INTERNATIONAL COURT OF JUSTICE
OBLIGATIONS OF STATES IN RESPECT OF CLIMATE CHANGE
(REQUEST FOR ADVISORY OPINION)
COMMISSION OF SMALL ISLAND STATES ON CLIMATE CHANGE AND INTERNATIONAL LAW
RESPONSES TO QUESTIONS ASKED BY THE JUDGES
20 DECEMBER 2024
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TABLE OF CONTENTS
I. Question 1 Posed By Judge Cleveland......................................................................... 1
II. Question 2 Posed By Judge Tladi................................................................................. 4
III. Question 3 Posed By Judge Aurescu ........................................................................... 6
IV. Question 4 Posed By Judge Charlesworth .................................................................. 9
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I. Question 1 Posed By Judge Cleveland
During these proceedings, a number of participants have referred to the production of
fossil fuels in the context of climate change, including with respect to subsidies. In your
view, what are the specific obligations under international law of States within whose
jurisdiction fossil fuels are produced to ensure protection of the climate system and
other parts of the environment from anthropogenic emissions of greenhouse gases, if
any?
1. The Commission of Small Island States on Climate Change and International Law
(“COSIS”) submits that consistent with the best available science, States have an obligation to
take all necessary measures to transition away from fossil fuels to ensure protection of the
climate system and other parts of the environment from anthropogenic GHG emissions. This
is the necessary conclusion of taking account of the best available science to inform the
obligations of States under customary and conventional international law.
2. The Court’s jurisprudence has routinely placed science at the heart of its analysis
when assessing environmental risks and determining appropriate measures to mitigate those
risks1. That the minimum core content of States’ environmental obligations is informed by
the science further inheres from the very nature of the prevention obligation in the context of
transboundary environmental harm2, as well as related obligations under other bodies of
international law3. The prevention principle, in particular, takes account of the unique
character of environmental harm and underscores that States must, at a minimum, take
measures necessary not only to cease ongoing, significant harm, but also to avoid material
risk of incremental such harm.
3. In the context of climate change, the best available science informs States’ due
diligence obligations to mitigate and adapt in two principal respects. First, the science
determines the level of risk, including the urgency, and severity of the harm4. Second, the
science establishes the measures that are necessary—that is, indispensable—to mitigate that
risk of harm5. Many participants agree with these fundamental points about the critical role of
the best available science6.
1 Certain Activities Carried Out by Nicaragua in the Border Area (Costa Rica v. Nicaragua), and Construction
of a Road in Costa Rica along the San Juan River (Nicaragua v. Costa Rica), Judgment, I.C.J. Reports 2015,
p. 665 (“Certain Activities”), para. 104; Pulp Mills on the River Uruguay (Argentina v. Uruguay), Judgment,
I.C.J. Reports 2010, p. 14, para. 204; Gabčíkovo-Nagymaros Project (Hungary/Slovakia), Judgment, I.C.J.
Reports 1997, p. 7 (“Gabčíkovo-Nagymaros”), para. 140; Fisheries Jurisdiction Case (Spain v. Canada),
Judgment, I.C.J. Reports 1998, p. 432, paras. 69–70; Alleged Violations of Sovereign Rights and Maritime
Spaces in the Caribbean Sea (Nicaragua v. Colombia), Judgment, I.C.J. Reports 2022, p. 266, para. 58;
Fisheries Jurisdiction Case (United Kingdom v. Iceland), Merits, Judgment, I.C.J. Reports 1974, p. 3, para. 72;
Fisheries Jurisdiction Case (Germany v. Iceland), Merits, Judgment, I.C.J. Reports. 1974, p. 175, para. 64.
2 Gabčíkovo-Nagymaros, para. 140 (“[I]n 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.”).
3 CR 2024/53, pp. 16–19, paras. 6–15 (COSIS).
4 Written Statement of COSIS, paras. 84–86; Written Comments of COSIS, §§ IV.B.1, IV.C; CR 2024/53, p. 17,
para. 8 (COSIS).
5 Written Statement of COSIS, paras. 89–94; Written Comments of COSIS, §§ IV.B.1, IV.C; CR 2024/53,
pp. 14–20, paras. 1–20 (COSIS).
6 Written Comments of COSIS, para. 60 & fn. 139 (citing to all participants’ written statements concurring that
the best available science informs States’ due diligence obligations); see also, e.g., Oral Submissions of: CR
2024/36, p. 17, para. 23 (Antigua and Barbuda); id., p. 61, para. 14 (The Bahamas); id., p. 72, para. 4
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4. The failure of States to mitigate GHG emissions in the face of scientific certainty as to
the causes and impacts of climate change goes back decades and amounts to a breach of due
diligence obligations7. In light of the current, best available science, it is well-settled that
significant harm to human and natural systems is ongoing, and that the risk and severity of
that harm increases with each additional increment of warming. Critically, the risk of
catastrophic harm also rises dramatically with warming beyond 1.5ºC above pre-industrial
levels8. In light of these scientific realities, and when considering this imminent, near-certain
risk of catastrophic—and, in the case of SIDs, existential—harm, ITLOS appropriately
concluded that the standard of due diligence needs to be “stringent”9.
5. In line with this degree of due diligence, States must take the measures indispensable
to cease the ongoing significant harm and avoid further harm to the climate system and other
parts of the environment, including as manifest in the IPCC’s science-driven emissions
pathway in relation to limiting global warming to 1.5ºC above pre-industrial levels10. This
requires States to make deep, rapid, and sustained reductions in GHG emissions according to
the IPCC’s timetable11.
