. These transparency obligations aim to enhance predictability and clarity of financing
provided by developed countries in discharge of their obligations under the Paris
Agreement.543 If fulfilled, the transparency obligations allow monitoring and
verification of compliance with the financing obligations.
498. In 2018, through a COP Decision, the parties to the Paris Agreement collectively
requested developed countries to submit their first biennial report in 2020, specifying a
list of information to be included.544 Among other things, this list requests information
on how financial support “effectively addresses” the needs and priorities of developing
country Parties, and specifically of SIDS and other particularly vulnerable countries.
In their first reports in 2020, many Parties disclosed difficulties in accurately reporting
“effective” financial support: national circumstances might obstruct the planning or the
actual disbursement of projected financing.545 In the second round of reporting, in
543 UNFCCC COP, Decision 12/CMA.1, “Identification of the information to be provided by Parties in
accordance with Article 9, paragraph 5, of the Paris Agreement”, UN Doc. FCCC/PA/CMA/2018/3/Add.1,
15 December 2018 (available here).
544 See, footnote 543, above, para. 4.
545 UNFCCC COP, Synthesis Report, “First biennial communications in accordance with Article 9, paragraph 5,
of the Paris Agreement”, UN Doc. FCCC/PA/CMA/2021/3, 20 September 2021 (available here).
145
2023, only 5 out of the 35 reporting countries submitted “ex post” financing
information.
ii. Obligations under the UNCLOS
499. In Section III.B.1, Antigua and Barbuda discussed (i) the general obligation for States,
under Article 192 of the UNCLOS to protect and preserve the marine environment, and
(ii) its specific expression in Article 194, requiring States to prevent, control and reduce
pollution of the marine environment.546 In that Section, Antigua and Barbuda recalled
the existential threat posed by anthropogenic GHG emissions to the marine
environment, and explained that they engage the obligations of States under Articles
192, 194 and related UNCLOS provisions.
500. In particular, as discussed above,547 Article 192 of the UNCLOS, read with Article 197,
requires States to cooperate in the establishment of international rules and standards to
protect and preserve the marine environment, and to abide by such rules and standards
once established. In that Section, Antigua and Barbuda also explained that the
international climate change regime represents such international rules and standards
with which Articles 192 and 197 of the UNCLOS require compliance. The financing
obligations discussed in this section, being an integral part of the international climate
change regime, share that characteristic. As such, Article 192, read with Article 197, of
the UNCLOS establish an additional and concurrent obligation on UNCLOS parties to
abide by the financing obligations of the international climate regime, discussed in the
preceding sections.
iii. Obligations under the CBD
501. States are also under an obligation to provide financial support for the mitigation and
adaptation needs of developing countries under the CBD. Antigua and Barbuda has
discussed above the important interaction between biodiversity and climate change, and
the particular significance of biodiversity in SIDS.548 Parties to the CBD are required
to undertake measures for the conservation and sustainable use of biological diversity.
546 See, paras. 385-403, above.
547 See, paras. 385-403, above.
548 See, sub-section II.C.2, above.
146
In this context, CBD parties undertake actions relating to climate change adaptation,
and recognise the need to coordinate action with UNFCCC Parties.549
502. The very first Article of the CBD identifies “appropriate funding” as one of the means
through which the objectives of the CBD are to be pursued. Article 20(2) of the CBD
requires developed country Parties to provide “new and additional financial resources”
to developing countries to meet the cost of implementing their obligations under the
CBD. Once again, the provision of such financing is mandatory (“shall”) and is not
discharged solely through an intention, effort, or promise to provide such finance. The
use of the words “new” and “additional” require an increase in the quantum of
financing, compared to the status quo.
503. Article 20(4) recognises that “[t]he extent to which developing country Parties will
effectively implement their commitments under this Convention will depend on the
effective implementation by developed country Parties of their commitments under this
Convention related to financial resources and transfer of technology”. That is, in
addition to requiring developed countries to provide financial support, the CBD
recognises that the adherence to this obligation by developed countries is a precondition
for developing countries meeting their own obligations.
504. Finally, Article 20(7) requires that in providing such financing, “special situation of
developing countries, including those that are most environmentally vulnerable” must
be considered. Once again, this provision requires that the countries which are most
vulnerable, such as SIDS, should receive a larger share of any financial support.
Furthermore, Article 20(7) would require a consideration of actual circumstances of
the vulnerable countries, and would not permit the exclusion of eligible SIDS based on
artificial criteria like GNI per capita (as discussed above).
iv. Summary of financing obligations
505. In light of the above discussion, Antigua and Barbuda identifies the following specific
obligations of States in respect of financing, under the international climate change
regime, UNCLOS, and CBD:
549 Recommendation of the CBD Subsidiary Body on Scientific, Technical and Technological Advice,
CBD/SBSTTA/25/L.9, October 2023 (available here), p. 2.
147
• First, developed States are under a specific obligation to provide support in the form
of climate finance to developing countries, in order to aid developing countries’ in
effectively implementing their responses to climate change.
• Second, developed States are under a specific obligation to ensure that the financing
is continuously increased until it is quantitatively sufficient to meet the mitigation
and adaptation needs of developing countries. Developed States are under a specific
obligation to immediately deliver at least the USD 100 billion per year floor set out
in the Copenhagen Accord.
• Third, States are under a specific obligation to ensure that the allocation of any
financial support takes fully into account the needs and priorities, and unique
vulnerabilities, of the potential recipients. In any such allocation, SIDS and other
particularly vulnerable States must receive preference. This is particularly true for
adaptation financing, given the urgent adaptation needs faced by SIDS and other
particularly vulnerable developing countries.
• Fourth, developed States are under the specific obligation to communicate
biennially various information on financial support they intend to provide and have
provided to developing States.
c. Technology support
506. Meeting the urgent mitigation and adaptation needs of vulnerable developing countries
requires the rapid development and deployment of novel technologies, in addition to
financial resources. As such, developed States are under an obligation to take the lead
in the development of such technologies, and assist developing countries to deploy
these technologies in meeting their mitigation and adaptation needs, including through
technology transfer. Specifically, Antigua and Barbuda identifies such obligations in
several provisions of the international climate change regime, UNCLOS, the CBD, and
law of the World Trade Organization, in this sub-section.
i. Obligations under the international climate change
regime
507. In addition to the financing obligations identified above, the international climate
change regime also requires developed countries to provide additional forms of support,
particularly technology support, to developing countries. Furthermore, developed
countries are encouraged to “enhance support for capacity-building actions in
developing country Parties”.550 Capacity building should facilitate, among other things,
550 Paris Agreement, Article 11.3.
148
technology development and access to climate finance by developing countries.551
These forms of support are to be made available to meet the mitigation and adaptation
needs of developing countries.
508. With respect to technology support, Article 10.2 of the Paris Agreement provides as
follows:
Parties, noting the importance of technology for the
implementation of mitigation and adaptation actions under this
Agreement and recognizing existing technology deployment and
dissemination efforts, shall strengthen cooperative action on
technology development and transfer.
509. In using the words “shall strengthen”, the Paris Agreement sets out an obligation for all
Parties to cooperate in technology development and transfer. Such cooperative action
is required “for the implementation of mitigation and adaptation actions”. Therefore,
the extent of the required cooperation is informed by the aim of this provision, which
is to support the implementation of adaptation and mitigation measures by all Parties.552
510. Meeting the urgent mitigation and adaptation needs of vulnerable developing countries
requires the rapid development and deployment of novel technologies, in addition to
financial resources. As such, technology support, in the form of cooperation for
technology development and transfer, is particularly important for developing
countries. Articles 4.5 and 7.13 of the Paris Agreement, by reference to Article 10,
require developed countries to provide technology support specifically for the
implementation of mitigation and adaptation obligations by developing countries.
Technology support must be, like financial support, continuous and enhanced.
511. Furthermore, Article 10.6 of the Paris Agreement recognises that support, including
financial support “shall be provided” to developing countries to enable them to
participate in the technology cooperation envisaged by Article 10. That is, in addition
to the general financing obligations discussed above, Article 10.6 requires financial
support specifically in order to strengthen technology cooperation under Article 10.2.
551 Paris Agreement, Article 11.1.
552 See also, Paris Agreement, Article 10.4.
149
The two types of independent support envisaged under the Paris Agreement, financial
and technology, are thus complementary.553
512. Article 10.3 the Paris Agreement establishes a Technology Mechanism for
implementation of the obligations. The parties to the Paris Agreement recently
expressed their concern for the lack of financial support for the work of this mechanism
and called for increased transparency on the progress of this mechanism’s efforts.554
The 2023-2027 programme of the Technology Mechanism aims to accelerate the
deployment of transformative climate technologies that are urgently required to tackle
climate change.555
513. In sum, developed Parties are under an obligation to provide technology support to
developing countries to meet their mitigation and adaptation needs. For the same
reasons discussed in relation to financial support, the extent of such support must be
continuously increased in comparison to the status quo, until it is sufficient to meet the
mitigation and adaptation needs of developing countries. Finally, any available support
must be allocated equitably such that SIDS and other particularly vulnerable developing
countries are prioritised. As discussed above in the context of allocation of financial
support, artificial criteria based on partial information, like GNI per-capita, should not
be used to deprive deserving SIDS of much needed assistance.
ii. Obligations under UNCLOS
514. As discussed above, anthropogenic GHG emissions and their existential threat to the
marine environment engage obligations of States under Articles 192, 194 and related
provisions of the UNCLOS.556 In particular, as discussed in relation to the financing
obligations above, Article 192 read with Article 197 require UNCLOS Parties to abide
by the commitments they have undertaken in the international climate change regime.
Since the obligations concerning technology support, discussed above, are an integral
part of the international climate change regime, UNCLOS Parties are under a separate
553 See also, Green Climate Fund, “GCF in Brief: Support for Technology”, 4 December 2018 (available here).
554 See, UNFCCC COP, Draft Decision -/CMA.5, “Enhancing climate technology development and transfer to
support implementation of the Paris Agreement”, UN Doc. FCCC/SB/2023, 6 December 2023 (available here).
555 Joint Work Programme of the UNFCCC Technology Mechanism for 2023–2027, “Accelerating Climate
Action through Technology Development and Transfer” (available here).
556 See, paras. 385-403, above.
150
and concurrent obligation under Article 192, read with Article 197, of the UNCLOS to
abide by those obligations.
515. Further, Part XII of the UNCLOS, which provides obligations for protection and
preservation of the marine environment, includes Section 3 dedicated to technical
assistance for developing States. Of particular note, Article 202(a) from Section 3 of
Part XII provides that:
States shall … promote programmes of scientific, educational,
technical and other assistance to developing States for the
protection and preservation of the marine environment and the
prevention, reduction and control of marine pollution.
516. Thus, the “assistance” to be provided under UNCLOS is for a dedicated purpose: the
fulfilment of developing States’ substantive obligations under UNCLOS Articles 192
(which sets forth a general obligation in respect of protection and preservation of the
marine environment) and 194 (which sets forth obligations in respect of prevention,
reduction and control of pollution). Article 202 further specifies that the “assistance”
provided “shall” take specific forms outlined in subparagraphs (i) through (v), including
(among others): training, supplying equipment and facilities, and capacity building.
517. Other Parts of the UNCLOS contain specific obligations relating to technology
transfers. Article 242(2) under Part XIII of the UNCLOS (“Marine Scientific
Research”) requires sharing of “information necessary to prevent and control damage
… to the marine environment”. Article 244(2) requires UNCLOS parties to “actively
promote the flow of scientific data and information and the transfer of knowledge
resulting from marine scientific research, especially to developing States…”.
iii. Obligations under the CBD
518. Relevant technology support obligations also arise under the CBD. Antigua and
Barbuda has discussed the important interaction between biodiversity and climate
change, and the particular significance of biodiversity in SIDS.557 Parties to the CBD
are required to undertake measures for the conservation and sustainable use of
biological diversity. In this context, CBD Parties undertake actions relating to climate
557 See, sub-section II.C.2, above.
151
change adaptation, and recognise the need to coordinate action with UNFCCC
parties.558
519. The CBD, in its very first Article refers to “appropriate transfer of relevant
technologies” as a means for pursuing the CBD’s objectives, and in Article 16(1) states
that access to technology is an “essential element[] for the attainment of the objectives
of [the] Convention”. Article 16(2) provides as follows:
Access to and transfer of technology referred to in paragraph 1
above to developing countries shall be provided and/or
facilitated under fair and most favourable terms, including on
concessional and preferential terms where mutually agreed, and,
where necessary, in accordance with the financial mechanism….
520. Accordingly, under Article 16, CBD parties are required (“shall”) to provide and/or
facilitate access to and transfers of technology to developing countries, under fair and
most favourable terms. This obligation shall be discharged through appropriate
legislative, administrative or policy measures on behalf of CBD Parties, including
through mobilisation of the private sector in their territories. Parties are also required
to cooperate in order to ensure that intellectual property rights protected under national
and international law do not run counter to the CBD objectives and the obligation to
provide technology transfers.559
iv. Obligations under the WTO regime
521. Technology support obligations owed by developed States, and relevant for climate
change mitigation and adaption actions, arise under other international law regimes,
including international trade law.
522. To recall, the WTO Agreement on Trade Related Intellectual Property Rights (“TRIPS
Agreement”) requires States to protect certain forms of intellectual property rights.560
The preamble to the TRIPS Agreement recalls the “developmental and technological
objectives” underlying the policy of protecting intellectual property rights, and
558 Convention on Biodiversity, Subsidiary Body on Scientific, Technical and Technological Advice,
“Biodiversity and climate change: Draft recommendation submitted by the Chair”, UNEP Doc.
CBD/SBSTTA/25/L.9 (available here), p. 2.
559 See, Convention on Biodiversity, Articles 16(2)-16(5).
560 See, TRIPS Agreement, Articles 1.1, 9, 10, 14, 15, 22, 23, 25, 27, 35 and 39.
152
recognises the “the special needs of the least-developed country Members”. Article 7
of the TRIPS Agreement requires that the protection of intellectual property rights
“should contribute”, inter alia, to “transfer and dissemination of technology” in a
manner “conducive to social and economic welfare”.
523. In line with these objectives, Article 66.2 of the TRIPS Agreement provides as follows:
Developed country Members shall provide incentives to
enterprises and institutions in their territories for the purpose of
promoting and encouraging technology transfer to leastdeveloped
country Members in order to enable them to create a
sound and viable technological base.
524. The TRIPS Agreement takes a different approach, compared to the Paris Agreement,
with respect to the obligations of developed States in relation to technology support.
While the focus of the Paris Agreement is direct support by developed countries to
certain developing countries, the TRIPS Agreement requires developed countries to
take action to incentivise private action. In particular, Article 66.2 requires developed
countries to provide incentives to encourage technology transfers by their own
institutions and enterprises to LDCs. This requirement must be understood in light of
the objectives of the TRIPS Agreement, which aims to contribute in the transfer of
technology “in a manner conducive to social and economic welfare”.
525. Further, while the approaches are different, they are complementary; States may
simultaneously provide direct support themselves, and incentivise the provision of
support by private actors. In this regard, as Antigua and Barbuda has explained, WTO
law is not to be “read in clinical isolation from public international law”.561 Here,
therefore, the way that the technology transfer obligations under the Paris Agreement
have been interpreted and applied, including through States’ real-world practice, could,
in principle, be relevant to how States implement their obligations under Article 66.2
of the TRIPS Agreement.
526. Climate change and its impact are undoubtedly matters of “social and economic
welfare”. As discussed in Section 0 of this Written Statement, climate change threatens
life, livelihood, the enjoyment of the most basic human rights, and the very existence
561 Appellate Body Report, US – Gasoline, p. 17.
153
of peoples and their ways of life in many parts of the world. Thus, the ability of LDCs
to respond to climate change, through adaptation and mitigation measures, certainly
constitute matters of social and economic welfare, through a national and international
lens. Accordingly, developed countries are required to incentivise their institutions and
enterprises towards the transfer of climate-related technologies to LDCs. Indeed, the
reports submitted to the WTO Council for the TRIPS Agreement reveal that
environment and climate change is one of the three most important areas of incentives
for technology transfer, provided under Article 66.2.562
v. Summary of technology transfer obligations
527. In light of the above discussion, Antigua and Barbuda identifies the following specific
obligations of States in respect of technology support, under the international climate
change regime, the UNCLOS, WTO law, and the CBD:
• First, developed States are under a specific obligation to provide technology
support to mitigation and adaptation needs of developing countries. Such support
should include, inter alia, the creation of incentives for private institutions to
transfer technology to developing countries for their mitigation and adaptation
needs.
• Second, developed States are under a specific obligation to ensure that the
technology support is continuously increased until it is sufficient to meet the
mitigation and adaptation needs of developing countries.
• Third, States are under a specific obligation to ensure that the allocation of any
technology support takes fully into account the needs and priorities, and unique
vulnerabilities, of the potential recipients. In any such allocation, SIDS and other
particularly vulnerable States must receive preference.
562 WTO Economic Research and Statistics Division, “Reflection on the Implementation of Decision on
Implementation of Article 66.2 of the TRIPS Agreement: Incentive for Technology Transfer to Least-
Developed Countries” (available here), p. 8.
154
IV. QUESTION (B): LEGAL CONSEQUENCES
A. Introduction
528. The second question asked of the Court is:
(b) What are the legal consequences under these obligations for States where
they, by their acts and omissions, have caused significant harm to the climate
system and other parts of the environment, with respect to:
(i) States, including, in particular, small island developing States, which
due to their geographical circumstances and level of development, are injured
or specially affected by or are particularly vulnerable to the adverse effects of
climate change?
(ii) Peoples and individuals of the present and future generations affected
by the adverse effects of climate change?
529. The second question calls for a straightforward exposition of the customary
international law rules of State responsibility. The legal consequences for States where
they have caused significant harm to the climate system and other parts of the
environment (i.e., “loss and damage”) in breach of their obligations are that: (i) they
will be responsible for such breaches and (ii) they will be obliged to make full
reparation for the harm caused by them. These principles are of particular significance
for those States – such as Antigua and Barbuda – that have made a negligible
contribution to the climate crisis, but suffer a disproportionate level of the resulting loss
and damage.