6. With respect to fossil fuel usage in particular, the IPCC has determined that
“[e]stimates of future CO2 emissions from existing fossil fuel infrastructures without
additional abatement already exceed the remaining carbon budget for limiting warming to
1.5°C”12. UNEP similarly concluded that this emissions pathway “mean[s] that most of the
world’s proven fossil fuel reserves must be left unburned”13. On the basis of the best
available science, at COP28, States Parties to the Paris Agreement reached a consensus
Decision on the necessity of “[t]ransitioning away from fossil fuels in energy systems, in a
(Bangladesh); CR 2024/41, p. 22, paras. 12–13 (Siera Leone); CR 2024/51, p. 53, para. 7 (Tuvalu);
CR 2024/53, p. 14, para. 3 & fn. 18 (COSIS) (citing to participants endorsing the IPCC reports as the best
available science).
7 See, e.g., Oral Submissions of: CR 2024/35, p. 110, para. 11 (Vanuatu); CR 2024/36, pp. 85, 88–89 (Barbados).
8 IPCC, “Summary for Policymakers”, Sixth Assessment Synthesis Report (2023), pp. 12, 15; IPCC, “Summary
for Policymakers”, Special Report: Global Warming of 1.5ºC (2018), pp 8–9, 15; IPCC, “Chapter 3: Impacts
of 1.5°C of Global Warming on Natural and Human Systems”, Special Report: Global Warming of 1.5ºC
(2018), p. 254, figure 3.21; Written Comments of COSIS, para. 15 & fn. 13 (citing to all participants’ written
statements concurring on this point); CR 2024/53, p. 15, para. 5(b) & fn. 21 (COSIS) (citing to participants’
written comments and oral submissions concurring on this point); see also id., p. 15, para. 5(a) & fn. 20 (citing
to participants’ written and oral submissions that acknowledge the ongoing and severe harm caused by global
warming).
9 ITLOS, Request for an Advisory Opinion Submitted by the Commission of Small Island States on Climate
Change and International Law (Request for Advisory Opinion Submitted to ITLOS), Case No. 31, Advisory
Opinion, ITLOS Reports 2024 (“COSIS Advisory Opinion”), para. 241.
10 Written Statement of COSIS, § III.B.3; Written Comments of COSIS, § IV.C.; CR 2024/53, pp. 14–20,
paras. 1–21 (COSIS); see also IPCC, “Summary for Policymakers”, Sixth Assessment Synthesis Report (2023),
p. 22 (Table SPM.1).
11 Specifically, the IPCC has assessed that, to have even a 50% chance of staying within the 1.5°C threshold,
States must reduce GHG emissions, as measured against 2019 levels, by at least 43% by 2030, 60% by 2035,
69% by 2040, and 84% by 2050. COSIS Written Comments, para. 80 & fn. 193 (citing to the consensus across
the participants’ written statements); see also, e.g., CR 2024/37, pp. 10–12, paras. 2–3, 10 (Belize); CR
2024/42, p. 31, para. 14 (Marshall Islands); CR 2024/44, p. 23, para. 1 (Liechtenstein); id., p. 36, para. 15
(Malawi); CR 2024/46, p. 48, para. 9 (Palestine); CR 2024/51, p. 55, para. 18 (Tuvalu); CR 2024/54, p. 37,
paras. 48–50 (IUCN).
12 IPCC, “Summary for Policymakers”, Sixth Assessment Synthesis Report (2023), p. 21 (emphasis added).
13 UNEP, Production Gap Report (2019), p. 8; see UNEP, Production Gap Report (2024), p. 2 (“Governments,
in aggregate, still plan to produce more than double the amount of fossil fuels in 2030 than would be consistent
with limiting warming to 1.5°C.”), Emissions Gap Report (2024), pp. XII–XXI (outlining the need for more
drastic GHG reductions).
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just, orderly and equitable manner, accelerating action in this critical decade, so as to achieve
net zero by 2050 in keeping with the science”14.
7. Accordingly, even as States maintain a level of discretion in implementation, in light
of these certain, scientific facts, States have a specific obligation to take all necessary
measures to transition away from fossil fuels, as many States in these proceedings have
recognized15.
8. Vanuatu and the Melanesian Spearhead Group, for example, have urged that “reaching
net-zero emissions by 2050 requires that no new oil, gas or coal projects are approved,
beyond those committed in 2021”16. As Vanuatu observes, the historical reality is that major
emitting States have subsidized, produced, and consumed fossil fuels, notwithstanding their
awareness of the harm posed to the climate system, and today they “continue to implement
policies that expand production of fossil fuels” despite their climate pledges and obligations17.
Several other participants note that States must rapidly transition to clean energy systems,
including by adopting time-bound legislation and regulation phasing fossil fuels out of all
economic sectors18. Five COSIS Member States and a total of 16 parties have likewise joined
the call for a Fossil Fuel Non-Proliferation Treaty19.
9. Participants in these proceedings also emphasize the need to redirect global financial
flows away from the fossil fuel industry, including eliminating subsidies, as part of fulfilling
due diligence obligations 20. This is consistent with the science; the IPCC has concluded that
finance flows are “critical enablers for accelerated climate action” and “[r]emoving fossil fuel
subsidies would reduce emissions”21.
10. Some participants attempt to dilute the content of the obligation to transition away
from fossil fuels or to evade its application by arguing that such an obligation contravenes the
right to economic development and/or sovereignty over natural resources22. However, these
14 COP28, Outcome of the First Global Stocktake, decision -/CMA.5 (Advance Unedited Version)
(13 December 2023), para. 28(d).