530. There is nothing special about harm to the climate system or other parts of the
environment caused by GHG emissions as regards the establishment of State
responsibility, the general content of that responsibility, or the invocation of such
responsibility by States and other parties so entitled under relevant treaty regimes. As
a UN treaty body has recognised, “[t]he collective nature of the causation of climate
change does not absolve the State party of its individual responsibility that may derive
from the harm that the emissions originating within its territory may cause”.563 While
complexities arise in connection with how to apportion liability to make full reparation
among a plurality of responsible States, that is a separate and subsequent question to
563 Committee on the Rights of the Child, Sacchi v. Argentina et al., 10 August 2021, para. 10.10, see also,
para. 545 below.
155
the operation of the core principles of the law of State responsibility: the establishment,
general content and invocation of responsibility.
531. This Section of the Written Statement identifies the law governing legal consequences
(sub-section IV.B), and then sets out the general principles governing the
establishment, content and invocation of State responsibility (sub-section IV.C). These
principles are then applied in the context of climate change caused by anthropogenic
GHG emissions, focusing on breaches of the obligations identified in the preceding subsections
(sub-section IV.D).
B. The law governing legal consequences
532. The legal consequences of a breach of an international obligation are governed by the
customary international law rules on State responsibility. These rules are codified in
the ILC Articles on the Responsibility of States for Internationally Wrongful Acts
(“Articles on State Responsibility”).564
533. There are no lex specialis secondary rules governing the consequences of a breach of
the obligations addressed in Section III that would operate to displace the rules codified
in the ILC’s Articles on State Responsibility.565 None of the treaties surveyed in
Section III contain any such rules. In particular, the UNFCCC and the Paris Agreement
contain no provisions dealing with the consequences of a breach of obligations
contained in those treaties,566 and the COP Decision adopting the Paris Agreement
expressly excludes questions of liability and compensation in respect of loss and
damage.567 Therefore, Antigua and Barbuda submits, the only conclusion is that the
564 ILC, Articles on Responsibility of States for Internationally Wrongful Acts with commentaries, ILC Yearbook
2001, vol. II, Part Two (hereinafter “ILC, Articles on State Responsibility”).
565 ILC, Articles on State Responsibility, Article 55.
566 The general provisions on compliance mechanisms (UNFCCC, Article 13; Paris Agreement, Article 15) and
dispute resolution (UNFCCC, Article 14; Paris Agreement, Article 24) do not provide lex specialis secondary
rules governing the consequences of breach.
567 UNFCCC COP, Decision 1/CP.21, “Adoption of the Paris Agreement” (2015), para. 51 (“Article 8 of the
Agreement does not involve or provide a basis for any liability or compensation”). Paris Agreement,
Article 8(3) (“Parties should enhance understanding, action and support … with respect to loss and damage
associated with the adverse effects of climate change”). The mandate of the Warsaw International Mechanism
for Loss and Damage associated with Climate Change Impacts does not extend to questions of responsibility
(see UNFCCC COP, Decision 2/CP.19, “Warsaw international mechanism for loss and damage associated
with climate change impacts”, UN Doc. FCCC/CP/2013/10/Add.1, 29 November 2013 (available here)).
156
customary rules of international law must apply, especially where a set of primary rules
is established without secondary rules.
C. The legal consequences for responsible States
1. The establishment of State responsibility
534. Pursuant to the cornerstone rules codified in Articles 1-2 of the Articles on State
Responsibility, an internationally wrongful act for which a State will be responsible
consists of an act or omission that (i) is attributable to the State and (ii) constitutes a
breach of an international obligation of that State.568
535. As regards attribution, the cardinal rule is that a State is responsible only for its own
wrongful conduct.569 This includes the State’s own actions and its own omissions, such
as failing sufficiently to regulate the conduct of private emitters of GHG within its
territory or subject to its jurisdiction.
536. As regards breach, a State breaches an obligation if it fails to conduct itself in
conformity with what is required of it by that obligation.570 Such a breach may be
instantaneous, or may continue in time,571 as will be the case where States are, for
example, failing in their obligation of due diligence to prevent significant
environmental harm caused by anthropogenic emissions. As a general matter and
unless otherwise specified by the primary rule, the existence of damage is not required
in order to establish a breach of an international obligation.572 Damage is only relevant
568 ILC, Articles on State Responsibility, Articles 1-2 and 12. It is also necessary that there be no justification
that precludes wrongfulness, i.e., consent, self-defence, counter-measures and necessity (see, Articles 20-22
and 25). None of these is relevant in the context of emissions-related damage to the climate system and other
parts of the environment.
569 Former colonies are not responsible for wrongful acts involving historical emissions that emanated from their
territories prior to their independence. The responsibility lies solely with the former colonial powers
themselves. The relevant customary international law rule applicable in the context of decolonisation is that
a formerly colonised State is not responsible for the internationally wrongful acts of its colonial predecessor:
ILC, Second Report on succession of States in respect of State responsibility by Pavel Šturma, Special
Rapporteur, UN Doc. A/CN.4/719, 6 April 2018, draft Articles 6 and 9(1)(c) and paras. 124 and 130; The
Institute of International Law’s 2015 Resolution on State Succession and State Responsibility (2015),
Article 16. The only exception is where a formerly colonised State expressly consents to assume such
responsibility (e.g., Gabčíkovo-Nagymaros, p. 81, para. 151; see also, James Crawford, State Responsibility
(Cambridge University Press, 2013), pp. 446-447).
570 ILC, Articles on State Responsibility, Article 12.
571 ILC, Articles on State Responsibility, Article 14.
572 See, Article 14(3) as regards a necessary condition for breach of an obligation to prevent: the occurrence of
the event sought to be prevented. See also, Bosnia Genocide, pp. 221-222, para. 431 (but see also, p. 221,
para. 430 as regards the absence of a requirement of causation between the breach and the occurrence of the
157
to the question of whether responsibility entails a duty to make reparations through
restitution, compensation and/or satisfaction, as explained below.
2. The content of State responsibility
a. The duties of compliance, cessation and non-repetition
537. States are obliged to comply with all obligations binding on them, including those that
they have breached or of which they are in continuing breach.573
538. States are also obliged to cease continuing wrongful conduct and return to a state of
compliance with the obligation in question immediately or as rapidly as possible.574
This duty of cessation – and the right of States to demand cessation of a continuing
wrongful act, even in the absence of damage – is of crucial importance in protecting the
environment in the face of continuing wrongs. This is particularly so in cases where
the continuation of the breach compounds the damage occurring, as in the case with
anthropogenic GHG emissions. A declaration that the responsible State has a duty to
cease its continuing breach will also be the decisive remedy sought where the damage
caused may not yet have been sustained and thus reparation is not yet available,575 as
may be the case with recent breaches involving GHG emissions.
539. Where the circumstances so require, responsible States are also obliged to offer
appropriate assurances and guarantees of non-repetition.576 Such measures are required
where there is a need to safeguard against the continuation or repetition of wrongful
acts because there is, for example, an indication of bad faith on the part of the
event). As noted at paras. 298-303, and with reference to sub-section II.C above, this condition is already met
as regards the general obligation of prevention because significant harm to the environment from GHG
emissions is already occurring.
573 See, the customary rule codified in the VCLT, Article 26 (“Pacta sunt servanda”); ILC, Articles on State
Responsibility, Article 29 (“Continued duty of performance”); and Wall Advisory Opinion, p. 197, para. 149.
574 ILC, Articles on State Responsibility, Article 30(a); Wall Advisory Opinion, p. 197, para. 150; Military and
Paramilitary Activities, p. 149 (dispositif, para. 12); United States Diplomatic and Consular Staff in Tehran,
Judgment, I.C.J. Reports 1980, pp. 44-45, para. 95 (dispositif paras. 1 and 3); Haya de la Torre Case,
Judgment, I.C.J. Reports 1951, p. 82. See also, Legal Consequences of the Separation of the Chagos
Archipelago from Mauritius in 1965, Advisory Opinion, I.C.J. Reports 2019 (hereinafter “Chagos Advisory
Opinion”), p. 44 (dispositif para. 4: “under an obligation to bring to an end its [continuing breach] as rapidly
as possible”).
575 Other than perhaps a declaration of breach as satisfaction.
576 ILC, Articles on State Responsibility, Article 30(b).
158
responsible State577 or some other reason to believe that violations will continue or be
repeated in the future.578 Guarantees of non-repetition can include requiring specific
preventive measures by the responsible State to avoid breaches in the future, such as
the modification or repeal of legislation.579
b. The obligation to make full reparation for injury caused by
internationally wrongful acts
540. It is a long-established and fundamental rule of international law that States are obliged
to make “full reparation for the injury caused by an internationally wrongful act”,580
which “must, as far as possible, wipe out all the consequences of the illegal act and reestablish
the situation which would, in all probability, have existed if that act had not
been committed”.581 This duty to make full reparation arises automatically upon the
breach of an international obligation (without need for any action on the part of an
injured State).582 As such, it continues and accumulates for so long as the State continues
to be in breach of the obligation in question. The Court has repeatedly affirmed the
obligation to make full reparation in cases involving environmental damage.583
541. Where a State is in breach an obligation, two conditions trigger the duty to make full
reparation: (i) the existence of injury and (ii) a causal relationship between the wrongful
act and the injury sustained.584 These are addressed below.
577 Pulp Mills, p. 105, para. 278; Certain Activities (Merits), p. 717, para. 141.
578 ILC, Articles on State Responsibility, Article 30(b), commentary, paras. 9 and 11-12.
579 ILC, Articles on State Responsibility, Article 30(b), commentary, paras. 12-13, and in particular footnote 447
noting that, in Trail Smelter, the tribunal specifically ordered measures to be adopted that were designed to
“prevent future significant fumigations in the United States” (p. 1934), and citing to multiple decisions of
human rights bodies to modify or repeal legislation.
580 ILC, Articles on State Responsibility, Article 31; Factory at Chorzów, Jurisdiction, Judgment No. 8, 1927,
P.C.I.J., Series A, No. 9, p. 21.
581 Factory at Chorzów, Merits, Judgment No. 13, 1928, P.C.I.J., Series A, No. 17, p. 47; see also, Certain
Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua), Compensation, Judgment,
I.C.J. Reports 2018 (hereinafter “Certain Activities (Compensation)”), p. 25, para. 29. It is also necessary
that there be no circumstance precluding responsibility (i.e., force majeure and distress: ILC, Articles on State
Responsibility, Articles 23-24) which are, in any event, not relevant as regards GHG emissions.
582 ILC, Articles on State Responsibility, Article 31, commentary para. 4.
583 Certain Activities (Compensation), pp. 25-26, paras. 29-30 and p. 28, para. 41; Armed Activities on the
Territory of the Congo (Democratic Republic of the Congo v. Uganda), Reparations, Judgment, I.C.J. Reports
2022 (hereinafter “Armed Activities (Reparations)”), p. 122, para. 348.
584 This type of causation is to be distinguished from causation that is required by the primary obligation.
159
i. Injury
542. As regards the existence of injury, as summarised in sub-sections II.B and II.C, the
scientific evidence is undeniably clear that anthropogenic emissions leading to climate
change are already causing severe, and in some cases, irreversible, harm to the
environment, with equally severe consequences for human populations.585 Further
global warming up to 1.5°C is projected to cause “unavoidable increases in multiple
climate hazards and present multiple risks to ecosystems and humans (very high
confidence)”.586 The “risks and projected adverse impacts and related losses and
damage from climate change will escalate with every increment of global warming”
(“very high confidence”).587
543. In respect of more specific injuries at issue in particular cases, the Court has repeatedly
recognised that the absence of evidence of the precise extent of material damage will
not necessarily preclude an obligation to make reparation.588 If there are evidential
challenges, an assessment of the existence and extent of the damage can be “within the
range of possibilities indicated by the evidence” and “based on reasonable estimates”
for which the Court can then award the appropriate reparation.589
544. The Court has applied this approach in respect of both environmental harm and harm
to individuals in Armed Activities. In respect of environmental harm, the Court
recognised that “wildlife is often subject to less social and technical monitoring than
human beings or commercial goods” and, therefore, even though “the available
evidence [was] not sufficient to determine a reasonably precise or even an approximate
number of animal deaths”, there was “a significant amount of damage to fauna” for
which Uganda was liable to make reparations.590 Similarly, as regards harm to
individuals, “while the available evidence [was] not sufficient to determine a
585 See, sub-sections II.B and II.C, above; see also, IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation
and Vulnerability (Working Group II), Summary for Policymakers (available here), para. B.1.
586 IPCC, Sixth Assessment Report, 2022, Impacts, Adaptation and Vulnerability (Working Group II) Summary
for Policymakers (available here). See also, sub-sections II.B and II.C, above.
587 IPCC, Sixth Assessment Report, 2023, Synthesis Report, Summary for Policymakers (available here), p. 15.
588 Armed Activities (Reparations), pp. 51-52, para. 106 and p. 125, para. 360; Certain Activities (Compensation),
pp. 26-27, para. 35.
589 Armed Activities (Reparations), p. 57, para. 126 (and see also, p. 56, para. 124, acknowledging that the
standard of proof may be lower in the reparations phase than in the establishment of responsibility phase).
590 Armed Activities (Reparations), p. 125, para. 359.
160
reasonably precise or even an approximate number of civilian lives lost that [were]
attributable to Uganda, it [was] nevertheless possible to identify a range of possibilities
with respect of the number of such civilian lives lost” for which Uganda was liable to
make reparations.591
ii. Causation
545. As regards the causal relationship between the wrongful conduct and the injury
sustained, the standard of causation required by the Court is that of a “sufficiently direct
and certain casual nexus between the wrongful act … and the injury suffered”.592 It is
important to note, however, that “the causal nexus required may vary depending on the
primary rule violated and the nature and extent of the injury”.593
546. As a matter of general causation, the science is undeniably clear: anthropogenic GHG
emissions cause global warming which in turn causes the specific types of harm to the
environment and human populations identified in Section 0. The IPCC has even
established the factual causative link between States’ failure to act diligently to prevent
significant harm to the global climate system and particular types of harm that have
resulted therefrom.
547. Specific causation between the wrongful act and the particular injury suffered in a given
situation will have to be assessed on a case-by-case basis. In this context, the Court has
acknowledged, as regards environmental damage, that “the state of science regarding
591 Armed Activities (Reparations), p. 71, para. 166. See also, p. 76, para. 181 as regards injuries to individuals
(“impossible to determine, even approximately, the number of persons injured as to whom Uganda owes
reparation. The Court can only find that a significant number of such injures occurred and that local patterns
can be detected”), and p. 88, para. 223 as regards displacement (“does not establish a sufficiently certain
number of displaced persons for whom compensation could be awarded separately. The evidence does,
however, indicate a range of possibilities resulting from substantiated estimates. The Court is convinced that
Uganda owes reparation in relation to a significant number of displaced persons”).
592 Armed Activities (Reparations), p. 48, para. 93 (and cases cited therein).
593 Armed Activities (Reparations), p. 48, para. 93. In Armed Activities, for example, the Court considered that
Uganda had failed in its “duty of vigilance” to prevent violations of human rights and humanitarian law in
occupied Ituri and, accordingly, adopted a presumption of causation between any injuries suffered in Ituri and
Uganda’s breaches: “it is for Uganda to establish, in this phase of the proceedings, that a particular injury
alleged by the DRC in Ituri was not caused by Uganda’s failure to meet its obligations as an occupying power.
In the absence of evidence to that effect, it may be concluded that Uganda owes reparation in relation to such
injury” (pp. 44-45, para. 78 and see also, pp. 48-49, para. 95).
161
the casual link between the wrongful act and the damage may be uncertain” but that
will not preclude the existence of a duty to make reparation.594
548. The Court has also expressly recognised that damage can arise from several concurrent
causes, including the conduct of more than one actor,595 but “the fact that damage was
the result of concurrent causes is not sufficient to exempt [a responsible State] from any
obligation to make reparations.”596 This approach grounds a State’s duty to make
reparation in its contribution to the injury suffered. Such an approach is consistent with
the long-standing view of international courts and tribunals, including in Trail Smelter
(where the injury was only partially caused by air pollution originating at the relevant
smelter)597 and Corfu Channel (where the injury to British ships was caused both by the
laying of the mines by a third State and Albania’s failure to warn of their presence).598
The approach is also consistent with the view of the ILC, and applies even where the
concurrent causes are other natural events or lawful activities.599
594 Certain Activities (Compensation), p. 26, para. 34; Armed Activities (Reparations), pp. 122-123, para. 349.
See also, the lack of certainty and reliance on circumstantial evidence in Corfu Channel, pp. 19 and 22-23. See
also, Trail Smelter, p. 1925 (“[t]he difference between probable yield in the absence of any fumigation and
actual crop yield … is necessarily a somewhat uncertain amount, incapable of absolute proof”).
595 Armed Activities (Reparations), p. 48, para. 94 and pp. 122-123, para. 349; Certain Activities (Compensation),
p. 26, para. 34.
596 Armed Activities (Reparations), p. 49, para. 97 (emphasis added).
597 Trail Smelter, pp. 1923-1924.
598 Corfu Channel, pp. 17-18 and 22-23.
599 ILC, Articles on State Responsibility, Article 31, commentary paras. 12-13 (where, “in such cases, the injury
in question was effectively caused by a combination of factors, only one of which is to be ascribed to the
responsible State, international practice and the decisions of tribunals do not support the reduction or
attenuation of reparation for concurrent causes, except in cases of contributory fault. In the Corfu Channel
case, for example, the United Kingdom recovered the full amount of its claim against Albania based on the
latter’s wrongful failure to warn of the mines even though Albania had not itself laid the mines. Such a result
should follow a fortiori in cases where the concurrent cause is not the act of another State … but of private
individuals, or some natural event such as a flood. … [U]nless some part of the injury can be shown to be
severable in causal terms from that attributed to the responsible State, the latter is held responsible for all the
consequences, not being too remote, of its wrongful conduct”). See also, footnote 471 to para. 12 of the
commentary, explaining that this “is consistent with the way in which these issues are generally dealt with in
national law.” That a responsible State will be liable for all the consequences of its wrongful conduct that are
not too remote captures what in some domestic systems is known as the “egg shell skull” rule or the rule that
the tortfeasor takes its victim as it finds them. In the present context, it means that although the environment
might already be fragile as a result of other factors, that does not reduce any liability to make reparation owed
by a responsible State whose wrongful conduct triggered harm that might not have been so significant had the
environment not been fragile.
162
549. The basis of the obligation to make reparation is, therefore the existence, not the extent,
of contribution to the injury.600 The extent of contribution is a subsequent question
relevant to the apportionment or allocation of liability for compensation between
responsible States. Indeed, the Court has recognised that principles exist for dealing
with this subsequent step of apportioning liability to pay compensation between
responsible States, as addressed below.
550. Although responsible States are bound to make reparation for injury caused by their
own conduct, that does not exclude the liability of a State to make reparations in respect
of harm caused by the conduct of private actors committed in its territory (or an area
over which it exercises effective control). Where the State has failed in its obligation
of due diligence to prevent such conduct by private actors, the harm caused by the
State’s own failure will be the same as the harm caused by the conduct of the private
actors.601 This was recognised by the Court in respect of both harm to the environment
and to individuals in Armed Activities. In that case, the Court found that Uganda was
internationally responsible for failing to comply with its due diligence obligations as an
occupying Power in Ituri602 in respect of (i) “all acts of looting, plundering or
exploitation of natural resources in the occupied territory, which includes damage to
wildlife”;603 and (ii) harm to individuals including loss of life, physical injuries and
displacement.604 The Court held that Uganda owed reparations for such damage, even
600 In this connection, suggestions have been made that victim States should not bear the burden of proving which
State caused which particular damage for the purposes of apportionment, and that a reversal of the burden of
proof is appropriate. See, e.g., Verheyen, Climate Change Damage and International Law (Martinus Nijhoff,
2005), pp. 255-256.
601 This is an example of the broader rule that States must act diligently not to allow their territory (or territory
subject to their effective control) to be used for the commission of acts contrary to the rights of other States.
See, Corfu Channel, in which Albania was held to be responsible “for the explosions which occurred … in
Albanian waters, and for the damage and loss of human life that resulted therefrom” in circumstances where
Albania did not lay the mines but where it had, at a minimum, failed to warn nearby British ships of the
presence of the mines (see, pp. 22-23 and 36).
602 The relevant obligation breached was contained in the Regulations Respecting the Laws and Customs of War
on Land annexed to the Fourth Hague Convention of 18 October 1907, Article 43, which obliges occupying
powers to “take all the measures in [their] power to restore, and ensure, as far as possible, public order and
safety”.
603 Armed Activities (Reparations), p. 125, para. 359 (emphasis added).
604 Armed Activities (Reparations), pp. 64-65, para. 149 (loss of life); p. 73, para. 173 (injuries to persons); p. 85,
para. 214 (displacement) and p. 89, para. 226 (general conclusion). See also, footnote 601 above as regards
the finding in Corfu Channel as regards loss of human life.
163
where the relevant acts were carried out by private persons or armed groups other the
Ugandan armed forces.605
551. This is significant in respect of anthropogenic GHG emissions, which are largely
emitted by private actors rather than the State itself. In circumstances where a State
fails to meet its obligations of due diligence in adequately regulating private actor
emissions, it will be liable to make full reparation for the harm caused by such
emissions.
c. Forms of reparation
552. Full reparation for injury caused by an internationally wrongful act takes the form of
one or a combination of (i) restitution, (ii) compensation in respect of damage that
cannot be made good by restitution and (iii) satisfaction in respect of injury that cannot
be made good by either restitution or compensation.606 The particular form of reparation
will depend on the injury suffered and the nature of the wrongful act which caused it.607
i. Restitution
553. Restitution – that is, re-establishing the situation which existed before the wrongful act
was committed – is the primary form of reparation required of the responsible State.608
Where, however, restitution is materially impossible or a burden out of all proportion
to the benefit deriving from it, then compensation and/or satisfaction will be the
appropriate forms of reparation.609
554. In the vast majority of cases involving significant environmental harm, restitution in
any meaningful sense is likely to be materially impossible owing to the very nature of
605 See, in particular, Armed Activities (Reparations), pp. 64-65, para. 149 (loss of life); p. 73, para. 173 (injuries
to persons); p. 85, para. 214 (displacement), pp. 125-126, paras. 359 and 361-362 (damage to wildlife). See
similarly, pp. 121-123, paras. 345-350 (biodiversity and habitat loss through deforestation, but ultimately
finding no evidence had been provided to assess damage). On Uganda’s liability to make reparation for “all
[relevant] acts” in the occupied territory, see, pp. 44-45, paras. 78-79 and p. 104, para. 275.
606 ILC, Articles on State Responsibility, Articles 34-37.
607 Pulp Mills, p. 104, para. 274; Avena and Other Mexican Nationals (Mexico v. United States of America),
Judgment, I.C.J. Reports 2004 (I), p. 59, para. 119.
608 ILC, Articles on State Responsibility, Article 35.
609 ILC, Articles on State Responsibility, Article 35; Pulp Mills, pp. 103-104, para. 273, and cases cited therein.
164
often irreversible environmental damage.610 Moreover, any active restoration efforts to
rehabilitate particular areas of the environment to their former condition that are
possible are best undertaken by the State having sovereignty over the area where the
harm occurred, rather than by the responsible State.611 These are reasons militating in
favour of compensation rather than restitution in cases of environmental harm.
ii. Compensation
555. The two key types of damage that will result from the harms identified in sub-section
II.C are damage to the environment and damage to human populations.
556. The Court has confirmed that environmental damage is compensable under
international law, and that compensation will be due for both:612
(a) damage caused to the environment, in and of itself – which can include
indemnification for the impairment or loss of environmental goods and services
in the period prior to recovery613 (including, for example, biodiversity loss614
and damage to wildlife in the form of animal deaths615); and
(b) expenses incurred by an injured State as a consequence of such damage – which
has, in one case involving the rehabilitation of protected wetlands, included
payment for “active restoration measures” necessary to return the environment
to its prior condition.616
557. In many situations involving climate-change induced damage, it will neither be possible
for an affected environmental area or feature to naturally restore itself to its previous
position, nor for “active restoration measures” achieve that result. In such cases, injured
610 See, e.g., Gabčikovo-Nagymaros, p. 78, para. 140 (recognising the “the often irreversible character of damage
to the environment and of the limitations inherent in the very mechanism of reparation of this type of damage”).
611 See, e.g., Certain Activities (Compensation), pp. 28-29, para. 43.
612 Certain Activities (Compensation), p. 28, para. 41. See also, Armed Activities (Reparations), p. 122, para. 348.
See also, ILC, Articles on State Responsibility, Article 36.
613 Certain Activities (Compensation), p. 28, para. 42 (and on “biodiversity services … in terms of habitat and
nursery services” see, p. 35, paras. 70-71 and p. 36, para. 75).
614 Certain Activities (Compensation), p. 35, paras. 70-71 and p. 36, para. 75 (“biodiversity services … in terms
of habitat and nursery services”); Armed Activities (Reparations), pp. 121-123, paras. 345-350 (“damage done
to biodiversity and the habitats of animal species” through deforestation, but ultimate finding that insufficient
evidence had been submitted).
615 Armed Activities (Reparations), pp. 125-126, paras. 359-363.
616 Certain Activities (Compensation), pp. 28-29, para. 43.
165
States will be forced to undertake adaptation measures in order to manage and mitigate
the effects of the damage caused by the responsible State/s.617 Such adaptation costs
fall squarely within the compensable category recognised by the Court of “expenses
incurred by an injured State as a consequence of [] damage” caused to the environment
by an internationally wrongful act.618 Such adaptation costs are also a specific instance
of the more general category, recognised by the ILC as being “well established”,
namely “incidental expenses” which “are compensable if they were reasonably incurred
to repair damage and otherwise mitigate loss arising from the breach.”619
558. It is therefore a straightforward application of international law principles on
compensation that responsible States are obliged to compensate injured States for
reasonably incurred adaptation measures.620
559. That responsible States should foot the bill for such adaptation measures is particularly
important in respect of States such as Antigua and Barbuda, which have made no
appreciable emissions contribute to climate change yet will require considerable and
far-reaching adaptation measures. As noted above, the effects of climate change
threatens economic activities that generate 80.4 percent of Antigua and Barbuda’s
GDP.621 Adaptation measures to mitigate such macroeconomic harm would be
recoverable,622 and may include the cost incurred in offering financial incentives for the
development of new income-generating industries and training to re-skill workers in
new professions.
560. As regards quantification of environmental harm, the Court has recognised that
“international law does not prescribe any specific method of valuation for the purposes
617 They may be obliged to do so by specific adaptation obligations (see, sub-section III.B.3, above) or in practice
forced to do so in order to prevent non-recovery of compensation for damage that could have been mitigated:
Gabčíkovo-Nagymaros, p. 55, para. 80; ILC, Articles on State Responsibility, commentary para. 11 to
Article 31.
618 Certain Activities (Compensation), p. 28, para. 41. See also, Armed Activities (Reparations), p. 122, para. 348.
619 ILC, Articles on State Responsibility, commentary para. 34 to Article 36, and footnote 579, referring to
jurisprudence from the UN Compensation Commission and the Iran-United States Claims Tribunal.
620 This is in addition to the specific obligations to assist developing States to meet adaptation costs: see, subsection
III.B.3, above.
621 See, para. 432, above.
622 Macroeconomic harm to a State’s economy may, in principle, also be independently compensable where the
existence of the injury and sufficient causal nexus are established, as the Court appears to have accepted in
Armed Activities (Reparations), pp. 127-131, paras. 367-384.
166
of compensation for environmental damage” and that it will take into account methods
that offer “a reasonable basis for valuation”, having regard to the “specific
circumstances and characteristics of each case”.623 This approach has a long pedigree,
as recognised by the Court in Certain Activities (Compensation), quoting Trail Smelter
approvingly:
Where the tort itself is of such a nature as to preclude the
ascertainment of the amount of damages with certainty, it would
be a perversion of fundamental principles of justice to deny all
relief to the injured person, and thereby relieve the wrongdoer
from making any amend for his acts. In such case, while the
damages may not be determined by mere speculation or guess, it
will be enough if the evidence show[s] the extent of the damages
as a matter of just and reasonable inference, although the result
be only approximate.624
561. Accordingly, the Court has in previous cases relied on estimates and approximations
derived from reliable data and adopted approaches that have valued various types of
environmental harm together in an overall or global manner.625
562. A similar approach has been taken to the quantification of harm to individuals – a longestablished
head of compensable damage.626 This includes material injury, such as loss
of personal property and professional earnings, and non-material (moral) injury, such
as psychological harm, “distress, suffering … and changes of a non-pecuniary nature
in the person’s everyday life”,627 as well as interferences with home and private life.628
Such heads of damage clearly encompasses the harm occasioned by, for example, being
623 Certain Activities (Compensation), p. 31, para. 52. See also, Armed Activities (Reparations), p. 106, para. 281
(“the Court will draw its conclusions on the basis of the evidence that it finds reliable in order to determine
the damage caused by Uganda to Congolese natural resources and the compensation to be awarded”).
624 Certain Activities (Compensation), p. 27, para. 35, quoting Trail Smelter, p. 1920.
625 Certain Activities (Compensation), pp. 37-39, paras. 78-87 (adopting an “overall valuation” approach); Armed
Activities (Reparations), p. 127, para. 366 (adopting a global sum for various forms of damage to natural
resources, but see also, p. 127, para. 365 noting the “exceptional circumstances of the present case”).
626 The Court has awarded compensation for harm to individuals in Corfu Channel; see also, Ahmadou Sadio
Diallo (Republic of Guinea v. Democratic Republic of the Congo), Compensation, Judgment, I.C.J. Reports
2012 (I) (hereinafter “Diallo (Compensation)”), pp. 333-344, paras. 18-57; and Armed Activities
(Reparations), pp. 137-138, para. 409(a)-(b).
627 Diallo (Compensation), p. 333, para. 18, quoting Gutiérrez‑Soler v. Colombia, Judgment of 12 September
2005 (merits, reparations and costs), IACHR, Series C, No. 132, para. 82; Armed Activities (Reparations),
p. 70, para. 164.
628 ILC, Articles on State Responsibility, commentary para. 16 to Article 36. Non-material injury to States
(affronts to dignity for example) are usually dealt with by satisfaction.
167
permanently displaced or forced to leave one’s way of life as a result of climate-change
induced rising sea levels, extreme weather events, salination of water aquifers or
decreased biodiversity on which coastal communities are dependent. The Court has
repeatedly recognised that non-material (moral) injury can be established without
specific evidence, and the quantification of compensation for such injury necessarily
rests on equitable considerations.629
iii. Satisfaction
563. Where restitution and compensation do not fully remedy the harm suffered, satisfaction
will be required. The possible scope of satisfaction is broad. It may consist of any
“appropriate modality” and will vary depending on the circumstances of the case.630 An
important form of satisfaction is a declaration by a court or tribunal that a State is in
breach of its obligations.631 Such a declaration will be particularly important where the
breach has occurred but material damage, for example to the climate system or other
parts of the environment, or to humans, has not yet materialised and thus no right to
compensation has yet arisen. In such cases, a declaratory judgment will be an
invaluable tool for States, particularly SIDS, to encourage the responsible State to
comply with its obligations and alter its behaviour. Other forms of satisfaction may
include the creation of a fund to manage compensation payments in the interests of
beneficiaries or for other purposes that are not strictly compensatory, or the award of
symbolic damages for non-pecuniary injury.632
3. The invocation of State responsibility
564. The second question in the UN General Assembly’s request asks the Court to identify
“the legal consequences” for States where they have breached the obligations that are
the subject of the first question, with respect to States, including, in particular, SIDS
(sub-section(a)), and peoples and individuals of the present and future generations (subsection
(b)). Antigua and Barbuda first addresses the invocation of responsibility
629 Diallo (Compensation), pp. 333-335, paras. 18, 21 and 24; Armed Activities (Reparations), p. 70, para. 124.
630 ILC, Articles on State Responsibility, Article 37(2) and commentary para. 5.
631 ILC, Articles on State Responsibility, Article 37, commentary para. 6; Corfu Channel, pp. 35-36.
632 ILC, Articles on State Responsibility, Article 37(2) and commentary para. 5; Armed Activities (Reparations),
p. 133, para. 391.
168
towards States, and then turns to the invocation of responsibility towards peoples and
individuals of the present and future generations.
a. Invocation of responsibility towards States
565. Below, Antigua and Barbuda provides an overview of the customary rules concerning
the invocation of responsibility of a State towards other States (sub-section (i)). Next,
Antigua and Barbuda elaborates on the customary rules that apply in circumstances,
like climate change, where there is a plurality of responsible and injured States (subsection
(ii)).
i. Requirements for invocation of responsibility by a State
566. A State’s responsibility can be invoked, (1) either by an injured State to whom
obligations are owed, or (2) by a non-injured State on the basis of erga omnes or erga
omnes partes character of the relevant obligations. Reparations can only be claimed
by, or for the benefit of, injured State. Antigua and Barbuda discusses each type of
potential invocation in turn.
(1) Invocation by an injured State
567. Article 42 of the Articles on State Responsibility identifies the circumstances under
which an injured State may invoke State responsibility. Under this provision, the
injured State may invoke the responsibility of another State, if (i) the obligation
breached is owed to that State individually, or (ii) the obligation is owed to a broader
group of States including the invoking State, and the breach specifically affects the
invoking State.633
568. That is, the following conditions need to be met for an injured State to invoke
responsibility: (i) an obligation being owed towards the invoking State (either
individually or as part of a collective), (ii) the breach of that obligation, and (iii) the
injury suffered by the invoking State being a result of that breach.
569. As discussed above, the norms relevant to these proceedings are owed to the
international community as a whole or to a group of States including SIDS like Antigua
and Barbuda. These include obligations under customary international law on the
633 See, Barcelona Traction, Light and Power Company, Limited, Judgment, I.C.J. Reports 1970 (hereinafter
“Barcelona Traction”), p. 32, para. 33.
169
prevention of harm to the environment, obligations under human rights treaties,
obligations under the UNCLOS, and obligations under the international climate change
regime. In respect of global environmental harm resulting from these norms, all States
are injured, although some are more injured or specially affected than others, such as
Antigua and Barbuda, and other SIDS.634 As such, SIDS like Antigua and Barbuda
would be in a position, in the appropriate context, to invoke responsibility of other
States in respect of these breaches. In this context, Antigua and Barbuda finds it
apposite that the ILC illustrates the concepts of “injured” and “specially affected” States
using the example of coastal States whose territory is affected by pollution of the marine
environment.635
(2) Invocation by a non-injured State
570. Article 48 of the Articles on State Responsibility sets out certain circumstances in which
responsibility may be invoked other than by an injured State.636 These are instances
where the obligation breached is owed to a group of States including the invoking State
and is established for the protection of a collective interest (obligations erga omnes
partes), or where the obligation breached is owed to international community as a
whole (obligations erga omnes).637 To be clear, a State invoking responsibility under
Article 48 need not demonstrate that it suffered injury, or that is specially affected.638
Moreover, the fact that a State or a group of States has been injured or is specially
affected does not preclude another State from invoking responsibility under this Article.
571. In this context, the obligations discussed in Section III are of an erga omnes partes or
erga omnes character. These include obligations under customary international law on
the prevention of harm to the environment, obligations under human rights treaties,
634 See, sub-section II.C, above.
635 ILC, Articles on State Responsibility, commentary on Articles 42 and 48.
636 On the Court’s confirmation of the rule reflected in Article 48, see Application of the Convention on the
Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar), Preliminary Objections,
Judgment, I.C.J. Reports 2022 (hereinafter “The Gambia v. Myanmar”), pp. 515-518, paras. 106-114;
Questions relating to the Obligation to Prosecute or Extradite (Belgium v. Senegal), Judgment, I.C.J. Reports
2012 (II) (hereinafter “Belgium v. Senegal”), pp. 449-450, paras. 68-70; Barcelona Traction, p. 32, para. 33.
See also the absence of any question of standing in Whaling in the Antarctic.