15 See, e.g., Written Statements of: African Union, paras. 106–108; OACPS, para. 165; United States, para. 3.39;
Vanuatu, paras. 144–146; see also, e.g., Oral Submissions of: CR 2024/36, pp. 40–41, para. 3(b) (Australia);
CR 2024/39, pp. 35–36, para. 22 (Cote D’Ivoire); CR 2024/40, p. 15, para. 44 (United Arab Emirates); id.,
p. 18, para. 6 (Ecuador); CR 2024/42, p. 19, para. 7 (Cook Islands); id., p. 32, para. 14 (Marshall Islands); CR
2024/44, p. 41, para. 13 (Malawi); CR 2024/47, p. 30, para. 15 (The Netherlands); CR 2024/48, p. 66–67,
para. 7 (Saint Lucia); CR 2024/49, pp. 69–70, para. 13 (The Gambia); CR 2024/50, p. 47, para. 3 (Sri Lanka);
CR 2024/53, pp. 29–30, para. 18 (Pacific Community); CR 2024/54, pp. 11–12, para. 20 (WHO); id., p. 33,
para. 25 (IUCN); see also CR 2024/40, p. 40, para. 4 (United States) (noting the COP28 decision to transition
away from fossil fuels).
16 CR 2024/35, p. 108, para. 7 (Vanuatu and Melanesian Spearhead Group) (citing the IPCC and the
International Energy Agency).
17 Written Comments of Vanuatu, para. 39, see also id., § 2.3.
18 See, e.g., Written Statements of: African Union, paras. 106–108; The Bahamas, para. 184; IUCN, paras. 77–
78; Seychelles, para. 132–133; Written Comments of The Gambia, paras. 4.5, 5.6, 5.13; CR 2024/35, p. 108,
para. 7 (Vanuatu and Melanesian Spearhead Group).
19 The Fossil Fuel Non-Proliferation Treaty Initiative, “Who has Joined the call for a Fossil Fuel Non-
Proliferation Treaty?”, available at https://fossilfueltreaty.org/endorsements/#governments.
20 See, e.g., Oral Submissions of: CR 2024/48, pp. 66–67, para. 7 (Saint Lucia); CR 2024/54, pp. 11–12, para. 20
(WHO). See also Paris Agreement, United Nations Treaty Series, Vol. 3156, p. 79 (2015) (“Paris
Agreement”), Art. 2(1)(c).
21 IPCC, “Longer Report”, Sixth Assessment Synthesis Report (2023), p. 79.
22 See, e.g., Oral Submissions of: CR 2024/40, pp. 11–14, paras. 21–35 (United Arab Emirates); CR 2024/42,
p. 50, paras. 29–30 (India); CR 2024/43, p. 57, para. 17 (Kuwait); CR 2024/51, p. 26, para. 17 (Timor Leste).
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rights are subject to limitation in the context of environmental protection23. As the Court has
recognized, “[t]hroughout the ages, mankind has, for economic or other reasons, constantly
interfered with nature . . . . often . . . without consideration of the effects upon the
environment”24. However, “[o]wing to new scientific insights and to a growing awareness of
the risks for mankind”, there is a “need to reconcile economic development with protection of
the environment”25. Thus, neither the right to development nor sovereign rights over one’s
natural resources offers a State “carte blanche” to degrade the global environment.
11. Relatedly, the principle of CBDR-RC does not allow States to justify the continued
production, export, or consumption of fossil fuels, contrary to what has been suggested by a
minority of participants26. As ITLOS held, and as many participants in these proceedings
agree27, “[a]ll States must make mitigation efforts”28. Indeed, the science is clear that going
forward, the remaining carbon budget to stay within 1.5°C will not allow States to opt out of
their obligations to make deep, rapid, and sustained GHG emission reductions, including the
necessity of transitioning away from fossil fuels29. Further, the CBDR-RC argument is based
on a false premise. Climate action and economic development are not mutually exclusive.
The science is instructive in this regard as the IPCC has concluded that the necessary
emissions reductions can be “achieved synergistically” with economic development30.
12. In sum, all States have a specific obligation to take all necessary measures to cease
ongoing significant harm and avoid further harm to the climate system and other parts of the
environment, and with respect to fossil fuel-producing States in particular, this requires
transitioning away from fossil fuels, in accordance with the best available science.
II. Question 2 Posed By Judge Tladi
In their written and oral pleadings, participants have generally engaged in an
interpretation of the various paragraphs of Article 4 of the Paris Agreement. Many
participants have, on the basis of this interpretation, come to the conclusion that, to the
extent that Article 4 imposes any obligations in respect of Nationally Determined
Contributions, these are procedural obligations. Participants coming to this conclusion
have, in general, relied on the ordinary meaning of the words, context and sometimes
some elements in Article 31(3) of the Vienna Convention on the Law of Treaties. I would
like to know from the participants whether, according to them, “the object and
purpose” of the Paris Agreement, and the object and purpose of the climate change
23 See, e.g., Report of the United Nations Conference on the Human Environment, document
A/CONF.48/14/Rev.1 (16 June 1972), § 1 (Declaration of the United Nations Conference on the Human
Environment) (“Stockholm Declaration”), Principle 21; Rio Declaration on Environment and Development,
document A/CONF.151/26 (Vol. I) (Annex I) (12 August 1992) (“Rio Declaration”), Principle 2; COSIS
Advisory Opinion, paras. 184–187.
24 Gabčíkovo-Nagymaros, para. 140.
25 Id. (emphasis added).
26 See, e.g., CR 2024/36, pp. 26–27, para. 3 (Saudi Arabia); id., p. 32, para. 7; Written Statement of India,
paras. 37, 39(vii).
27 Written Comments of COSIS, para. 69 & fn. 160.
28 COSIS Advisory Opinion, para. 229 (emphasis added).
29 Written Statement of COSIS, §§ II.B.4–5.
30 IPCC, “Chapter 2: Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development”,
Special Report on 1.5°C (2018), p. 97; see also see also IPCC, “Chapter 17: Accelerating the Transition in
the Context of Sustainable Development”, Sixth Assessment Report: Mitigation of Climate Change (2022),
pp. 1739–1742; see also CR 2024/54, p. 12, para. 23 (WHO) (pointing to numerous co-benefits of taking
action to address climate change and concluding that “every US dollar spent on specific climate and health
actions will bring an average return of US$4”).
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treaty framework in general, has any effect on this interpretation and if so, what effect
does it have?
13. As COSIS has previously observed, Article 4 of the Paris Agreement contains largely
procedural obligations31. Contrary to the view taken by some States32, the Paris Agreement’s
procedural obligations contained in Article 4 are not merely discretionary. Article 4, by its
terms, obligates States Parties to “prepare, communicate and maintain” NDCs that “reflect
[the State’s] highest possible ambition” towards the overarching objective “to achieve the
long-term temperature goal” of 1.5°C above pre-industrial levels33.
14. Consistent with Article 31(1) of the Vienna Convention on the Law of Treaties
(“VCLT”), the interpretation of the plain text of Article 4 requires consideration of the object
and purpose of the Paris Agreement, such that, as submitted by Antigua and Barbuda, “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”34. Likewise, several participants also point out that considering Article 4
in light of the object and purpose of the Paris Agreement again yields the conclusion that
States are constrained in their selection of NDCs35. Under the plain text of Article 4(3),
successive NDCs must represent a “progression” as well as reflect that State’s “highest
possible ambition”36. Further, looking to the preamble, the Paris Agreement aims at
“effective and progressive” action against the “urgent threat of climate change on the basis of
the best available scientific knowledge”37. As such, properly interpreted, Article 4 requires
that States align their NDCs with the overall temperature goal of the Paris Agreement and the
IPCC’s emissions pathway, as well as ensure successively progressive commitments38.
15. Participants also point out that States must exercise best efforts to achieve their
NDCs39, again due to the object and purpose of the Paris Agreement, but also on account of
harmonization of the Paris Agreement with other relevant rules of international law40. As
COSIS recognized in its Written Comments, nothing in the UNFCCC and/or the Paris
Agreement suggests that either was intended to cover the field in terms of the international
response to climate change exclusively and exhaustively41. As such, neither the UNFCCC
31 Written Comments of COSIS, paras. 71–72; see generally id., § IV.B.3.; CR 2024/53, p. 21, para. 4 (COSIS).
32 See, e.g., Written Statements of: Saudi Arabia, paras. 4.64-4.68; United States, paras. 3.17–3.18; Written
Comments of United Kingdom, paras. 14–18, 21–22.
33 Paris Agreement, Arts. 2(1)(a), 4.
34 Written Statement of Antigua and Barbuda, para. 241.
35 See, e.g., Written Statements of: Ecuador, paras. 3.76–3.77, 3.81; European Union, paras. 126–132; Latvia,
para. 29; New Zealand, paras. 48–52, 54, 59, 61; Vanuatu, paras. 408–413, 418–421.
36 Paris Agreement, Art. 4(3).
37 Id., Preamble.
38 See id., Arts. 2, 4, Preamble; see also Vienna Convention on the Law of Treaties, United Nations Treaty Series,
Vol. 1155, p. 331 (1969) (“VCLT”), Art. 31; see also, e.g., Written Statements of: Antigua and Barbuda, para.
295; IUCN, paras. 125–151.
39 See, e.g., Written Statements of: Antigua and Barbuda, para. 295; Ecuador, paras. 3.76–3.77; Latvia,
paras. 29–30; South Korea, para. 20; Oral Submissions of: CR 2024/35, pp. 142–144, paras. 10–23 (Germany);
CR 2024/39, p. 30, para. 14 (Côte d’Ivoire); CR 2024/41, p. 59, paras. 25–27 (Guatemala); CR 2024/43, p. 36,
paras. 22–25 (Kenya); id., pp. 49–50, paras. 34–35 (Kiribati); CR 2024/44, p. 13, paras. 8–9 (Latvia); see also
Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America),
Judgment, I.C.J. Reports 1986, p. 14, para. 276 (finding a violation of the obligation not to defeat the object
and purpose of the treaty).
40 CR 2024/53, pp. 21–25, paras. 1–21 (COSIS).
41 Written Comments of COSIS, § IV.B.3, para. 72.
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nor the Paris Agreement constitutes a “self-contained regime” that applies to the exclusion of
general international law42.
16. Likewise, neither instrument was intended to displace other sources of international
law43, nor, as ITLOS has found, does either instrument in fact displace other obligations44.