637 Belgium v. Senegal, pp. 449-450, paras. 68-70; The Gambia v. Myanmar, pp. 515-518, paras. 108-114.
638 See, the Court’s rejection of Myanmar’s argument to this effect: The Gambia v. Myanmar, pp. 511-518,
paras. 93-114. See also, Belgium v. Senegal, para. 104; Reservations to the Convention on the Prevention and
Punishment of the Crime of Genocide, I.C.J Reports 1951, p. 23.
170
obligations under the UNCLOS, and obligations under the international climate change
regime. Virtually all States can therefore invoke the responsibility of States for a breach
of these obligations. Any reparations sought in such proceedings must, however, be for
the benefit of injured States (which would include SIDS) alone.639
ii. A plurality of injured and responsible States
572. A State’s right to invoke State responsibility, on the bases discussed in the previous
sub-section, is not prejudiced in circumstances where there are multiple injured States,
or multiple responsible States. The customary rules relating to multiple injured States
and multiple responsible States are as follows:
(a) Article 46 of the Articles on State Responsibility addresses circumstances in
which an internationally wrongful act injures multiple States. Under that
Article, each injured State has an independent right to invoke the responsibility
of the State engaging in the wrongful conduct.
(b) Article 47 sets out the rules for circumstances where multiple States are
responsible for the same internationally wrongful act. Under that Article,
responsibility may independently be invoked against each of them, subject to
the rule against double recovery. Also, Article 47(2)(b) clarifies that invocation
of responsibility of one responsible State is without prejudice to the right to have
recourse against any other responsible State.
573. These rules are particularly relevant in the climate change context, since the conduct of
multiple States has contributed to violations of the norms discussed in Section III
above, and multiple States are injured by these violations. Reading Articles 46 and 47
together, any injured State or any group of injured States has the right to invoke the
responsibility of any responsible State or any group of responsible States.
574. These rules confirm that the existence of a plurality of responsible and/or injured States
does not negate either the existence of State responsibility or that the content of such
responsibility includes a duty to make reparations. Rather, a plurality of responsible
States is relevant to the issue of apportionment of quantum. In this context, the Court
639 ILC, Articles on State Responsibility, Article 48(2)(b).
171
has expressly recognised that relevant principles exist to govern such apportionment.
In Armed Activities, the Court stated:
in certain situations in which multiple causes attributable to two
or more actors have resulted in injury, a single actor may be
required to make full reparations for the damage suffered … In
other situations, in which the conduct of multiple actors has
given rise to injury, responsibility for part of such injury should
instead be allocated among those actors …640
575. The Court went on in that case to consider whether sufficient evidence had been
adduced to enable it to apportion to Uganda a specific share of the damage caused by
Ugandan and Rwandan armed forces (in circumstances where Rwanda was not before
the Court). Where the limited evidence available did not allow such apportionment,
that did not prevent the Court from awarding reparations: it found Uganda liable to
make reparations on the basis of a total sum.641 This is consistent with the principle that
the duty to make reparations is based on the existence, and not the extent, of the
contribution to the injury.
576. This principle is crucial in ensuring that victim States are not left without a remedy in
situations involving a number of States that are concurrently responsible. It is of
particular importance in the context of climate change, where responsible States may
attempt to pass the blame as amongst themselves in an effort to evade responsibility,
which the approach in Armed Activities confirms is impermissible.
577. Further, reparations are intended to wipe out the consequences of the breach to the
fullest extent possible,642 and “as far as possible, to benefit all those who suffered injury
resulting from internationally wrongful acts”.643 To these ends, any reparations made
available to a group of injured States collectively must be apportioned proportionate to
the injury suffered. Further, as noted above, the fact that reparations have been
640 Armed Activities (Reparation), pp. 49-50, para. 98.
641 See, Armed Activities (Reparation), p. 74, para. 177 and p. 76, para. 181 (injuries to persons); pp. 87-88,
para. 221 (displacement), p. 96, para. 253 (damage to property). The Court had rejected a Monetary Gold
objection by Uganda that Rwanda was an indispensable third party: Armed Activities on the Territory of the
Congo (Democratic Republic of the Congo v. Uganda), Judgment, I.C.J. Reports 2005, pp. 236-238, paras. 198
and 203-204.
642 Chorzów Factory (Merits), p. 47.
643 Armed Activities (Reparation), p. 50, para. 102, citing Diallo (Compensation), p. 344, para. 57.
172
provided to one injured State or one group of injured States does not preclude another
injured State or group of injured States from pursuing reparations owed to them.
578. In the climate change context, there is an additional factor to consider in that the injury
from climate change is universal – there are States which are both responsible and
injured. Where the context demands, the rule in Article 39 of the Articles on State
Responsibility concerning the contribution of the injured State to the injury should be
applied. Under that rule, “[i]n the determination of reparation, account shall be taken
of the contribution to the injury by wilful or negligent action or omission of the injured
State or any person or entity in relation to whom reparation is sought”.644 This rule does
no more than reflect the ordinarily principle that the responsible State shall make full
reparation for the injury that flows from its own wrong; but where part of the damage
flows from the injured State’s conduct, that must be taken into account.645 SIDS like
Antigua and Barbuda, which have made negligible historical contribution to the injury
from climate change, have not contributed to causing the environmental harm that they
are and will continue to suffer. Nor have they violated any of the primary rules
discussed in Section III, in this regard. Thus, where SIDS such as Antigua and Barbuda
seek reparation as a result of internationally wrongful acts in the climate change
context, the rule in Article 39 has no application.
b. The responsibility owed with respect to peoples and individuals
of present and future generations
579. The second question also asks what legal consequences are owed with respect to
peoples and individuals of the present and future generations adversely affected by
climate change.
580. All people and individuals of present and future generations are beneficiaries of the
obligations addressed in Section III, the goals of which are the protection of the
environment and of human rights. As beneficiaries of these international obligations,
peoples and individuals may have a legal entitlement to two things.
644 ILC, Articles on State Responsibility, Article 39, and see also, commentary paras. 3-4 thereto; LaGrand
(Germany v. United States of America), Judgment, I.C.J. Reports 2001, p. 487, para. 57 and p. 508, para. 116.
645 ILC, Articles on State Responsibility, Article 39, commentary para. 2.
173
581. The first is an entitlement to invoke the responsibility of the responsible State through
treaty-based mechanisms or domestic avenues that allow for peoples and/or individuals
to bring such actions directly. Examples of such international mechanisms include the
right of individual petition under relevant treaties.646 Domestic avenues vary from State
to State, but can allow individuals and/or peoples to challenge governmental decisions
and actions that constitute breaches of international obligations addressed in
Section III.647 Such actions can include proceedings brought on behalf of future
generations and/or may involve judicial reasoning that takes into account the interests
of future generations.648
582. The second aspect of being a beneficiary of international obligations is, in principle, an
entitlement to reparations. These may be claimed by the individuals and/or peoples
directly through the mechanisms referred to in the preceding paragraph where those
avenues so allow. Reparations may also be claimed on behalf of individuals and/or
peoples in inter-State proceedings before international courts and tribunals. This is
traditionally done in diplomatic protection cases where an action is commenced in
respect of injury suffered by a State’s nationals and where compensation is awarded for
the benefit of the individuals and/or groups concerned.649
583. Reparations may also be claimed on behalf of beneficiaries in proceedings commenced
by non-injured States in respect of violations of obligations erga omnes – including
646 See, e.g., ICCPR, OP1; ICESCR, OP; CRC, OP (on a communications procedure); CEDAW, OP; CERD,
Article 14; CPRD, OP; ACHR, Article 44; ECHR, Article 34; ACHPR, Article 55.
647 See, e.g., Supreme Court of the Netherlands, Urgenda Foundation v. State of the Netherlands, 13 January
2020.
648 See, e.g., German Constitutional Court, Neubauer et al. v. Germany, 24 March 2021 (the German
Constitutional Court required Germany to increase its mitigation efforts for the benefit of future generations);
Waratah Coal Pty Ltd v. Youth Verdict Ltd & Ors (No. 6) [2022] QLC 21 (intergenerational equity and the
need to preserve the environment for future generations were key considerations in the decision of the Land
Court of Queensland to deny an application for a coal mining lease (paras. 1588, 1589, 1593 and 1603));
Supreme Court of the Philippines, Minors Oposa v. Secretary of the Department of Environmental & Natural
Resources, G.R. No. 101083, 33 ILM 173, 30 July 1993; Supreme Court of Colombia, Appeals Chamber,
Andrea Lozano Barragán and Others v. President of the Republic and Others (Future Generations v. Ministry
of the Environment et al.), STC4360-2018 A, 5 April 2018 (ruling that deforestation and resulting temperature
increases violated the rights of future generations). In Neubauer and Future Generations, the children
plaintiffs were themselves considered to be members of future generations (see Neubauer, para. 109; Future
Generations, p. 37) but the interests of future generations were also considered more broadly.
649 See, Armed Activities (Reparation), p. 50, para. 102 and p. 137, para. 408; Cyprus v. Turkey, Judgment (Just
Satisfaction), ECtHR App. No. 25781/94, 12 May 2014, para. 46 and dispositif paras. 4(c) and 5(c); Georgia
v. Russia (I), Judgment (Just Satisfaction), ECtHR App. No. 13255/07, 31 January 2019, paras. 26 and 77, and
dispositif para. 2(c).
174
those for the protection of human rights and the environment – as expressly recognised
in Article 48 of the ILC’s Articles on State Responsibility. That Article confirms that
non-injured States can claim “the performance of the obligation of reparation … in the
interest of … the beneficiaries of the obligation breached.”650 This rule has attained
customary status, as evidenced by its invocation in a series of recent cases commenced
by non-injured States.651 Moreover, in one case involving mass harm to a large number
of individuals and/or peoples, the Court has encouraged the distribution of sums
awarded in a manner that allows “adopting measures for the benefit of the affected
communities as a whole”.652
584. Finally, while the procedural avenues for individuals and peoples to invoke
responsibility are to date limited, the question of the availability of such procedural
avenues in a particular circumstance is not to be confused with the question of existence
of responsibility. “Every internationally wrongful act of a State entails the international
responsibility of that State.”653 Where the breach causes harm, the responsible State
will have an automatic obligation to make full reparation for such harm. This remains
true whether or not procedural avenues are available for the invocation of that
responsibility.
D. Application of the rules of State responsibility in the context of climate
change
585. The second question in the UN General Assembly’s request asks the Court to identify
“the legal consequences” for States where they have breached the obligations that are
650 ILC, Articles on State Responsibility, Article 48(2)(b).
651 See, Application of the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or
Punishment (Canada and the Netherlands v. Syrian Arab Republic), Joint Application Instituting Proceedings,
8 June 2023, para. 60(f) (requesting that the Court adjudge and declare that Syria must provide individual
victims full reparation, including compensation and rehabilitation); Application of the Convention on the
Prevention and Punishment of the Crime of Genocide in the Gaza Strip (South Africa v. Israel), Application
Instituting Proceedings, 29 December 2023, para. 111(2)(e) (requesting the Court to adjudge and declare
Israel’s obligation to make reparation to the Palestinian victims); Application of the Convention on the
Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar), Application Instituting
Proceedings, 11 November 2019, para. 112, fourth bullet (requesting the Court to adjudge and declare
Myanmar’s obligation to make reparation to the Rohingya). See also, mutatis mutandis, Aerial Incident of
8 January 2020 (Canada, Sweden, Ukraine and United Kingdom v. Islamic Republic of Iran), Joint
Application Instituting Proceedings, 4 July 2023, para. 41(c)(ii) (requesting an order for compensation for the
victims and their families in circumstances where the victims were not all nationals of the Applicant States).
652 Armed Activities (Reparation), p. 137, para. 408.
653 ILC, Articles on State Responsibility, Article 1.
175
the subject of the first question. As explained above, the customary international law
of State responsibility will guide such an exercise. In this sub-section, Antigua and
Barbuda applies the customary international law of State responsibility in the context
of climate change, without prejudice to the case specific considerations that may arise
in any given case where the Court is actually called upon to identify legal consequences
for a particular State in relation to particular conduct.
586. The following discussion is organised by the list of obligations Antigua and Barbuda
identified above, in discussing Question (a). For each obligation, Antigua and Barbuda
explains (i) the type of conduct that would constitute a breach of the relevant obligation
and trigger a State’s responsibility; and (ii) the content of the responsibility, in terms of
the obligations of compliance, cessation and non-repetition, and of full reparation.
587. In sub-section IV.D.1 below, Antigua and Barbuda discusses legal consequences
stemming from the violation of mitigation obligations (as identified in subsection
III.B.1, above). In sub-section IV.D.2 below, Antigua and Barbuda then
discusses the legal consequences of violation of adaptation obligations (as identified in
sub-section III.B.2, above). Finally, in sub-section IV.D.3 below, the legal
consequences arising from violations of obligations concerning financial and
technological support (as identified in sub-section III.B.3, above) are discussed.
588. Before turning to this discussion on legal consequences that arise from breach of
individual obligations, Antigua and Barbuda reiterates certain factors that apply
horizontally, in determining legal consequences arising from violation of any of these
obligations related to climate change:
589. First, virtually all States have standing to invoke the responsibility of other States in
relation to these obligations. They may do so either in their capacity as injured States,
or as members of a collective to whom erga omnes or erga omnes partes obligations
are owed. SIDS are well-placed to invoke responsibility on either basis. Reparations
can be claimed directly by injured States for their own harm, or by non-injured States
for the benefit of injured States or of the beneficiaries of the obligations breached.
590. Second, the plurality of responsible and injured States does not shield any of the
responsible States from claims or to bar any eligible State from bringing claims. The
basis of the obligation to make reparation for an internationally wrongful act is the
176
existence and not the extent of contribution to the injury. The responsibility of any State
may be invoked without prejudice to the responsibility of other States.
591. Third, in apportioning responsibility among multiple responsible States, the most
important variable is the respective shares of States to historical global GHG emissions
in breach of the relevant obligations. In undertaking any such apportionment, Antigua
and Barbuda reiterates that emissions from colonised territories during colonial periods
are to be attributed to the colonial powers, not to the formerly colonised States.
592. Fourth, any reparations which are paid collectively should be apportioned among
injured States in a fair and equitable manner. Any such apportionment should be
proportionate to the extent of harm suffered or likely to be suffered by the injured States.
In any such apportionment, uniquely vulnerable developing States – like SIDS – must
be preferred.
1. Legal consequences of violation of mitigation obligations
593. In Section III, Antigua and Barbuda identified mitigation obligations under,
respectively, the Paris Agreement, international customary law, human rights law, the
UNCLOS and trade law.654 Specifically, Antigua and Barbuda identified the following
mitigation obligations under these sources of international law:
(a) The obligation of States Parties to the Paris Agreement to “prepare,
communicate and maintain successive nationally determined contributions”,
under Article 4.2 of the Paris Agreement. This obligation includes:
(i) The obligation to prepare an NDC, as follows:
a) Using the best available scientific evidence;
b) Accelerating mitigation efforts through rapid, deep and
sustained emission reductions, reflecting the “highest possible
ambition”. Given the 1.5°C RCB, this requires, in practice, that
a State prepare an NDC to reduce, collectively, emissions by
considerably more than 43 percent by 2030, 60 percent by 2035,
654 The legal consequences of violation of obligations under trade law are not discussed in this sub-section,
because the WTO dispute settlement system establishes specific rules on the matter. In general, a violation of
WTO obligations brings a WTO Member under an obligation to achieve prospective compliance with the
relevant obligation.
177
69 percent by 2040, and 84 percent by 2050, compared with
2019 levels, and achieve net zero CO2 emissions well before
early 2050 and net zero GHG emissions well before early 2070;
c) Respecting the principle of fairness, equity and CBDR-RC. This
requires, in practice, that each State prepare its NDC which
reduces emissions according to its equitable share of the 1.5°C
RCB;
d) Providing LDCs and SIDS special dispensation to prepare and
communicate strategies, plans and actions that reflect their
“special circumstances”; while other States must prepare an
NDC that addresses this differentiation in favour of LDCs and
SIDS;
e) Taking into account the outcome of the First Global Stocktake
Decision. In light of this outcome, a State must prepare its NDC
with an increased level of ambition, in order to meet the Paris
temperature goal and prevent dangerous anthropogenic
interference with the climate system.
(ii) The obligation to communicate an NDC, including an explanation
covering the topics identified in COP Decision 4/CMA.1.
(iii) The obligation to maintain an NDC, i.e., for a State to (i) take action to
achieve its NDC, and that (ii) the action taken meets the threshold of
diligence required, namely that it constitutes all means at its disposal to
meet its NDC.
(b) The following obligations of States under customary international law:
(i) A due diligence obligation of prevention, to adopt rapid, deep and
sustained emissions reduction measures sufficient to prevent significant
environmental harm, consistent with fairness, equity and CBDR-RC.
This obligation applies in relation to a State’s past and future emissions.
a) From the time when States first became aware of the risk that
anthropogenic GHG emissions might cause significant harm to
the climate system, States were under an obligation to take
178
diligent action to prevent such harm, in light of the degree of
knowledge and risk, the level of their emissions, and the means
at their disposal.
b) Looking forward, each developed State must do its utmost, using
all the means at its disposal, to reduce its emissions, taking into
account its equitable share of the 1.5°C RCB, the most recent
scientific evidence, and the fact that anthropogenic emissions
cause significant environmental harm at levels below the 1.5°C
temperature increase. This means that each developed State has
to reduce its emissions by considerably more than the collective
targets aligned with the IPCC 1.5°C pathway. Specifically, a
developed State must do its utmost, using all the means at its
disposal, to reduce its emissions by considerably more than 43
percent by 2030, 60 percent by 2035, 69 percent by 2040, and 84
percent by 2050, compared with 2019 levels, and achieve net
zero CO2 emissions well before early 2050 and net zero GHG
emissions well before early 2070. To emit its equitable share, a
developing State may be permitted to set emission reduction
targets that are less demanding than the collective targets aligned
with the IPCC 1.5°C pathway, depending on each developing
State’s past and present emissions, level of development and
capabilities for tackling climate change.