There is no actual inconsistency between obligations under these instruments and general
sources of international law, including the obligations to prevent transboundary harm, Part
XII of UNCLOS, and human rights obligations45. This means that the Paris Agreement is
informed by States’ obligations to reduce GHG emissions under these other rules of
international law. Article 4 thus requires States to pursue NDCs in good faith, through
progressively ambitious commitments, as necessary contributions to the reduction of GHG
emissions. At the same time, Article 4 does not affect States’ rights and obligations under
customary international law, UNCLOS, and other instruments, which compel significant
reductions in GHG emissions in parallel.
III. Question 3 Posed By Judge Aurescu
Some participants have argued, during the written and / or oral stages of the
proceedings, that there exists the right to a clean, healthy and sustainable environment
in international law. Could you please develop what is, in your view, the legal content of
this right and its relation with the other human rights which you consider relevant for
this advisory opinion?
17. The right to a clean, healthy, and sustainable environment draws roots in a variety of
sources, ranging from the Stockholm Convention46 and the Rio Declaration47 to the
International Covenant on Economic, Social, and Cultural Rights48 and numerous other major
42 Id.; see also CR 2024/53, pp. 21–25, paras. 1–21 (COSIS).
43 Written Comments of COSIS, § IV.B.3, para. 74.
44 COSIS Advisory Opinion, para. 224.
45 Written Comments of COSIS, § IV.B.3, para. 70.
46 Stockholm Declaration, Principle 1 (“[Humanity] has the fundamental right to freedom, equality and adequate
conditions of life, in an environment of a quality that permits a life of dignity and well-being, and…bears a
solemn responsibility to protect and improve the environment for present and future generations.” (emphasis
added)).
47 Rio Declaration, Principle 10.
48 International Covenant on Economic, Social, and Cultural Rights, United Nations Treaty Series, Vol. 993,
p. 3 (1966) (Dossier No. 52), Art. 12(2)(b).
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human rights treaties49, as multiple participants in these proceedings have noted50. The Inter-
American Court of Human Rights (“IACtHR”)51 and the African Commission on Human and
Peoples’ Rights52 have notably also upheld the right to a healthy environment, as has the
European Court of Human Rights53.
18. In these proceedings, at least 53 States and international organizations recognize in
their written and oral statements the human right to a clean, healthy, and sustainable
environment and that climate change is undermining this right54. Likewise, some four-fifths
of States have recognized this right in their domestic law, at the national or the regional
level55.
49 Additional Protocol to the American Convention on Human Rights in the Area of Economic, Social and
Cultural Rights (“Protocol of San Salvador”), OAS Treaty Series, No. 69 (1988), Art. 11 (“Everyone shall
have the right to live in a healthy environment and to have access to basic public services.”); African Charter
on Human and Peoples’ Rights, United Nations Treaty Series, Vol. 1520, p. 217 (1981), Art. 24 (“All peoples
shall have the right to a general satisfactory environment favourable to their development”); Maputo Protocol
to the African Charter on Human and Peoples’ Rights on the Rights of Women in Africa, United Nations
Treaty Series, Vol. 3268 (2003), Art. 18(1) (“Women shall have the right to live in a healthy and sustainable
environment.”); Council of the League of Arab States, Arab Charter on Human Rights, reprinted in 12 Int’l
Hum. Rts. Rep. 893 (2005), Art. 38 (“Every person has the right to an adequate standard of living for himself
and his family, which ensures their well-being and a decent life, including … the right to a healthy
environment.”); see also Association of Southeast Asian Nations (“ASEAN”), ASEAN Human Rights
Declaration (2012), Art. 28(f) (“Every person has the right to an adequate standard of living for himself or
herself and his or her family including … [t]he right to a safe, clean and sustainable environment.”);
Organization of American States, American Declaration on the Rights of Indigenous Peoples, AG/RES.2888
(XLVI-O/16) (2016), Art. 19(1) (“Indigenous peoples have the right to live in harmony with nature and to a
healthy, safe, and sustainable environment, essential conditions for the full enjoyment of the right to life, to
their spirituality, worldview and to collective well-being.”).
50 See, e.g., Written Statement of Vanuatu, paras. 378–380, fn. 753; Written Comments of: Albania, para. 36;
Chile, para. 28; Samoa, para. 133; Oral Submissions of: CR 2024/41, p. 36, para. 22 (Ghana); CR 2024/44,
p. 30, para. 24 (Liechtenstein); CR 2024/50, p. 23, para. 5 (Slovenia).
51 Inter-American Court of 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, Case No. OC-23/17, Advisory
Opinion (15 November 2017).
52 African Commission on Human and Peoples’ Rights, Case of the Social and Economic Rights Center (SERAC)
and Center for Economic and Social Rights (CESR) v. Nigeria, Communication 155/96, Decision of
October 27, 2001, paras. 51–53.
53 See, e.g., European Court of Human Rights, Case of Di Sarno v. Italy, Application no. 30765/08, Judgment
(10 January 2012), para. 110.