(ii) An obligation to cooperate, especially through notification and
consultation with potentially affected States to ensure that, in setting
emissions reduction targets to minimise the impact of climate change,
the 1.5°C RCB is indeed divided equitably.
(c) The obligation of States parties to human rights treaties to adopt effective
mitigation measures: (1) reflecting their highest possible ambition and the
precautionary principle; (2) based on the best available science; and (3) based
on principle of fairness, equity and CBDR-RC. This obligation is similar to the
customary obligation of prevention, specified under (b)(i), above, in relation to
the impact of climate change on human rights.
179
(d) The obligation of States parties to the UNCLOS, under Article 194, to do their
utmost, using all the means at their disposal, to reduce emissions sufficient to
keep long-term temperatures at a level that would prevent, reduce and control
pollution of the marine environment. This obligation is similar to the customary
obligation of prevention, specified under (b)(i), above, in relation to the impact
of climate change on pollution of the marine environment. Further, UNCLOS
Parties are also under an additional obligation to abide by their commitments
under the Paris Agreement.
594. Of these, obligations (a)(iii), (b)(i), (c) and (d) require States to reduce their emissions.
These are discussed together in sub-section (a) below as “Emission Reduction
Obligations”. The other obligations ((a)(i), (a)(ii), and (b)(ii)) are discussed in subsection
(b) below as “Other Obligations”.
a. Legal Consequences Arising from Violation of Emission
Reduction Obligations
595. Several of the obligations identified above ((a)(iii), (b)(i), (c) and (d), above) require
States to reduce their anthropogenic GHG emissions. The obligations identified in
(b)(i) above apply to all States, while the other obligations apply only to States that are
party to the relevant treaties.
596. To be clear, these obligations concern not merely emissions arising from governmental
activity, but the aggregate of all GHG emissions from the territory of a State. This
includes emissions from private actors. The obligations of a State concerning emission
reductions entail a primary obligation for the State to use its territorial and jurisdictional
competences to regulate private conduct so as to achieve the requisite levels of emission
reductions. Any conduct contrary to these emission reduction obligations would be on
account of the State’s failure to do so.655 This failure, being the conduct of organs of
the State, is attributable to the State.
597. Where these obligations are breached, they trigger the following legal consequences.
598. First, as these breaches are likely to constitute continuing breaches, the State would
come under an obligation of compliance, cessation and non-repetition. To meet these
655 Armed Activities (Reparations), pp. 64-65, para. 149, p. 73, para. 173, p. 85, para. 214, pp. 125-126, paras. 359
and 361-362.
180
obligations, the State would need to cease further emissions and achieve a sufficient
reduction of emissions, so as to be no longer in violation of its obligations. Further, the
obligation of non-repetition requires the State to take measures to ensure that in the
future, its emissions remain at levels where they do not constitute violations of the
Emission Reduction Obligations.
599. Second, and equally important, the State would also be under an obligation to make full
reparations for any injury caused by its breach of the Emission Reduction Obligations.
These reparations may take different forms in different factual circumstances. These
may include, for example:
(a) Bearing the cost of restoration of the ecosystems harmed by climate change
where such restoration is possible, and where States within whose territories the
restoration measures are to be carried out consent.
(b) Where climate change necessitates adaptation action in the territories of affected
and vulnerable States or in areas beyond national jurisdiction, paying for
adaptation measures.656 This could include the costs of building climate
resistant infrastructure like sea walls, the cost of any necessary physical
modifications to the environment, or the cost of social adaptation to the
environment. Further, where the necessary adaptation measures require the
territorial State to reduce its exploitation of certain natural resources – for
example, reducing permissible catch of a species of fish – to preserve that
resource against climate change impacts, reparations would take the form of
compensating the injured State for the reduced resources.
(c) Where loss and damage from climate change impact has already occurred and
can no longer be avoided through adaptation measures, paying monetary
compensation. This obligation would extend to all forms of loss and damage
without limitation, and would include the loss of territory, loss of lives and
656 See, Certain Activities (Compensation), pp. 28-29, para. 43 (“The Court is therefore of the view that damage
to the environment, and the consequent impairment or loss of the ability of the environment to provide goods
and services, is compensable under international law. Such compensation may include indemnification for
the impairment or loss of environmental goods and services in the period prior to recovery and payment for
the restoration of the damaged environment.”). See also, paras. 567-568, above.
181
livelihood, loss of biodiversity, loss of economic resources or opportunities, and
social impacts.657
b. Legal Consequences Arising from Violation of Other
Obligations
600. The other obligations identified above ((a)(i), (a)(ii), and (b)(ii)) do not require States
to reduce their anthropogenic GHG emissions. Specifically, these obligations require
States party to the Paris Agreement to “prepare” and “communicate” an NDCs ((a)(i),
and (a)(ii), above), and all States to cooperate ((b)(ii), above).
601. First, States Parties to Paris Agreement must prepare and communicate an NDC. States
would breach these obligations, and attract responsibility, if they fail to prepare and/or
communicate an NDC or prepare and/or communicate one that is deficient in some
manner. Deficiencies may arise on account of an NDC not being based on best
available scientific evidence, not being sufficiently ambitious, not being progressive in
comparison to a previous NDC, or not being equitable in the allocation of the remaining
carbon budget (particularly, on account of failure to appropriately reflect the principle
of CBDR-RC). Further, Parties to the Paris Agreement would breach the obligation in
(a)(ii) above if they do not communicate on topics covered by the NDC, including
topics identified in COP Decision 4/CMA.1.
602. In furtherance of the obligations of compliance, cessation and non-repetition, States
would need to prepare and communicate an NDC or a suitably revised NDC, and ensure
that appropriate NDCs are prepared and communicated in the future. For example,
where a State has prepared and communicated an NDC which is inequitable on account
of failure to properly reflect the principle of CBDR-RC, the State would need to prepare
and communicate a suitably revised NDC consistent with its primary obligation in this
regard, and ensure that its future NDCs are compliant. Similarly, a State breaching the
obligation in (iii) above would be required to make the requisite communication.
603. Where the failure to prepare and communicate an NDC, or deficiencies in an NDC has
also resulted in the State not having complied with its Emission Reduction Obligations,
the legal consequences described in sub-section (a), above, would also be triggered.
657 See, footnote 656 and paras. 567-576, above.
182
604. Second, where a State fails to cooperate, the obligation of cessation and compliance
would require the State to cooperate appropriately in the future. Further, where the
failure to cooperate has caused injury to another State or to areas beyond national
jurisdiction, the obligation of full reparation – including compensation for any loss and
damage – would apply.
2. Legal consequences of violation of adaptation obligations
605. To recall, Antigua and Barbuda identified the following adaptation obligations for
States, in Section III.B.2:
(a) The obligation of State Parties to the Paris Agreement and the UNCLOS to take
effective adaptation measures, where possible in light of the special
circumstances of the territorial State, and where support and financing for
adaptation is made available.
(b) The obligation to cooperate to ensure that adaptation measures are mutually
compatible and reinforcing, and do not undermine each other.
(c) The obligation to ensure that adaptation measures adopted in the territory of one
State do not cause transboundary harm to the territories of other States, or harm
to the environment outside national jurisdictions.
606. The obligation in (a) above is conditional in nature, and is applicable where adaptation
measures are feasible and appropriate in the special circumstances of the territorial
State, and where the necessary support and financing is made available. Where these
preconditions are met, and yet the territorial State does not undertake adaptation
measures, it would be in breach of the obligation, and its responsibility would be
engaged. The obligation of compliance and cessation, in this context, would require
the territorial State to undertake the necessary and appropriate adaptation measures in
line with the best available science, so long as the preconditions continue to be met.
607. The obligations in (b) and (c) require respectively that States do not undermine
adaptation measures of other States, or cause transboundary harm, through their
adaptation measures. Where a State causes such effects through its adaptation
measures, its wrongful conduct would attract responsibility.
183
608. In these circumstances, the obligation of compliance and cessation would require the
State to halt, reverse or modify its adaptation measure to avoid these effects. Where
harm to another State or to areas beyond national jurisdiction has already materialised,
the State would be under an obligation to make full reparations by paying for restoration
of the environment where possible, or through financial compensation for any loss and
damage.
609. That said, where such a breach is occasioned by the adaptation measures of a
particularly vulnerable State, such as one of the SIDS, necessity may apply as a
circumstance precluding wrongfulness. This will need to be considered on a case
specific basis.
3. Legal consequences of violation of support obligations
610. To recall, Antigua and Barbuda identified the following support obligations for States,
in Section III.B.3.
(a) The obligation of developed State Parties to the Paris Agreement, the UNCLOS,
the CBD or the WTO Agreement to provide financial and technological support
to mitigation and adaptation needs of developing countries. Technological
support, in this context, should include, inter alia, the creation of incentives for
private institutions to transfer technology to developing countries for their
mitigation and adaptation needs.
(b) The obligation of developed State Parties to the Paris Agreement, the UNCLOS,
the CBD or the WTO Agreement to ensure that the financial and technological
support is continuously increased until it is sufficient to meet the mitigation and
adaptation needs of developing countries. With respect to financial support,
developed State Parties to the Paris Agreement or UNCLOS are under a specific
obligation to immediately deliver at least the USD 100 billion per year floor set
in the Copenhagen Accord.658
(c) The obligation of State Parties to the Paris Agreement, the UNCLOS, the CBD
or the WTO Agreement to ensure that the allocation of any financial and
technological support takes fully into account the needs and priorities, and
658 See, sub-section III.B.3, paras. 473-483, above.
184
unique vulnerabilities, of the potential recipients. In any such allocation, SIDS
and other particularly vulnerable States must receive preference.659 This is
particularly true for adaptation support, given the urgent adaptation needs faced
by SIDS and other particularly vulnerable developing countries.
611. Developed States would be in breach of these obligations, attracting responsibility, if
they fail to provide such financial and technology assistance, deliver such assistance at
levels which are insufficient to meet the mitigation and adaptation needs of developing
countries, fail to immediately deliver at least the USD 100 billion per year floor set out
in the Copenhagen Accord, or fail to allocate assistance appropriately. Failures to
allocate assistance properly would include any allocation which, on the basis of
artificial criteria like GNI per-capita, deprives SIDS of much needed and well-deserved
priority in the allocation of assistance.660
612. The obligation of compliance and cessation would require that developed States make
up the shortfall in financial and technology support immediately, and reallocate support
in a manner consistent with their obligations. The obligation of non-repetition would
require them to take measures to ensure that they do not, in the future, fail to deliver
sufficient financial and technological support or allocate it consistently with their
obligations. While the obligation of compliance and cessation falls on each developed
State, developed States may rely on existing institutional mechanisms or create new
institutional frameworks to achieve compliance with this obligation.
613. Where a breach occurs on account of improper allocation of assistance (e.g., because
they are allocated on the basis of improper criteria like GNI per-capita), the responsible
State would be under an obligation to revise any ongoing allocation, so as to cease the
wrongful conduct. The responsible State would also be required to correct the past
improper allocations retrospectively, as a form of restitution. Furthermore, the
obligation of compliance and non-repetition would require the responsible State to
correct its allocation criteria to ensure that future allocations are consistent with its
international obligations.
659 See, sub-section III.B.3, paras. 484-494, above.
660 See, sub-section III.B.3, paras. 484-494, above.
185
614. Where all or some of the requisite financial assistance is delivered with a delay, the
obligation of full reparations would require that developed States compensate the
recipients for the loss in time value of money, by way of appropriate interest.661 This
would also include circumstances where financial assistance was allocated improperly
(e.g., because they are allocated on the basis of improper criteria like GNI per-capita)
and the allocations are revised subsequently as discussed above; the responsible States
would be an under an obligation to compensate the recipient States for the loss in time
value of money, for that portion of assistance which was previously denied to them on
account of improper allocation.
615. Further, where the failure to deliver sufficient financial and technological support in a
timely manner has resulted in the recipient having further enhanced costs of mitigation
or adaptation, the developed States would be required to compensate the recipient for
these additional costs. Moreover, where the failure to deliver sufficient financial and
technological support in a timely manner has already caused irreparable loss and
damage to the territory of another State or in areas beyond national jurisdiction,
developed countries would be under an obligation to provide financial compensation
for such loss and damage.
E. Conclusion
616. States will be responsible for breaches of their obligations outlined in Section III. The
breach of those obligations automatically gives rise to immediate duties: (i) to cease
any continuing wrongful conduct and comply with extant obligations; and (ii) where
the breach has caused injury, to make full reparation for such harm. This is a
straightforward application of the customary international law rules of State
responsibility.
617. The fact that a plurality of States has contributed to causing harm does not detract from
the conclusion that such States are responsible for their breaches and must make
reparation for the harm caused thereby. Similarly, evidential uncertainty as to the
661 See, ILC, Articles on State Responsibility, Article 38(1); S.S. “Wimbledon”, 1923, P.C.I.J., Series A, No. 1,
p. 30 (awarding post-judgment interest); Armed Activities (Reparations), pp. 135-136, paras. 401-402
(awarding post-judgment interest, and recognising that “pre-judgment interest may be awarded if full
reparation for injury caused by an internationally wrongful act so requires”). See also, Diallo (Compensation),
pp. 343-344, para. 56; Certain Activities (Compensation), p. 58, paras. 154-155).
186
precise extent of injury occasioned in a particular case, or the specific causal link in
play, will not preclude a finding of responsibility and a duty to make reparations.
618. Questions of how much compensation each responsible State is liable to pay is a
question of apportionment, which arises subsequent to the establishment of
responsibility. States can and should be found responsible for, and liable to make
reparation in respect of, breaches of international law that contribute to anthropogenic
GHG emissions which is causing significant harm to the climate system and other parts
the environment.
619. The international community faces catastrophic consequences if meaningful action on
climate change is not taken immediately. The regime of State responsibility has a vital
role to play in facilitating authoritative declarations by international courts on the
obligations and responsibilities of States which will undoubtedly have an influential
role in modifying of State behaviour for the benefit of the planet as a whole.
Zachary Phillips
Agent of Antigua and Barbuda
187
CERTIFICATION
I have the honour to certify that the annex that accompanies this Written Statement is a true
copy of the original document.
Zachary Phillips
Agent of Antigua and Barbuda
188
LIST OF ANNEXES TO THE WRITTEN STATEMENT
ANNEX
NO.
TITLE START
PAGE OF
ANNEXES
1. “Science of Climate Change and the Caribbean: Findings from the
Intergovernmental Panel on Climate Change IPCC) Sixth
Assessment Cycle (AR6)”, 5 March 2024, authored by Dr. Adelle
Thomas, Professor Michelle Mycoo, and Professor Michael
Taylor.
1
1
SCIENCE OF CLIMATE CHANGE AND THE
CARIBBEAN: FINDINGS FROM THE
INTERGOVERNMENTAL PANEL ON
CLIMATE CHANGE (IPCC) SIXTH
ASSESSMENT CYCLE (AR6)
Dr. Adelle Thomas, Climate Analytics, IPCC AR6 Lead Author, IPCC AR7 WGII Vice-Chair
Professor Michelle Mycoo, University of The West Indies, IPCC AR6 Coordinating Lead Author
Professor Michael Taylor, University of The West Indies, IPCC AR6 Coordinating Lead Author
March 5, 2024
2
TABLE OF CONTENTS
1. Executive Summary ...................................................................................................................... 4
2. Overview of the Intergovernmental Panel on Climate Change (IPCC) ...................................................6
3. Causes of Climate Change .............................................................................................................8
Historical ................................................................................................................................................ 8
Future ..................................................................................................................................................... 9
4. Observed Impacts in the Caribbean ............................................................................................... 12
Observed changes to Caribbean climate .............................................................................. 13
Temperature ......................................................................................................................................... 13
Precipitation ......................................................................................................................................... 13
Observed biophysical impacts ............................................................................................ 14
Ecosystems ........................................................................................................................................... 14
Biodiversity ........................................................................................................................................... 15
Coastal erosion...................................................................................................................................... 16
Observed socio-economic impacts ...................................................................................... 16
Freshwater stress and water security ...................................................................................................... 16
Submergence and flooding of islands and coastal areas ............................................................................17
Food security ........................................................................................................................................ 18
Tourism ................................................................................................................................................ 18
Economic impacts ................................................................................................................................. 18
Health................................................................................................................................................... 19
Cultural losses ....................................................................................................................................... 19
Settlements and infrastructure............................................................................................................... 20
Human mobility .................................................................................................................................... 20
5. Projected Risks in the Caribbean................................................................................................... 22
Projected risks for Caribbean climate .................................................................................. 24
3
Temperature ......................................................................................................................................... 24
Precipitation ......................................................................................................................................... 24
Tropical cylcones (Hurricanes) ................................................................................................................ 25
Ocean and cryosphere ........................................................................................................................... 25
Projected biophysical risks ................................................................................................. 26
Biodiversity ........................................................................................................................................... 26
Projected socio-economic risks ........................................................................................... 27
Mobility ................................................................................................................................................ 27
Freshwater stress .................................................................................................................................. 27
Agriculture and food security ................................................................................................................. 28
Tourism ................................................................................................................................................ 28
Submergence and flooding of islands and coastal areas ........................................................................... 29
Health................................................................................................................................................... 30
Limits to adaptation and adaptive capacity ............................................................................................. 31
6. Research Gaps ........................................................................................................................... 32
4
1. EXECUTIVE SUMMARY
This report provides an overview of the scientific consensus on the causes, impacts and risks of climate change for
the Caribbean region as well as important scientific research gaps. Drawing from the most recent reports of the
Intergovernmental Panel on Climate Change (IPCC), the report highlights historic responsibility for greenhouse
gases (GHG) that drive climate change, observed climatic, biophysical and socio-economic impacts of climate
change in the Caribbean and projected future risks of climate change, highlighting the importance of limiting global
average warming to 1.5C for the region.
This report draws directly from the seven reports produced in the Sixth Assessment Cycle of the IPCC. We have
extracted main findings from the IPCC reports and text is directly quoted from the reports. This provides an
objective overview of the scientific assessment of climate change causes, impacts, risks and research gaps that are
relevant to the Caribbean.