54 See Written Statements of: African Union, paras. 62, 192; Albania, para. 96; Antigua and Barbuda, paras. 180–
185; Argentina, para. 38; The Bahamas, para. 141; Bangladesh, para. 110; Barbados, paras. 164–166; Bolivia,
para. 17; Burkina Faso, paras. 215–219; Canada, para. 24; Chile, para. 64; Colombia, para. 3.67; Cook Islands,
para. 214; COSIS, para. 132; Costa Rica, paras. 81–82; Democratic Republic of the Congo, paras. 147–156;
Ecuador, paras. 3.103–3.108; El Salvador, paras. 42–43; European Union, § 4.6.2.2; Grenada, para. 65; IUCN,
para. 481; Kenya, paras. 5.73–5.75; Republic of Korea, para. 28; Liechtenstein, paras. 45–47; Madagascar,
§ III.D.2; Marshall Islands, para. 113; Mauritius, paras. 184–185; Melanesian Spearhead Group, paras. 283–
289; Mexico, paras. 87–96; Federated States of Micronesia, paras. 78–80; Namibia, paras. 121–126; Nepal,
para. 31; Netherlands, paras. 3.27, 3.34; Philippines, paras. 11, 54; Portugal, para. 69; Saint Vincent and the
Grenadines, paras. 37, 120–123; Seychelles, paras. 136–145; Sierra Leone, § 2.II.F; Slovenia, § II.A;
Solomon Islands, para. 1.7; Spain, paras. 14–17; Sri Lanka, para. 94(b); Thailand, para. 27; Timor-Leste,
para. 298; Tuvalu, para. 100; Vanuatu, § 4.4.4.C; Written Comments of: Cameroon, para. 86; The Gambia,
paras. 3.37–3.38; Kiribati, paras. 42–45; OACPS, para. 51; Samoa, paras. 130–140; Uruguay, paras. 107–115;
CR 2024/41, pp. 36–37 (Ghana).
55 See CR 2024/50, p. 23 (Slovenia); see also UN General Assembly, 77th Session, Note by the UN Secretary-
General, Human Rights Obligations Relating to the Enjoyment of a Safe, Clean, Healthy and Sustainable
Environment, 10 August 2022, para. 26 (“[M]ore than 80 per cent of Member States (156 of 193) legally
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19. This widespread recognition of the right to a clean, healthy, and sustainable
environment in these proceedings is consistent with the voting record for UN General
Assembly Resolution 76/30056 as well as UN Human Rights Council’s Resolution 48/1357,
both of which attracted vast support58 and saw no States voting in opposition.
20. Only a handful of States in these proceedings question the customary status of this
right to a clean, healthy, and sustainable environment59. These States argue that in order for
the right to develop as a customary norm of international law, the treaty-making process must
be followed60. In doing so, however, these States attempt to impose a treaty requirement on
the very definition of custom61, which, of course, the Court does not require.
21. States recognizing the right to a clean, healthy, and sustainable environment recall that
protection of the right is necessary for the enjoyment and fulfilment of other human rights,
including the rights to life and to an adequate standard of living62. Many States consider the
right to be fundamental for this reason, with a few States referring to the right as peremptory
in nature63.
22. As to the content of the right, it contains both substantive and procedural obligations.
On the substantive side, it requires the establishment, maintenance, and enforcement of
effective legal and institutional frameworks that regulate, inter alia, air quality, the global
climate, freshwater quality, food quality, marine pollution, waste, toxic substances, protected
recognize the right to a clean, healthy and sustainable environment, establishing binding duties for
Governments.”).
56 General Assembly, resolution 76/300, The Human Right to a Clean, Healthy and Sustainable Environment,
document A/76/300 (1 August 2022).
57 United Nations Human Rights Council, resolution 48/13, The Human Right to a Clean, Healthy and
Sustainable Environment, document A/HRC/RES/48/13 (8 October 2021).
58 See United Nations, Press Release, “With 161 Votes in Favour, 8 Abstentions, General Assembly Adopts
Landmark Resolution Recognizing Clean, Healthy, Sustainable Environment as Human Right” (28 July 2022),
available at https://press.un.org/en/2022/ga12437.doc.htm (Belarus, Cambodia, China, Ethiopia, Iran,
Kyrgyzstan, the Russian Federation, and Syria abstained). See also COP16, Kunming-Montreal Global
Biodiversity Framework, decision 15/4 (19 December 2022), para. 7(g).
59 See Written Statements of: Germany, paras. 104–106; Indonesia, paras. 42–43; Latvia, para. 64; Tonga, para.
244; United States, paras. 4.54–4.58; Written Comments of: Australia, para. 4.18; New Zealand, p. 11; Saudi
Arabia, para. 4.46; United Kingdom, para. 53; Oral Submissions of: CR 2024/38, p. 17, para. 33 (Canada);
CR 2024/50, p. 69, para. 43 (Serbia).
60 See Written Statements of: Indonesia, para. 42–43; United States, paras. 4.54–4.58; Written Comments of
New Zealand, p. 11; Oral Submissions of: CR 2024/38, p. 17 (Canada); CR 2024/40, p. 47 (United States).
61 See also North Sea Continental Shelf (Federal Republic of Germany/Netherlands), Judgment, I.C.J. Reports
1969, p. 4.
62 See, e.g., Written Statements of: Portugal, paras. 70–78; Vanuatu, para. 381; Written Comments of Sri Lanka,
para. 39; CR 2024/41, p. 37, para. 24 (Ghana); see also Human Rights Committee, General Comment No. 36,
Right to Life, para. 65; Inter-American Court of 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,
Case No. OC-23/17, Advisory Opinion (15 November 2017), p. 59 (“[A] healthy environment is a
fundamental right for the existence of humankind.”); COP28, Outcome of the First Global Stocktake, decision
-/CMA.5 (Advance Unedited Version) (13 December 2023), p. 2 (“[C]limate change is a common concern of
humankind and that Parties should, when taking action to address climate change, respect, promote and
consider their respective obligations on human rights, the right to a clean, healthy and sustainable
environment.”).
63 See Written Statements of: Costa Rica, para. 82; Ecuador, para. 3.108; El Salvador, para. 42; European Union,
para. 258; Melanesian Spearhead Group, paras. 284–286; Philippines, para. 54; Sierra Leone, para. 3.117; Sri
Lanka, para. 94(b); Vanuatu, para. 379; Written Comments of Kiribati, p. 15.
9
areas, conservation and biological diversity64. Participants in these proceedings further recall
that the right to a healthy environment entails procedural obligations, including to ensure
access to environmental information, public participation in environmental decision-making,
and access to environmental justice65.
23. In terms of the scope of the right, COSIS submits that the right applies to present and
future generations66, owing to both its individual and collective dimensions, as recognized by
the IACtHR67. In terms of its geographic dimension, the right applies to the prevention and
curtailment of environmental harm that threatens individuals within the State’s jurisdiction68.
But the right also applies extraterritorially to protect natural systems even beyond political
borders, as it encompasses the customary due diligence obligation of preventing
transboundary harm69. In this regard, UN General Assembly Resolution 76/300 recognizing
the right refers to the prevention of losses of biodiversity, protection of air, land, and water
resources from pollution, as well as the need for protection in the face of climate change70.
IV. Question 4 Posed By Judge Charlesworth
In your understanding, what is the significance of the declarations made by some States
on becoming parties to the UNFCCC and the Paris Agreement to the effect that no
provision in these agreements may be interpreted as derogating from principles of
general international law or any claims or rights concerning compensation or liability
due to the adverse effects of climate change?
24. COSIS observes that several States, including several COSIS Member States, made
declarations upon joining the UNFCCC and the Paris Agreement to the effect that:71
(a) “no provisions in the Convention can be interpreted as derogating from the
principles of general international law”;
(b) “the Paris Agreement and its application shall in no way constitute a
renunciation of any rights under international law concerning State
responsibility for the adverse effects of climate change and that no provision in
the Paris Agreement can be interpreted as derogating from principles of
64 See, e.g., Written Comments of: Chile, pp. 12–13; Vanuatu, p. 91; CR 2024/40, p. 33, para. 10 (Spain);
CR 2024/44, p. 30 (Liechtenstein).
65 See, e.g., Written Comments of Vanuatu, p. 91, fn. 314; CR 2024/40, p. 33, para. 10 (Spain).
66 See, e.g., Written Comments of Vanuatu, p. 91.
67 Inter-American Court of 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, Case No. OC-23/17, Advisory
Opinion (15 November 2017), para. 59.
68 CR 2024/50 pp. 24–25, para. 9 (Slovenia).
69 See, e.g., Written Statements of: Portugal, para. 86; Vanuatu, para. 382; Written Comments of: Chile,
paras. 38–42; Vanuatu, p. 91.
70 General Assembly, resolution 76/300, The Human Right to a Clean, Healthy and Sustainable Environment,
document A/76/300 (1 August 2022), p. 2.
71 In relation to the UNFCCC, such declarations were made by: Fiji, Kiribati, Nauru, Papua New Guinea, and
Tuvalu. In relation to the Paris Agreement, such declarations were made by: Cook Islands, Federated States
of Micronesia, Nauru, Niue, Solomon Islands, Tuvalu, and Vanuatu. See Status of United Nations Framework
Convention on Climate Change, United Nations Treaty Collection, available at
https://treaties.un.org/pages/ViewDetailsIII.aspx?src=TREATY&mtdsg_no=XXVII-
7&chapter=27&Temp=mtdsg3&clang=_en; Status of Paris Agreement, United Nations Treaty Collection,
available at https://treaties.un.org/pages/viewdetails.aspx?src=treaty&mtdsg_no=xxvii-7-
d&chapter=27&clang=_en.
10
general international law or any claims or rights concerning compensation
due to the impacts of climate change”; or
(c) “no provision in the Paris Agreement can be interpreted as derogating from
principles of general international law or any claims or rights concerning
compensation due to the impacts of climate change”.
25. These declarations—largely made by States that recognize their unique and existential
vulnerability to the worst effects of climate change—emphasize that neither the UNFCCC nor
the Paris Agreement should be understood as displacing rights and obligations in respect of
climate change under general international law sources. While these interpretive declarations
are not binding, they may be taken into account, per Article 31(2) of the VCLT, as part of the
“context” for interpreting provisions under the UNFCCC and the Paris Agreement72.
26. These declarations—none of which encountered objection—confirm that neither the
UNFCCC nor the Paris Agreement was intended to displace other international law
obligations or restrict any responsibilities incurred by States under such obligations73. There
is no “actual inconsistency” of obligations between these sources74. As ITLOS held in its
COSIS Advisory Opinion, “[w]hile the Paris Agreement complements [UNCLOS] in relation
to the obligation to regulate marine pollution from anthropogenic GHG emissions, the former
does not supersede the latter”75. The Paris Agreement and UNCLOS are “separate
agreements, with separate sets of obligations”76. The same is true of other obligations,
including the customary obligation on transboundary harm and human rights obligations77.
27. Moreover, there is no indication of any intention in either climate treaty to displace
other sources of international law. To the contrary, both the UNFCCC and the Paris
Agreement contain language suggesting that obligations were meant to complement and
reinforce customary rules of international law related to the protection of the environment78.
And as The Bahamas notes, the UNFCCC also recalls the Stockholm Declaration, which in
turn references protection of the environment for purposes of the enjoyment of human
rights79. The Paris Agreement likewise expressly calls upon States to “respect, promote and
consider their respective obligations on human rights”80. Moreover, nothing in the
72 See VCLT, Art. 31(2); O. Dörr et al. (eds.), “Article 19: Formulation of Reservations”, in Vienna Convention
on the Law of Treaties: A Commentary (2018), p. 264; Guide to Practice on Reservations to Treaties, Yearbook
of International Law Commission, Vol. II, Part Two, document A/66/10 (2011), Guideline 3.1.