The report highlights that human activities have unequivocally caused global warming. Emissions of greenhouse
gases that have been tracked since 1850 show wide regional disparities, with small island developing states (SIDS)
across the globe contributing approximately only 0.5% of historical cumulative emissions. These emissions have
caused warming of the atmosphere of approximately 1.1C, which has resulted in widespread and rapid changes to
environments across the globe. However, SIDS, including the countries of the Caribbean, are disproportionately
affected by current impacts and future risks of climate change.
In terms of current impacts, much of the Caribbean region shows statistically significant warming of the
atmosphere and detectable decreasing trends in precipitation. The most severe drought in the region from 2013 to
2016 was strongly related to anthropogenic warming and increased the severity of the event by 17% and the spatial
extent by 7%. Small Islands of the Caribbean have experienced negative changes to terrestrial, freshwater and
ocean ecosystems with adverse implications for biodiversity. Negative impacts have been observed on many
human systems, including water and food security, health and well-being, and cities, settlements and
infrastructure. Tropical cyclones, storms, floods, droughts and coral reef damage are exacerbating existing
vulnerabilities among the population and economies of the Caribbean.
For future risks, climate change poses significant challenges for the Caribbean, threatening sustainable
development. Even if global warming is limited to 1.5C, the compounding impacts of climate change are projected
to contribute to the loss of critical natural and human systems, including threatening the habitability of some
islands and coastal communities. Some impacts may be irreversible, such as the loss of coral reefs with significant
consequences for the Caribbean including loss of coastal protection, biodiversity loss and impacts on critical
livelihoods such as tourism and fisheries. Sea level rise (SLR) has been projected to impact the terrestrial
biodiversity of low-lying islands and coastal regions via large habitat losses. Caribbean islands are among those
projected to suffer the most habitat loss with projections of between 8.7% and 49.2% of its islands entirely
submerged, respectively, from 1-m to 6-m SLR. Higher levels of global warming limit the options available for
Caribbean countries to adapt to escalating risks posed by climate change.
Limiting global warming to a specific level requires transformational change to curb cumulative carbon dioxide
emissions, reach net zero and also reduce emissions of other greenhouse gases. Future warming depends on past,
current and future emissions. Current emissions as well as future emissions planned by countries and detailed in
their submissions to the United Nations Framework Convention on Climate Change (UNFCCC) make it likely that
5
global warming will exceed 1.5C this century. Surpassing 1.5C is a critical threshold for SIDS, including in the
Caribbean, with escalating impacts of climate change resulting in limits in the ability of people and nature to adapt.
The IPCC reports also highlight that there are regional disparities in data and scientific studies, with significant gaps
in the Caribbean. Despite intensive study, many knowledge gaps remain in island-scale data availability, ecosystem
services data, vulnerability, resilience and adaptation.
In summary, the science is very clear that Caribbean SIDS have made negligible contributions to the emissions that
drive current and future climate change, that they are disproportionately affected by current impacts and future
risks of climate change and that there are significant gaps in data and scientific studies that are needed to effectively
assess and respond to climate change in the Caribbean.
6
2. OVERVIEW OF THE INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE
(IPCC)
Formed in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment
Programme (UNEP), the IPCC is mandated with providing regular assessments of the scientific evidence of climate
change, its current impacts and future risks, and strategies for adaptation and mitigation. Its core mission revolves
around furnishing governments at all levels with scientifically robust insights essential for shaping climate policies.
IPCC reports play a pivotal role as key points of reference during international climate negotiations at the United
Nations Framework Convention on Climate Change (UNFCCC). The IPCC is an organization of governments that
are members of the United Nations or WMO and currently has 195 members.
The IPCC produces assessment reports every five-seven years during assessment cycles. The most recent Sixth
Assessment Cycle concluded in 2023 and produced seven reports:
• Global Warming of 1.5C (2018)
• Climate Change and Land (2019)
• The Ocean and Cryosphere in a Changing Climate (2019)
• Climate Change 2021: The Physical Science Basis (2021)
• Climate Change 2022: Impacts, Adaptation and Vulnerability (2022)
• Climate Change 2022: Mitigation of Climate Change (2022)
• Synthesis Report: Climate Change 2023 (2023)
IPCC reports are produced with the highest level of scientific rigor. Hundreds of carefully selected scientists
volunteer their time as IPCC authors to evaluate thousands of published scientific papers and provide
comprehensive assessments of the literature. Reports are reviewed multiple times by experts and governments
around the world in order to ensure an objective assessment that reflects diversity of views and expertise. The IPCC
does not conduct its own research, rather it provides an assessment of the strength of scientific agreement in
different areas. Confidence language is used to convey this assessment of the strength of different findings and
ranges from very high confidence to low confidence, based on evaluation of underlying evidence and agreement.
Table1: Key abbreviations used in IPCC reports
CO2 Carbon dioxide
CO2-eq Carbon dioxide equivalent
ENSO El Niño-Southern Oscillation
ESL Extreme sea level
ETC Extratropical cyclone
FFI Fossil-fuel combustion and industrial
7
GHG Greenhouse gas
GMSL Global mean sea level
IAS Invasive alien species
JJA June, July, August
NDC Nationally Determined Contribution
SIDS Small island developing states
SLR Sea level rise
SST Sea surface temperature
TC Tropical cyclone
8
3. CAUSES OF CLIMATE CHANGE
HISTORICAL
Human activities, principally through emissions of greenhouse gases, have unequivocally caused global
warming, with global surface temperature reaching 1.1°C above 1850–1900 in 2011–2020. Global greenhouse
gas emissions have continued to increase over 2010–2019, with unequal historical and ongoing contributions arising
from unsustainable energy use, land use and land-use change, lifestyles and patterns of consumption and
production across regions, between and within countries, and between individuals (high confidence). Humancaused
climate change is already affecting many weather and climate extremes in every region across the globe.
This has led to widespread adverse impacts on food and water security, human health and on economies and
society and related losses and damages to nature and people (high confidence). Vulnerable communities who have
historically contributed the least to current climate change are disproportionately affected (high confidence).1
Total net anthropogenic GHG emissions have continued to rise during the period 2010–2019, as have
cumulative net CO2 emissions since 1850. Average annual GHG emissions during 2010–2019 were higher than in
any previous decade, but the rate of growth between 2010 and 2019 was lower than that between 2000 and 2009.
(high confidence)2
GHG emissions trends over 1990–2019 vary widely across regions and over time, and across different stages of
development, as shown in Figure SPM.2. Average global per capita net anthropogenic GHG emissions increased
from 7.7 to 7.8 tCO2-eq, ranging from 2.6 tCO2-eq to 19 tCO2-eq across regions. Least developed countries (LDCs)
and Small Island Developing States (SIDS) have much lower per capita emissions (1.7 tCO2-eq and 4.6 tCO2-
eq, respectively) than the global average (6.9 tCO2-eq), excluding CO2-LULUCF. (high confidence)3
Historical contributions to cumulative net anthropogenic CO2 emissions between 1850 and 2019 vary substantially
across regions in terms of total magnitude, but also in terms of contributions to CO2-FFI (1650 ± 73 GtCO2-eq) and
net CO2-LULUCF (760 ± 220 GtCO2-eq) emissions. Globally, the major share of cumulative CO2-FFI emissions is
concentrated in a few regions, while cumulative CO2-LULUCF9 emissions are concentrated in other regions. LDCs
1 IPCC, 2023: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth
Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, H. Lee and J. Romero
(eds.)]. IPCC, Geneva, Switzerland, pp. 35-115, doi: 10.59327/IPCC/AR6-9789291691647. [Synthesis Report] 2.1
2 IPCC, 2022: Summary for Policymakers [P.R. Shukla, J. Skea, A. Reisinger, R. Slade, R. Fradera, M. Pathak, A. Al
Khourdajie, M. Belkacemi, R. van Diemen, A. Hasija, G. Lisboa, S. Luz, J. Malley, D. McCollum, S. Some, P. Vyas,
(eds.)]. In: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth
Assessment Report of the Intergovernmental Panel on Climate Change [P.R. Shukla, J. Skea, R. Slade, A. Al
Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G.
Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi:
10.1017/9781009157926.001. [WGIII SPM] B.1
3 WGIII SPM B.3.1
9
contributed less than 0.4% of historical cumulative CO2-FFI emissions between 1850 and 2019, while SIDS
contributed 0.5%. (high confidence)4 [See figures on pages 10-11]
FUTURE
Limiting human-caused global warming to a specific level requires limiting cumulative CO2 emissions, reaching net
zero or net negative CO2 emissions, along with strong reductions in other GHG emissions. Future additional
warming will depend on future emissions, with total warming dominated by past and future cumulative CO₂
emissions.5
Global GHG emissions in 2030 associated with the implementation of NDCs announced prior to COP26 would
make it likely that warming will exceed 1.5°C during the 21st century and would make it harder to limit
warming below 2°C – if no additional commitments are made or actions taken.6
Global warming will continue to increase in the near term (2021–2040) mainly due to increased cumulative CO2
emissions in nearly all considered scenarios and pathways. In the near term, every region in the world is projected
to face further increases in climate hazards (medium to high confidence, depending on region and hazard), increasing
multiple risks to ecosystems and humans (very high confidence).7
4 WGIII SPM B.3.2
5 Synthesis Report Longer Report Cross Section Box.1
6 Synthesis Report Longer Report Section 2.3.1
7 Synthesis Report Longer Report Section 4.3
10
8
8 Synthesis Report Figure 2.1: The causal chain from emissions to resulting warming of the climate system.
11
9
12
4. OBSERVED IMPACTS IN THE CARIBBEAN
It is unequivocal that human influence has warmed the atmosphere, ocean and land. Widespread and rapid
changes in the atmosphere, ocean, cryosphere and biosphere have occurred10
11
9 Synthesis Report Figure 2.2: Regional GHG emissions, and the regional proportion of total cumulative
production-based CO2 emissions from 1850 to 2019
10 Synthesis Report 2.1.2
11 Synthesis Report Table 2.1: Assessment of observed changes in large-scale indicators of mean climate across
climate system components, and their attribution to human influence
13
OBSERVED CHANGES TO CARIBBEAN CLIMATE
TEMPERATURE
Significant positive trends in temperature ranging from 0.15°C per decade (over the period 1953–2010) to 0.18°C
per decade (over the period 1961–2011) are noted in the tropical western Pacific, where the significant increasing
and decreasing trends in warm and cool extremes, respectively, are also spatially homogeneous (Jones et al., 2013;
Whan et al., 2014; Wang et al., 2016). Similarly, much of the Caribbean region showed statistically significant
warming (at the 95% level) over the period 1901–2010 (P.D. Jones et al., 2016 b). Observation records in the
Caribbean region indicate a significant warming trend of 0.19°C per decade and 0.28°C per decade in daily
maximum and minimum temperatures, respectively, with statistically significant increases (at the 5% level) in
the number of warm days and warm nights during 1961–2010 (Taylor et al., 2012; Stephenson et al., 2014;
Beharry et al., 2015).12
PRECIPITATION
A weather station-based annual precipitation trend analysis over 1901–2010 in the Caribbean region indicated
some locations with detectable decreasing trends (Knutson and Zeng, 2018), which were attributable in part to
anthropogenic forcing. These include southern Cuba, the northern Bahamas, and the Windward Islands, although
significant trends were not found over the shorter periods of 1951–2010 and 1981–2010. In the Caribbean islands,
a dataset of the Palmer Drought Severity Index (PDSI) from 1950 to 2016 showed a clear drying trend in the
region (Herrera and Ault, 2017). The 2013–2016 period showed the most severe drought during the period and
was strongly related to anthropogenic warming, which would have increased the severity of the event by 17%
and its spatial extent by 7% (Herrera et al., 2018).
It is very likely that most Small Islands have warmed over the period of instrumental records. The clearest
precipitation trend is a likely decrease in JJA13 rainfall over the Caribbean since 1950. There is limited evidence
and low agreement for the cause of the observed drying trend, whether it is mainly caused by decadal-scale internal
variability or anthropogenic forcing, but it is likely that it will continue over coming decades.14
12 Gutiérrez, J.M., R.G. Jones, G.T. Narisma, L.M. Alves, M. Amjad, I.V. Gorodetskaya, M. Grose, N.A.B. Klutse, S.
Krakovska, J. Li, D. Martínez-Castro, L.O. Mearns, S.H. Mernild, T. Ngo-Duc, B. van den Hurk, and J.-H. Yoon,
2021: Atlas. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth
Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani,
S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy,
J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA, pp. 1927–2058, doi:10.1017/9781009157896.021. [WGI
Atlas].10.2
13 JJA = June, July, August
14 WGI Atlas Cross Chapter Box Atlas.2
14
15
OBSERVED BIOPHYSICAL IMPACTS
ECOSYSTEMS
16
15 WGI Atlas Cross Chapter Box Atlas.2, Table 1. Summary of observed trends for Small Island regions.
16 IPCC, 2022: Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to
the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [H.-O. Pörtner, D.C. Roberts, M.
Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B.
Rama (eds.)]. Cambridge University Press. Cambridge University Press, Cambridge, UK and New York, NY, USA,
15
BIODIVERSITY
Within the Mediterranean and Caribbean, significant losses to coastal wetlands—critical habitat for migratory
birds—has already been observed, with further significant habitat losses, redistribution and changes in quality
being projected across island systems such as the Bahamas (Caribbean) and Sardinia (Mediterranean)
(Vogiatzakis et al., 2016; Wolcott et al., 2018).17
Since 2011, the Caribbean region has witnessed unprecedented influxes of the pelagic seaweed Sargassum.
These extraordinary sargassum ‘blooms’ have resulted in mass deposition of seaweed on beaches throughout
the Lesser Antilles, with damage to coastal habitats, mortality of seagrass beds and associated corals, as well
as consequences for fisheries and tourism. This recent phenomenon has been linked to climate change as well
as the possible influence of nutrients from Amazon River floods and/or Sahara dust.18
The spread of IAS is regarded as a significant transboundary threat to the health of biodiversity and ecosystems
worldwide. The extent to which IAS (both animals and plants) successfully establish themselves at new locations in
a changing climate will be dependent on many variables, but non-climate factors such as transmission pathways,
suitability of the destination, ability to compete and adapt to new environments, and susceptibility to invasion of
host ecosystems are deemed to be critical. Modelling studies have been used to project the future ‘invisibility’ of
small island ecosystems subject to climate change and therefore to anticipate marine and terrestrial habitat
degradation in the future. Evidence suggests that hurricanes may have hastened the spread of highly invasive
Indo-Pacific lionfish (Pterois volitans) throughout the Caribbean in recent years. Two IAS, the Common Green
Iguana (Iguana iguana) and Cuban Treefrog (Osteopilus septentrionalis) were reported in the Caribbean island
of Dominica, following the passage of TC Maria in 2017.19
Rising sea temperatures are thought to increase the frequency of disease outbreaks affecting reef buildings. Of the
range of bacterial, fungal and protozoan diseases known to affect stony corals, many have explicit links to
temperature. Global projections suggest that disease is as likely to cause coral mortality as bleaching in the
coming decades at many localities, with effects occurring earlier at sites in the Caribbean compared to the
Pacific and Indian oceans. Model hindcasts suggest that climate-driven changes in SST as well as extreme
heatwave events have all played a significant role in the spread of white-band disease throughout the Caribbean.
Global food security is threatened by climate-related increases in crop pests and diseases. Black Sigatoka disease
of bananas has recently completed its invasion of Latin American and Caribbean banana-growing areas.
Infection risk has increased by a median of 44.2% across the Caribbean since the 1960s, due to increasing
canopy wetness and improving temperature conditions for the pathogen.20
3056 pp., doi:10.1017/9781009325844. [WGII] Technical Summary Figure TS.3: Observed global and regional
impacts on ecosystems and human systems attributed to climate change
17 WGII Chapter 15 Section 15.3.3.3
18 WGII Chapter 15 Table 15.5
19 WGII Chapter 15 Table 15.5
20 WGII Chapter 15 Table 15.5
16
COASTAL EROSION
Despite important knowledge gaps on coastal erosion in high tropical islands, recent studies confirmed increasing
shoreline retreat and beach loss over the past decades, mainly due to TC and ETC waves and human
disturbances (high confidence) (e.g., in the Caribbean region: Anguilla, Saint-Kitts, Nevis, Montserrat,
Dominica and Grenada (Cambers, 2009; Reguero et al., 2018)), and Pacific (Hawaii (Romine and Fletcher, 2013);
Tubuai, French Polynesia (Salmon et al., 2019)) and Indian Oceans (Anjouan, Comoros (Ratter et al., 2016).21
OBSERVED SOCIO-ECONOMIC IMPACTS
22
FRESHWATER STRESS AND WATER SECURITY
Climate change impacts on freshwater systems frequently exacerbate existing pressure, especially in locations
already experiencing water scarcity (Section 15.3.3.2 and Cross-Chapter Box INTERREG in Chapter 16; Schewe
et al., 2014; Holding et al., 2016; Karnauskas et al., 2016), making water security a key risk (KR4 in Figure 15.5) in
small islands. Small islands are usually environments where demand for resources related to socioeconomic factors
21 WGII Chapter 15 Section 15.3.3.1.2
22 WGII Technical Summary Figure TS.3 Observed global and regional impacts on ecosystems and human systems
attributed to climate change
17
such as population growth, urbanisation and tourism already place increasing pressure on limited freshwater
resources. In many small islands, water demand already exceeds supply. For example, in the Caribbean, Barbados
is utilising close to 100% of its available water resources and St. Lucia has a water supply deficit of
approximately 35% (Cashman, 2014).23
The Caribbean and Pacific regions have historically been affected by severe droughts (Peters, 2015; FAO, 2016;
Barkey and Bailey, 2017; Paeniu et al., 2017; Trotman et al., 2017; Anshuka et al., 2018) with significant physical
impacts and negative socioeconomic outcomes. Water quality is affected by drought as well as water availability.