73 Written Comments of COSIS, § IV.B.3; see also COSIS Advisory Opinion, paras. 223–224.
74 Articles on Responsibility of States for Internationally Wrongful Acts, with Commentaries, Yearbook of the
International Law Commission, 2001, Vol. II (Part Two), p. 140, Commentary to Art. 55, para. 4 (referring to
an “actual inconsistency between [sources], or else a discernible intention that one provision is to exclude the
other”); Conclusions of the work of the Study Group on the Fragmentation of International Law: Difficulties
arising from the Diversification and Expansion of International Law, Yearbook of the International Law
Commission, Vol. II, Part Two, document A/61/10 (2006), pp. 408, 414.
75 COSIS Advisory Opinion, para. 223.
76 Id.
77 See, e.g., Certain Activities, para. 108.
78 United Nations Framework Convention on Climate Change, United Nations Treaty Series, Vol. 1771, p. 107
(1992), Preamble (“States have, in accordance with the Charter of the United Nations and the principles of
international law, . . . 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 . . . .”); Paris
Agreement, Art. 2(1) (“This Agreement, in enhancing the implementation of the Convention, including its
objective, aims to strengthen the global response to the threat of climate change, in the context of sustainable
development and efforts to eradicate poverty, including by . . . ” (emphasis added)).
79 Written Comments of The Bahamas, para. 20.
80 Paris Agreement, Preamble.
11
negotiating history of either instrument suggests an intention to displace general international
law sources81.
28. COSIS thus agrees with numerous States that the declarations provide further support
for the conclusion that neither climate treaty constitutes lex specialis and that other sources of
climate-related obligations continue to apply in parallel82. Notably, the few, largely highemitting
States that disagree on the relationship between the UNFCCC and the Paris
Agreement and general international law do not actually take a different position on these
declarations83.
29. These declarations made also underscore that the loss and damage mechanisms
provided for under the Paris Agreement coexist with, and do not displace, general
international law regimes of State responsibility, as COSIS noted in its Written Comments84.
In this respect, the declarations just reaffirm that any loss and damage included in the Paris
Agreement is complementary to options for redress available under general customary rules
of State responsibility. In doing so, as already noted, they met with no objection, meaning
that the ILC’s strong presumption against finding displacement absent a clear “intent” to
displace is not overcome in this context85. COSIS accordingly agrees with numerous other
participants86 that States continue to incur responsibility under general international law for
harms resulting from the breaches of obligations considered in Part (a).
81 Written Comments of The Bahamas, para. 20; see also Elettronica Sicula S.p.A. (ELSI) (United States of
America v. Italy), Judgment, I.C.J. Reports 1989, p. 15, para. 50 (explaining that the Court should not “accept
that an important principle of customary international law should be held to have been tacitly dispensed with,
in the absence of any words making clear an intention to do so”); see generally Southern Bluefin Tuna (New
Zealand v. Japan; Australia v. Japan), Jurisdiction and Admissibility, Award of 4 August 2000, XXIII RIAA
1, pp. 40–41, para. 52 (“There is no reason why a given act of a State may not violate its obligations under
more than one treaty”).
82 Oral Submissions of: CR 2024/36, p. 82, para. 5 (Barbados); CR 2024/37, pp. 10–11, para. 5 (Belize); CR
2024/43, p. 49, para. 33 (Kiribati); CR 2024/46, p. 8, para. 2 (Nauru); Written Statements of: Albania,
para. 129 & fn. 195; Mauritius, para. 123; Samoa, paras. 134–135 & fns. 56, 58; Sierra Leone, para. 3.134 &
fn. 408; Vanuatu, para. 433; Written Comments of: Antigua & Barbuda, paras. 94–95; Bahamas, para. 20;
Barbados, para. 34; Belize, para. 37; Cook Islands, para. 56(c); DRC, para. 44; Egypt, para. 72; Gambia,
para. 5.4; MSG, para. 188; Namibia, para. 59; Nauru, paras. 30–31; OACPS, para. 82; Pakistan, para. 20; Sri
Lanka, para. 63.
83 See, e.g., Oral Submissions of: CR 2024/36, pp. 28–30, paras. 5–11 (Saudi Arabia); CR 2024/38, pp. 29–30,
paras. 8–9 (China); CR 2024/42, pp. 46–47, para. 11 (India); CR 2024/43, pp. 54–59, paras. 2–23 (Kuwait).
84 Written Comments of COSIS, para. 93; see also C. Voigt, “International Responsibility and Liability”, Oxford
Handbook of International Environmental Law (J. Rajamani & J. Peel eds., 2d ed. 2021), pp. 1008–1010.
85 Conclusions of the work of the Study Group on the Fragmentation of International Law: Difficulties arising
from the Diversification and Expansion of International Law, Yearbook of the International Law Commission,
Vol. II, Part Two, document A/61/10 (2006), pp. 413–414.
86 Written Comments of COSIS, paras. 106–108 & fns. 247 & 250 (citing to participants’ written statements
agreeing that the law of State responsibility applies alongside the UNFCCC and Paris Agreement).
Written reply of the Commission of Small Island States to the questions put by Judges Cleveland, Tladi, Aurescu and Charlesworth at the end of the hearing held on 13 December 2024