The El Niño related 2015–1016 drought in Vanuatu led to reliance on small amounts of contaminated water left at
the bottom of household tanks (Iese et al., 2021a). The highest land disturbance percentages have coincided with
major droughts in Cuba (de Beurs et al., 2019). Drought has been shown to have an impact on rainwater
harvesting in the Pacific (Quigley et al., 2016) and Caribbean (Aladenola et al., 2016), especially in rural areas
where connections to centralised public water supply have been difficult. Increasing trends in drought are
apparent in the Caribbean (Herrera and Ault, 2017) although trends in the western Pacific are not statistically
significant (McGree et al., 2016).24
Climate change has intensified the global hydrological cycle, causing several societal impacts, which are felt
disproportionately by vulnerable people (high confidence). Human-induced climate change has affected physical
aspects of water security through increasing water scarcity and exposing more people to water-related extreme
events like floods and droughts, thereby exacerbating existing water-related vulnerabilities caused by other
socioeconomic factors (high confidence). Many of these changes in water availability and water-related hazards can
be directly attributed to anthropogenic climate change (high confidence). Water insecurity disproportionately
impacts the poor, women, children, Indigenous Peoples and the elderly in low-income countries (high confidence)
and specific marginal geographies (e.g., small island states and mountain regions). Water insecurity can contribute
to social unrest in regions where inequality is high and water governance and institutions are weak (medium
confidence).25
SUBMERGENCE AND FLOODING OF ISLANDS AND COASTAL AREAS
Recent studies confirmed that observed ESL events causing extensive flooding generally resulted from compound
effects, including the combination of SLR (Section 3.2.2.2 and Cross-Chapter Box SLR in Chapter 3) with ETCs, TCs
and tropical depressions (WGI AR6 Sections 11.7.1 and 11.7.2, Seneviratne, 2021), ENSO-related highwater levels
associated with high or spring tide and/or local human disturbances amplifying impacts (high confidence).26
Despite important knowledge gaps on coastal erosion in high tropical islands, recent studies confirmed increasing
shoreline retreat and beach loss over the past decades, mainly due to TC and ETC waves and human
23 WGII Chapter 15 Section 15.3.4.3
24 WGII Chapter 15 Section 15.3.4.3
25 WGII Technical Summary TS.B.4.1
26 WGII Chapter 15 Section 15.3.3.1.1
18
disturbances (high confidence) (e.g., in the Caribbean region: Anguilla, Saint-Kitts, Nevis, Montserrat,
Dominica and Grenada (Cambers, 2009; Reguero et al., 2018))27
FOOD SECURITY
Climate change influences food and nutritional security through its effects on food availability, quality, access and
distribution (Paterson and Lima, 2010; Thornton et al., 2014; FAO, 2016). More than 815 million people were
undernourished in 2016, and 11% of the world’s population has experienced recent decreases in food security, with
higher percentages in Africa (20%), southern Asia (14.4%) and the Caribbean (17.7%) (FAO et al., 2017).28
Climate-related extremes have affected the productivity of all agricultural and fishery sectors, with negative
consequences for food security and livelihoods (high confidence). The frequency of sudden food production losses
has increased since at least the mid20th century on land and sea (medium evidence, high agreement). The impacts
of climate-related extremes on food security, nutrition and livelihoods are particularly acute and severe for people
living in sub-Saharan Africa, Asia, small islands, Central and South America and the Arctic and small-scale food
producers globally (high confidence).29
TOURISM
Many small island economies are sustained by tourism and have invested heavily in associated infrastructure and
capacity building (Cannonier and Burke, 2018). Some rural island communities have become dependent on tourism
to the point that it would be difficult to revert to subsistence living (Lasso and Dahles, 2018). Coast-focused (beachsea)
tourism in island contexts is already being impacted by beach erosion, elevated high SST causing coral
bleaching, and associated marine-biodiversity loss, as well as more intense TCs (Tapsuwan and Rongrongmuang,
2015; Parsons et al., 2018; Wabnitz et al., 2018)30
ECONOMIC IMPACTS
The extreme events occurring today, such as storms, tropical cyclones (TC), droughts, floods and marine heat
waves (Herring et al., 2017), provide striking illustrations of the vulnerability of small island systems (high
confidence) (Section 6.8.5, Box 4.2, Box 6.1). Societal dimensions can combine with climate changes, e.g., sea level
27 WGII Chapter 15 Section 15.3.3.1.2
28 IPCC, 2018 Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above
pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the
global response to the threat of climate change, sustainable development, and efforts to eradicate poverty
[Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C.
Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor,
and T. Waterfield (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 3-24.
https://doi.org/10.1017/9781009157940.001. [SR 1.5C], Cross-Chapter Box 6
29 WGII Technical Summary TS.B.3.3
30 WGII Chapter 15 Section 15.3.4.5
19
rise, to amplify the impact of TCs, storm surge and ocean acidification in small islands contributing to loss and
damage (Moser and Hart, 2015; Noy and Edmonds, 2016). For example, Category 5 TC Pam devastated Vanuatu in
2015 with 449.4 million USD in losses for an economy with a GDP of 758 million USD (Government of Vanuatu,
2015; Handmer and Iveson, 2017). Kiribati, Papua New Guinea, Solomon Islands and Tuvalu were all impacted by
the TC Pam system (IFRC, 2018). In 2016, TC Winston caused 43 deaths in Fiji and losses of more than one third of
the GDP (Government of Fiji, 2016; Cox et al., 2018). In 2017, Hurricanes Maria and Irma swept through 15
Caribbean countries, causing major damages and casualties across numerous islands. Rebuilding in three
countries alone – Dominica, Barbuda and the British Virgin Islands – will cost an estimated 5 billion USD
(UNDP, 2017). The Post-Disaster Needs Assessment for Dominica concluded that hurricane Maria resulted in
total damages amounting to 226% of 2016 GDP (The Government of the Commonwealth of Dominica, 2017).31
HEALTH
The transport of airborne Saharan dust across the Atlantic into the Caribbean has been intensively studied. In the
West African Sahel, where drought has been persistent since the mid-1960s, analysis has shown that there have
been remarkable changes in dust emissions since the late 1940s. Variability in Sahel dust emissions may be related
not only to droughts, but also to changes in the North Atlantic Oscillation (NAO), North Atlantic SST and the
Atlantic Multidecadal Oscillation (AMO). The frequency of dust storms has been on the rise during the last decade.
Forecasts suggest that their incidence will increase further. Transboundary movement of Saharan dust into the
island regions of the Caribbean and the Mediterranean has been associated with human health problems
including asthma cases in the Caribbean, cardiovascular morbidity in Cyprus and pulmonary disease in the Cape
Verde islands.32
CULTURAL LOSSES
The unquantifiable and highly localised cultural losses resulting from climate drivers are less researched and less
acknowledged in policy than physical and economic losses (Karlsson and Hovelsrud, 2015; Thomas and Benjamin,
2018a). In the Bahamas, prolonged displacement of the entire population of Ragged Island following Hurricane
Irma (2017) highlighted the cultural losses that can result from climate-induced displacement from ancestral
homelands. Threats to identity, sense of place and community cohesion resulted from displacement, although all
were important foundational features of the Islanders’ self-initiated rehabilitation efforts and eventual return.
Nonetheless, non-economic losses were not accounted for by policy addressing displacement (Thomas and
Benjamin, 2018a). In the case of Monkey River Village in Belize, coastal erosion is threatening the community’s
cemetery. Residents place significant spiritual and emotional value on the cemetery, which serves important
community functions, and, thus, threats to it are perceived to be serious and necessary to be taken into
account in any planned response (Karlsson and Hovelsrud, 2015). A similar situation exists on Carriacou in the
West Indies where culturally and historically significant archaeological sites are being lost due to coastal
31 IPCC, 2019 IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [H.-O. Pörtner, D.C.
Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem,
J. Petzold, B. Rama, N.M. Weyer (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp.
3–35. https://doi.org/10.1017/9781009157964.001. [SROCC], CCB9
32 WGII Chapter 15. Table 15.5
20
erosion caused by a combination of sand mining and extreme climate-ocean events exacerbated by SLR
(Fitzpatrick et al., 2006).33
SETTLEMENTS AND INFRASTRUCTURE
Categories 4 and 5 TCs are severely impacting settlements and infrastructure in small islands. TC Maria in 2017
destroyed nearly all of Dominica’s infrastructure and losses per unit of GDP amounted to more than 225% of
the annual GDP (Eckstein et al., 2018). Destruction from TC Winston in 2016 amounted to more than 20% of Fiji’s
current GDP (Cox et al., 2018). Additionally, living conditions in human settlements are changing due to storm surge
which is already penetrating further inland compared with a few decades ago (IPCC, 2018, Section 3.4.4.3; Brown
et al., 2018).34
As a result of slow-onset ocean and climate changes and changes in extreme events, settlements and infrastructure
of small islands are at growing risk due to climate change in the absence of adaptation measures (high confidence).
Ocean acidification and deoxygenation, increased ocean temperatures and relative SLR are impacting marine,
coastal and terrestrial biodiversity and ecosystem services, making settlements more exposed and vulnerable to
climate-related hazards. Changes in rainfall patterns such as heavy precipitation result in annual flood events
that damage major assets and result in a loss of human life. Examples of settlements where this has occurred
are Port of Spain (Mycoo, 2014b; 2018a), Haiti (Weissenberger, 2018), Viti Levu (Brown et al., 2017; Singh-
Peterson and Iranacolaivalu, 2018), urban areas of Fiji and Kiribati (McAneney et al., 2017; Cauchi et al., 2021), Male’,
Maldives (Wadey et al., 2017), and Mahé, in the Seychelles (Etongo, 2019).35
Coastal settlements with high inequality, for example a high proportion of informal settlements, as well as deltaic
cities prone to land subsidence (e.g., Bangkok, Jakarta, Lagos, New Orleans, Mississippi, Nile, Ganges-Brahmaputra
deltas) and small island states are highly vulnerable and have experienced impacts from severe storms and
floods in addition to, or in combination with, those from accelerating sea level rise (high confidence).36
HUMAN MOBILITY
The most common climatic drivers for migration and displacement are drought, tropical storms and hurricanes,
heavy rains and floods (high confidence). Extreme climate events act as both direct drivers (e.g., destruction of
homes by tropical cyclones) and indirect drivers (e.g., rural income losses during prolonged droughts) of
involuntary migration and displacement (very high confidence). The largest absolute number of people displaced
by extreme weather each year occurs in Asia (South, Southeast and East), followed by sub-Saharan Africa, but
33 WGII Chapter 15 Section 15.3.4.7
34 WGII Chapter 15 Section 15.3.4.1
35 WGII Chapter 15 Section 15.3.4.1
36 WGII Technical Summary TS.B.8.2
21
small island states in the Caribbean and South Pacific are disproportionately affected relative to their small
population size (high confidence).37
37 WGII Technical Summary TS.B.6.1
22
5. PROJECTED RISKS IN THE CARIBBEAN
It is widely recognized that small islands are very sensitive to climate change impacts such as sea level rise, oceanic
warming, heavy precipitation, cyclones and coral bleaching (high confidence) (Nurse et al., 2014; Ourbak and
Magnan, 2017). Even at 1.5°C of global warming, the compounding impacts of changes in rainfall, temperature,
tropical cyclones and sea level are likely to be significant across multiple natural and human systems. There
are potential benefits to small island developing states (SIDS) from avoided risks at 1.5°C versus 2°C, especially
when coupled with adaptation efforts. In terms of sea level rise, by 2150, roughly 60,000 fewer people living in
SIDS will be exposed in a 1.5°C world than in a 2°C world (Rasmussen et al., 2018). Constraining global warming to
1.5°C may significantly reduce water stress (by about 25%) compared to the projected water stress at 2°C, for
example in the Caribbean region (Karnauskas et al., 2018), and may enhance the ability of SIDS to adapt (Benjamin
and Thomas, 2016). Up to 50% of the year is projected to be very warm in the Caribbean at 1.5°C, with a further
increase by up to 70 days at 2°C versus 1.5°C (Taylor et al., 2018). By limiting warming to 1.5°C instead of 2°C in
2050, risks of coastal flooding (measured as the flood amplification factors for 100-year flood events) are reduced
by 20–80% for SIDS (Rasmussen et al., 2018). A case study of Jamaica with lessons for other Caribbean SIDS
demonstrated that the difference between 1.5°C and 2°C is likely to challenge livestock thermoregulation,
resulting in persistent heat stress for livestock (Lallo et al., 2018).38
Global warming of 1.5°C is expected to prove challenging for small island developing states (SIDS) that are
already experiencing impacts associated with climate change (high confidence). At 1.5°C, compounding impacts
from interactions between climate drivers may contribute to the loss of, or change in, critical natural and human
systems (medium to high confidence). There are a number of reduced risks at 1.5°C versus 2°C, particularly when
coupled with adaptation efforts (medium to high confidence).39
SIDS are home to 65 million people (UN-OHRLLS, 2015). More than 80% of small island residents live near the coast
where flooding and coastal erosion already pose serious problems (Nurse et al., 2014) and since the IPCC 5th
Assessment Report (AR5) and the Special Report on Global Warming of 1.5ºC (SR1.5), there is consensus on
the increasing threats to island sustainability in terms of land, soils and freshwater availability. As a result,
there is growing concern that some island nations as a whole may become uninhabitable due to rising sea
levels and climate change, with implications for relocation, sovereignty and statehood (Burkett, 2011; Gerrard
and Wannier, 2013; Yamamoto and Esteban, 2014; Donner, 2015).40
Key risks for Small Islands include: Loss of terrestrial, marine and coastal biodiversity and ecosystem services- Loss
of lives and assets, risk to food security and economic disruption due to destruction of settlements and
infrastructure- Economic decline and livelihood failure of fisheries, agriculture, tourism and from biodiversity loss
from traditional agroecosystems - Reduced habitability of reef and non-reef islands leading to increased
displacement- Risk to water security in almost every small island.41 [See Figure pg. 23]
38 SR 1.5C, Section 3.5.4.9
39 SR 1.5C, Box 3.5
40 SROCC, CCB9
41 WGII Technical Summary Figure TS.4
23
42
42 WGII Chapter 15. Figure 15.5 Key risks in small islands
24
PROJECTED RISKS FOR CARIBBEAN CLIMATE
TEMPERATURE
Small Islands will very likely continue to warm this century, though at a rate less than the global average
(Figure Atlas.28), with consequent increased frequency of warm extremes for the Caribbean and western
Pacific islands, and heatwave events for the Caribbean (high confidence).43
Mean surface temperature is projected to increase in SIDS at 1.5°C of global warming (high confidence). The
Caribbean region will experience 0.5°C–1.5°C of warming compared to a 1971–2000 baseline, with the
strongest warming occurring over larger land masses (Taylor et al., 2018). Under the Representative
Concentration Pathway (RCP)2.6 scenario, the western tropical Pacific is projected to experience warming of
0.5°C–1.7°C relative to 1961–1990. Extreme temperatures will also increase, with potential for elevated impacts as
a result of comparably small natural variability (Reyer et al., 2017a). Compared to the 1971–2000 baseline, up to
50% of the year is projected to be under warm spell conditions in the Caribbean at 1.5°C, with a further increase
of up to 70 days at 2°C (Taylor et al., 2018).44
PRECIPITATION
Rainfall is very likely to decline over the Caribbean, in the annual mean and especially in JJA, with a stronger and
more coherent signal in CMIP6 compared to CMIP5 (Figure Atlas.28 and Interactive Atlas) and reductions of 20–
30% by the end of the century under high future emissions (SSP5-8.5). This JJA drying has been linked to a future
strengthening of the Caribbean low level jet (CLLJ) (Taylor et al., 2013a), a westward expansion and intensification
of the NASH, stronger low-level easterlies over the region, a southwardly-placed eastern Pacific ITCZ (Rauscher et
al., 2008), and changing dynamics due to increased greenhouse gas concentrations (very high confidence) (W. Li et
al., 2012 ). Projections from 15 GCM and two RCM experiments for 2080–2089 relative to 1970–1989 were for a
generally drier Caribbean and a robust summer drying (Karmalkar et al., 2013). More recent downscaling studies
(e.g., Taylor et al., 2018; Vichot-Llano et al., 2021a) also project a drier Caribbean and longer dry spells (Van
Meerbeeck, 2020).45
Changes in precipitation patterns, freshwater availability and drought sensitivity differ among small island regions
(medium to high confidence). In accordance with an overall drying trend, an increasing drought risk is projected
for Caribbean SIDS (Lehner et al., 2017), and moderate to extreme drought conditions are projected to be
about 9% longer on average at 2°C versus 1.5°C for islands in this region (Taylor et al., 2018).46
Projected increases in aridity and decreases in freshwater availability at 1.5°C of warming, along with additional
risks from SLR and increased wave-induced run-up, might leave several atoll islands uninhabitable (Storlazzi et al.,
43 WGI Atlas Cross Chapter Box Atlas.2
44 SR 1.5C, Box 3.5
45 WGI Atlas Cross Chapter Box Atlas.2
46 SR 1.5C, Box 3.5
25
2015; Gosling and Arnell, 2016). Changes in the availability and quality of freshwater, linked to a combination of
changes to climate drivers, may adversely impact SIDS’ economies (White and Falkland, 2010; Terry and Chui, 2012;
Holding and Allen, 2015; Donk et al., 2018). Growth-rate projections based on temperature impacts alone indicate
robust negative impacts on gross domestic product (GDP) per capita growth for SIDS (Sections 3.4.7.1, 3.4.9.1 and
3.5.4.9; Pretis et al., 2018). These impacts would be reduced considerably under 1.5°C but may be increased by
escalating risks from climate-related extreme weather events and SLR (Sections 3.4.5.3, 3.4.9.4 and 3.5.3).47
TROPICAL CYLCONES (HURRICANES)
It is likely that the proportion of major (Category 3–5) tropical cyclones (TCs) and the frequency of rapid TC
intensification events have increased over the past four decades. The average location of peak TC wind-intensity
has very likely migrated poleward in the western North Pacific Ocean since the 1940s, and TC forward translation
speed has likely slowed over the contiguous USA since 1900. It is likely that the poleward migration of TCs in the
western North Pacific and the global increase in TC intensity rates cannot be explained entirely by natural
variability. There is high confidence that average peak TC wind speeds and the proportion of Category 4–5 TCs
will increase with warming and that peak winds of the most intense TCs will increase. There is medium
confidence that the average location where TCs reach their maximum wind-intensity will migrate poleward in the
western North Pacific Ocean, while the total global frequency of TC formation will decrease or remain unchanged
with increasing global warming. {11.7.1}48
Additional regional changes in Small Islands, besides those features described in Section TS.4.3.1, include a likely
decrease in rainfall during boreal summer in the Caribbean and in some parts of the Pacific islands poleward of 20°
latitude in both the Northern and Southern Hemispheres. These drying trends will likely continue in coming
decades. Fewer but more intense tropical cyclones are projected starting from a 2°C Global Warming Level
(medium confidence). {9.6, 11.3, 11.4, 11.7, 11.9, 12.4.7, Atlas.10.2, Atlas.10.4, Cross-Chapter Box Atlas.2}49
OCEAN AND CRYOSPHERE
Ocean and cryosphere changes already impact Low-Lying Islands and Coasts (LLIC), including Small Island
Developing States (SIDS), with cascading and compounding risks. Disproportionately higher risks are
expected in the course of the 21st century. Reinforcing the findings of the IPCC Special Report on Global Warming
of 1.5°C, vulnerable human communities, especially those in coral reef environments and polar regions, may exceed
adaptation limits well before the end of this century and even in a low greenhouse gas emission pathway (high
confidence).50
47 SR 1.5C, Box 3.5
48 WGI Technical Summary Section TS2.3
49 WG1 Technical Summary Section TS4.3.2.7
50 SROCC. Technical Summary
26
Due to projected GMSL rise, ESLs that are historically rare (for example, today’s hundred-year event) will
become common by 2100 under all RCPs (high confidence). Many low-lying cities and small islands at most
latitudes will experience such events annually by 2050. Greenhouse gas (GHG) mitigation envisioned in lowemission
scenarios (e.g., RCP2.6) is expected to sharply reduce but not eliminate risk to low-lying coasts and islands
from SLR and ESL events. Low-emission scenarios lead to slower rates of SLR and allow for a wider range of
adaptation options. For the first half of the 21st century differences in ESL events among the scenarios are small,
facilitating adaptation planning.51
Extreme precipitation in small island regions is often linked to tropical storms and contributes to the climate hazard
(Khouakhi et al., 2017). Similarly, extreme sea levels for small islands, particularly in the Caribbean, are linked
to tropical cyclone occurrence (Khouakhi and Villarini, 2017). Under a 1.5°C stabilization scenario, there is a
projected decrease in the frequency of weaker tropical storms and an increase in the number of intense
cyclones (Section 3.3.6; Wehner et al., 2018a).52
PROJECTED BIOPHYSICAL RISKS
BIODIVERSITY
Even achieving emission reduction targets consistent with the ambitious goal of 1.5°C of global warming under the
Paris Agreement will result in the further loss of 70–90% of reef-building corals compared to today, with 99% of
corals being lost under warming of 2°C or more above the pre-industrial period (high confidence) (Hoegh-
Guldberg et al., 2018).53
Marine systems and associated livelihoods in SIDS face higher risks at 2°C compared to 1.5°C (medium to high
confidence). Mass coral bleaching and mortality are projected to increase because of interactions between
rising ocean temperatures, ocean acidification, and destructive waves from intensifying storms (Section 3.4.4
and 5.2.3, Box 3.4). At 1.5°C, approximately 70–90% of global coral reefs are projected to be at risk of long-term
degradation due to coral bleaching, with these values increasing to 99% at 2°C (Frieler et al., 2013; Schleussner et
al., 2016b). Higher temperatures are also related to an increase in coral disease development, leading to coral
degradation (Maynard et al., 2015). For marine fisheries, limiting warming to 1.5°C decreases the risk of species
extinction and declines in maximum catch potential, particularly for small islands in tropical oceans (Cheung et al.,
2016a).54
The majority of studies modelling geographical range changes of small island species, to even the most
optimistic 21st century climate change scenarios, imply a reduction in climate refugia (Table 15.3, Box CCP1.1).
This is due to projected strong shifts, reductions or even complete losses of climatic niches resulting from
51 SROCC. Technical Summary
52 SR 1.5C, Box 3.5
53 WGII Chapter 15. Section 15.3.3.1.3
54 SR 1.5C, Box 3.5
27
inadequate geographic space for species to track suitable climate envelopes (high confidence) (e.g., Maharaj and
New, 2013; Fortini et al., 2015; Struebig et al., 2015b). Because of the high proportion of global endemics hosted
within small and especially isolated islands, the resulting increased extinction risk of such species (up to 100%)
could lead to disproportionate losses in global biodiversity (medium to high confidence) (Harter et al., 2015;
Manes et al., 2021).55
SLR has been projected to impact the terrestrial biodiversity of lowlying islands and coastal regions via large habitat
losses both directly (e.g., submergence) and indirectly (e.g., salinity intrusion, salinization of coastal wetlands and
soil erosion) at even the 1-m scenario (medium to high confidence). However, these impacts vary depending on the
islands’ topographical differences. In a study of SLR impacts on insular biodiversity hotspots, Bellard et al.
(2013a) reported that the Caribbean islands, Sundaland and the Philippines were projected to suffer the most
habitat loss while the East Melanesian islands were projected to be less (but not minimally) affected. The most
threatened of these, the Caribbean, was projected to have between 8.7% and 49.2% of its islands entirely
submerged, respectively, from 1-m to 6-m SLR (Bellard et al., 2013a). However, many current projection studies
consider marine flooding directly and seldom incorporate other indirect impacts such as increased habitat losses
from horizontal erosion loss, increased salinity levels, tidal ranges and extreme events. These projections are
considered to be conservative, underestimating the extent of habitat loss to terrestrial biodiversity (Bellard et al.,
2013b).56
PROJECTED SOCIO-ECONOMIC RISKS
MOBILITY
Risks of impacts across sectors are projected to be higher at 1.5°C compared to the present, and will further increase
at 2°C (medium to high confidence). Projections indicate that at 1.5°C there will be increased incidents of internal
migration and displacement (Sections 3.5.5, 4.3.6 and 5.2.2; Albert et al., 2017), limited capacity to assess loss
and damage (Thomas and Benjamin, 2017) and substantial increases in the risk to critical transportation
infrastructure from marine inundation (Monioudi et al., 2018).57
FRESHWATER STRESS
Projected changes in aridity are expected to impose freshwater stress on many small islands, especially SIDS (high
confidence). These changes are congruent with drought risk projections for Caribbean SIDS (Lehner et al., 2017;
Taylor et al., 2018) and aligned with observations from the Shared Socioeconomic Pathway (SSP) 2 scenario,
where a 1°C increase in temperature (from 1.7°C to 2.7°C) could result in a 60% increase in the number of people
55 WGII Chapter 15. Section 15.3.3.3
56 WGII Chapter 15. Section 15.3.3.3
57 SR1.5 Chapter 3 Box3.5
28
projected to experience severe water resources stress from 2043 to 2071 (Schewe et al., 2014; Karnauskas et al.,
2018).58
Projected changes in aridity are expected to impose freshwater stress on many small islands, especially SIDS (high
confidence). It is estimated that with a warming of 1.5°C or less, freshwater stress on small islands would be 25%
less as compared to 2.0°C. While some island regions are projected to experience substantial freshwater decline,
an opposite trend is observed for some western Pacific and northern Indian Ocean islands. Drought risk projections
for Caribbean SIDS aligned with observations from the Shared Socioeconomic Pathway (SSP) 2 scenario
indicate that a 1°C increase in temperature (from 1.7°C to 2.7°C) could result in a 60% increase in the number
of people projected to experience severe water resources stress from 2043 to 2071. In some Pacific atolls,
freshwater resources could be significantly affected by a 0.40-m SLR. Similar impacts are anticipated for some
Caribbean countries with the worst-case scenario (RCP8.5) indicating a 0.5-m SLR by the mid-century (2046–
2065) and a 1-m SLR by the end-of-century (2081–2100). SIDS with high projected population growth rates are
expected to experience the most severe freshwater stress by 2030 under a 2°C warming threshold scenario
{15.3.3.2}59
AGRICULTURE AND FOOD SECURITY
In the Caribbean, additional warming by 0.2°–1.0°C could lead to a predominantly drier region (5–15% less
rain than present-day), a greater occurrence of droughts (Taylor et al., 2018) along with associated impacts
on agricultural production and yield in the region (Gamble et al., 2017; Hoegh-Guldberg et al., 2019; Nicolas
et al., 2020). Crop suitability modelling on several commercially important crops grown in Jamaica found that
even an increase of less than 1.5°C could result in a reduction in the range of crops that farmers may grow
(Rhiney et al., 2018).60
Climate change will increasingly add significant pressure and regionally different impacts on all components of
food systems, undermining all dimensions of food security (high confidence). Extreme weather events will increase
risks of food insecurity via spikes in food prices, reduced food diversity and reduced income for agricultural and
fishery livelihoods (high confidence), preventing achievement of the UN SDG 2 (‘Zero Hunger’) by 2030 in regions
with limited adaptive capacities, including Africa, small island states and South Asia (high confidence).61
TOURISM
The tourism sector is also affected by climate-induced changes in environmental assets critical for tourism,
including biodiversity, beaches, glaciers and other features important for environmental and cultural heritage.
Limited analyses of projected risks associated with 1.5°C versus 2°C are available (Section 3.4.4.12). A global
analysis of sea level rise (SLR) risk to 720 UNESCO Cultural World Heritage sites projected that about 47 sites might
58 WGII Chapter 15. Section 15.3.3.1.4
59 WGII Chapter 15. ES.
60 WGII Chapter 15. Section 15.3.4.4
61 WGII Technical Summary TS.C.3.3
29
be affected under 1°C of warming, with this number increasing to 110 and 136 sites under 2°C and 3°C, respectively
(Marzeion and Levermann, 2014). Similar risks to vast worldwide coastal tourism infrastructure and beach assets
remain unquantified for most major tourism destinations and small island developing states (SIDS) that
economically depend on coastal tourism. One exception is the projection that an eventual 1 m SLR could partially
or fully inundate 29% of 900 coastal resorts in 19 Caribbean countries, with a substantially higher proportion
(49–60%) vulnerable to associated coastal erosion (Scott and Verkoeyen, 2017).62
SUBMERGENCE AND FLOODING OF ISLANDS AND COASTAL AREAS
In the absence of adaptation, more intense and frequent ESL events, together with trends in coastal
development will increase expected annual flood damages by 2-3 orders of magnitude by 2100 (high
confidence). However, well designed coastal protection is very effective in reducing expected damages and cost
efficient for urban and densely populated regions, but generally unaffordable for rural and poorer areas (high
confidence). Effective protection requires investments on the order of tens to several hundreds of billions of USD
yr-1 globally (high confidence). While investments are generally cost efficient for densely populated and urban areas
(high confidence), rural and poorer areas will be challenged to afford such investments with relative annual costs for
some small island states amounting to several percent of GDP (high confidence). Even with well-designed hard
protection, the risk of possibly disastrous consequences in the event of failure of defences remains.63
In Hawaii and the Caribbean, SLR is projected to exponentially increase flooding, with nearly every centimetre
of SLR causing a doubling of the probability of flooding (Taherkhani et al., 2020).64
Long-term risks of coastal flooding and impacts on populations, infrastructure and assets are projected to increase
with higher levels of warming (high confidence). Tropical regions including small islands are expected to
experience the largest increases in coastal flooding frequency, with the frequency of extreme water-level
events in small islands projected to double by 2050 (Vitousek et al., 2017). Wave-driven coastal flooding risks for
reef-lined islands may increase as a result of coral reef degradation and SLR (Quataert et al., 2015). Exposure to
coastal hazards is particularly high for SIDS, with a significant share of population, infrastructure and assets at risk
(Sections 3.4.5.3 and 3.4.9; Scott et al., 2012; Kumar and Taylor, 2015; Rhiney, 2015; Byers et al., 2018). Limiting
warming to 1.5°C instead of 2°C would spare the inundation of lands currently home to 60,000 individuals in
SIDS by 2150 (Rasmussen et al., 2018). However, such estimates do not consider shoreline response (Section 3.4.5)
or adaptation.65
Reef island and coastal area habitability in small islands is expected to decrease because of increased temperature,
extreme sea levels and degradation of buffering ecosystems, which will increase human exposure to sea-related
hazards (high confidence). Climate and non-climate drivers of reduced habitability are context specific. On small
islands, coastal land loss attributable to higher sea level, increased extreme precipitation and wave impacts and
increased aridity have contributed to food and water insecurities that are likely to become more acute in many
62 SR 1.5C, Section 3.4.9.1
63 SROCC. Technical Summary
64 WGII Chapter 15 Section 15.3.3.1.1
65 SR 1.5C, Box 3.5
30
places (high confidence). In the Caribbean, additional warming by 0.2°–1.0°C, could lead to a predominantly
drier region (5–15% less rain than present day), a greater occurrence of droughts along with associated impacts
on agricultural production and yield in the region. Crop suitability modelling on several commercially important
crops grown in Jamaica found that even an increase of less than + 1.5°C could result in a reduction in the range of
crops that farmers may grow.66
TC intensification in the future is likely to cause severe damage to human settlements and infrastructure in
small islands. Additionally, SLR is expected to cause significant losses and damages (Martyr-Koller et al.,
2021). Based on SLR projections, almost all port and harbour facilities in the Caribbean will suffer inundation
in the future (Cashman and Nagdee, 2017). In Jamaica and St. Lucia, SLR and ESLs are projected to be key risks
to transport infrastructure at 1.5°C unless further adaptation is undertaken (Monioudi et al., 2018).67
HEALTH
Small islands face disproportionate health risks associated with changes in temperature and precipitation,
climate variability, and extremes (Cross-Chapter Box INTERREG in Chapter 16; KR4 in Section 15.3.9, Figure 15.5).
Climate change is projected to increase the current burden of climate-related health risks (Weatherdon et al., 2016;
Ebi et al., 2018; Schnitter et al., 2019). Health risks can arise from exposures to extreme weather and climate events,
including heatwaves; changes in ecological systems associated with changing weather patterns that can result, for
example, in more disease vectors, or in compromised safety and security of water and food; and exposures related
to disruption of health systems, migration, and other factors (see Cross-Chapter Box ILLNESS in Chapter 2; McIver
et al., 2016; Mycoo, 2018a; WHO, 2018).68
Heat-related mortality and risks of occupational heat stress in small island states are projected to increase with
higher temperatures (HoeghGuldberg et al., 2018; Mendez-Lazaro et al., 2018). Higher temperatures can also
affect the productivity of outdoor workers (Taylor et al., 2021). Climate change, urbanisation, and air pollution are
risk factors for the rise of allergic diseases in Asia Pacific (Pawankar et al., 2020).69
Tropical and subtropical islands face risks from vector-borne diseases, such as malaria, dengue fever, and the Zika
virus. El Niño events can increase the risk of diseases such as Zika virus by increasing biting rates, decreasing
mosquito mortality rates and shortening the time required for the virus to replicate within the mosquito (Caminade
et al., 2017). By combining disease prediction models with climate indicators that are routinely monitored,
alongside evaluation tools, it is possible to generate probabilistic dengue outlooks in the Caribbean and early
warning systems (Oritz et al., 2015; Lowe et al., 2018). Projections suggest that more individuals will become
at risk of dengue fever by the 2030s and beyond because of an increasing abundance of mosquitos and larger
geographic range (Ebi et al., 2018). Projected increases in mean temperature could double the dengue burden in
New Caledonia by 2100 (Teurlai et al., 2015). In the Caribbean, Saharan dust transported across the Atlantic can
66 WGII Chapter 15 ES
67 WGII Chapter 15. Section 15.3.4.1
68 WGII Chapter 15. Section 15.3.4.2
69 WGII Chapter 15. Section 15.3.4.2
31
interact with Caribbean seasonal climatic conditions to become respirable and contribute to asthma
presentations at the emergency department (See Table 15.5; Akpinar-Elci et al., 2015).70
LIMITS TO ADAPTATION AND ADAPTIVE CAPACITY
At 1.5°C, limits to adaptation will be reached for several key impacts in SIDS, resulting in residual impacts, as
well as loss and damage (Section 1.1.1, Cross-Chapter Box 12 in Chapter 5). Limiting temperature increase to 1.5°C
versus 2°C is expected to reduce a number of risks, particularly when coupled with adaptation efforts that take into
account sustainable development (Section 3.4.2 and 5.6.3.1, Box 4.3 and 5.3, Mycoo, 2017; Thomas and Benjamin,
2017). Region-specific pathways for SIDS exist to address climate change (Section 5.6.3.1, Boxes 4.6 and 5.3, Cross-
Chapter Box 11 in Chapter 4).71
Risks to natural and human systems are expected to be lower at 1.5°C than at 2°C of global warming (high
confidence). This difference is due to the smaller rates and magnitudes of climate change associated with a 1.5°C
temperature increase, including lower frequencies and intensities of temperature-related extremes. Lower rates of
change enhance the ability of natural and human systems to adapt, with substantial benefits for a wide range of
terrestrial, freshwater, wetland, coastal and ocean ecosystems (including coral reefs) (high confidence), as well as
food production systems, human health, and tourism (medium confidence), together with energy systems and
transportation (low confidence).72
Current ecosystem services from the ocean are expected to be reduced at 1.5°C of global warming, with losses
being even greater at 2°C of global warming (high confidence). The risks of declining ocean productivity, shifts of
species to higher latitudes, damage to ecosystems (e.g., coral reefs, and mangroves, seagrass and other wetland
ecosystems), loss of fisheries productivity (at low latitudes), and changes to ocean chemistry (e.g., acidification,
hypoxia and dead zones) are projected to be substantially lower when global warming is limited to 1.5°C (high
confidence).73
70 WGII Chapter 15 Section 15.3.4.2
71 SR 1.5C, Box 3.5
72 SR1.5C ES
73 SR1.5C ES
32
6. RESEARCH GAPS
Despite intensive study, many knowledge gaps remain due to the complexity of biophysical and social
interactions as well as the local and regional diversity of small islands. Research and data gaps exist in four areas:
island-scale data availability; ecosystem services data; vulnerability and resilience, and adaptation. 74
74 WGII Chapter 15 Section 15.8
33
75
75 WGII Chapter 15 Table 15.8: Research gaps in small islands