21 Oct Blog: The ICJ Advisory Opinion on climate change and the interrelationship between environmental protection and human rights

In this month’s blog we reflect on the landmark Advisory Opinion of the International Court of Justice (“ICJ”) on states’ obligations regarding to climate change, including the link between environmental protection and human rights, the importance of which is increasingly being recognised by both the international and domestic courts.

Background

The request for an advisory opinion from the ICJ began with a historic grassroots movement by young people in pacific-island states, concerned about the long-term impacts of climate change on their communities.

On 29 March 2023, the United Nations General Assembly, through Resolution 77/276, requested the ICJ to deliver an advisory opinion on:

• 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 present and future generations; and
• the legal consequences arising from these obligations for the states that 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; and (ii) peoples and individuals of the present and future generations affected by the adverse effects of climate change.

The ICJ proceedings had the highest level of state participation in the Court’s history, with more than 90 written submissions and over 100 oral statements.

On 23 July 2025, the ICJ rendered its advisory opinion, unanimously affirming the binding and enforceable nature of state obligations in respect of climate change.

Key findings

The ICJ in its Advisory Opinion adopted the Intergovernmental Panel on Climate Change definition of climate change: “change in the state of the climate that… may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use”.[1] Importantly, the ICJ relied on information from authoritative scientific sources as a basis for its approach and understanding of climate change and linked issues – rather than adopting its own formulations. This enabled the ICJ to treat the Paris Agreement as not merely aspirational, but as creating legally binding and enforceable duties, with the goal of keeping global warming below 1.5°C above pre-industrial levels determined by the ICJ to be the agreed upon standard for climate policies (§224).

Importantly, the ICJ affirmed that “States have a duty under customary international law to prevent significant harm to the environment” (§132), and found that all states are under a duty to achieve “deep, rapid, and sustained reductions” in emissions to prevent significant harm to the climate system (§282).

The precedence of climate change law: Lex Specialis?

The participants in the ICJ proceedings expressed divergent views on the precedence of climate change treaties (such as the United Nations Framework Convention on Climate Change and the Paris Agreement) over other norms of international law including human rights obligations, in the context of climate change. Some participants argued that the climate change treaties constitute lex specialis, in that they supersede other international law norms. Others argued that the climate treaties form part of a broader set of rules applicable to climate change context.

The ICJ concluded that the object and purpose of climate change treaties do not conflict with other international law norms and rejected lex specialis arguments that these treaties generally exclude the application of other international norms (§§169-172). Accordingly, the ICJ held that climate treaties coexist with other international norms including human rights (§§145, 172). This finding is consistent with decisions of other human rights courts and bodies, which have affirmed the application of the human rights obligations in the climate change context, even where they are also governed by climate change treaties.[2]

Relevance of human rights law in the context of climate change

In its Advisory Opinion, the ICJ affirmed that a clean, healthy and sustainable environment is a “precondition” for the enjoyment of multiple human rights (§393) and observed that the adverse effects of climate change hinder effective enjoyment of various human rights such as the rights to life, health, and an adequate standard of living (§§376-381).

In particular, the ICJ recognised that displacement caused by climate change may trigger the principle of non-refoulement under the right to life (Article 6) in the International Covenant on Civil and Political Rights, in cases where returning individuals from the countries to which they have been displaced would expose them to “a real risk of irreparable harm to the right to life”.[3] The ICJ also further referenced the impact of climate change on the rights of particular groups of persons, including women, children, indigenous people, migrants, and persons with disabilities (§§382-384).

The ICJ went on to determine unanimously that states bear obligations under international human rights law “to respect and ensure the effective enjoyment of human rights by taking necessary measures to protect the climate system and other parts of the environment” (§§404, 457).

The ICJ’s Advisory Opinion follows the Verein KlimaSeniorinnen judgment, in which the European Court of Human Rights (“ECtHR”) found that climate change “poses a serious current and future threat” to the enjoyment of rights  as enshrined in the European Convention on Human Rights (“ECHR”).[4] The ECtHR stated that the right to respect for private and family life (Article 8, ECHR) encompasses a right to “effective protection by the State authorities from serious adverse effects of climate change on their life, health, well-being and quality of life” (§519).

The United Nations General Assembly, in Resolution 76/300 of 28 July 2022, recognised an autonomous human right to a clean, healthy and sustainable environment. The ECtHR regarded this in the Verein litigation as a non-binding legal source as one of the several international initiatives towards recognition of a human rights to a clean, healthy and sustainable environment (§448). However, the ECtHR considered that it was beyond its competence to determine whether these initiatives give rise to a specific legal obligation under the ECHR.

The Inter-American Court of Human Rights (“IACtHR”) has gone even further in an advisory opinion earlier this year, emphasising that the protection of the climate system acquires “specific and differentiated” characteristics, reflecting the urgency, specificity and complexity of the measures required. On that basis, the IACtHR recognised the autonomous right to a healthy climate under the American Convention on Human Rights (“ACHR”).[5] The IACtHR also recognised “nature” as a “subject” of rights under the ACHR as it is a “contemporary expression” of the interdependence between human rights and the environment (§282).

Domestic Courts

In terms of the domestic Courts, in the landmark 2024 case of R (Finch) v Surrey County Council and Others, [2024] UKSC 20 the UK Supreme Court determined that the impact of burning fossil fuels should be considered when granting permission for drilling sites.

Last year Mr Justice Fordham also held in the case of R (Fighting Dirty Ltd) v (1) The Environment Agency and (2) The Secretary of State for Environment Food and Rural Affairs [2024] EWHC 2029 (Admin), that, in certain environmental challenges, a higher standard of scrutiny is appropriate when determining whether a public body’s decision is “reasonable” in the Wednesbury sense. Importantly, Mr Justice Fordham held: “I would not accept, in the context of environment protection, a fixed focus on “human” rights; as distinct from fundamental rights, interests and values. Where “an important individual interest is at stake” is only an “instance” of “more intense scrutiny where the circumstances require it” (De Smith §6 108). Nor can I accept a characterisation of environmental protection as “a matter” which does not “raise… issues of real importance to individuals” (De Smith §6 063). On an international plane, the lexicon embraces “the right to a clean, healthy and sustainable environment” as a “human right” (Verein §144). Public law protects rights, but also values and interests, including the public interest. This allows for an ecocentric standpoint; not just an anthropocentric one”.

Conclusion

The climate emergency is probably the greatest challenge of our time and the ICJ’s Advisory Opinion marks a milestone in the development of international law regarding climate change by affirming the binding character of state obligations. The ICJ’s recognition of the interrelationship between environmental protection and human rights also has the potential to open new avenues for climate litigation both internationally and domestically.

Although not binding on states, advisory opinions of the ICJ carry significant legal weight as authoritative interpretations of international law. Reference has already been made to the Advisory Opinion in domestic proceedings, including an appeal against the South African Government’s decision to authorise an offshore oil and gas project a week after its publication. It remains to be seen what impact the Advisory Opinion will have in dualist systems such as the UK, where international law is not automatically incorporated into domestic law. However, it is expected that we will see increasing reference to the ICJ’s Advisory Opinion in strategic litigation before the UK Courts as public law has an important role to play in forcing action on climate change. As Elizabeth Fisher eloquently writes in a recent article in the Journal of Environmental Law: “public law can provide the institutional and reasoning capacity for the processes required for the ‘wide-ranging, large-scale, rapid and systemic transformation’ that responding to climate change requires”.[6]

This blog post was prepared with contributions from members of our legal team including: Öykü Aktaş, Unkha Banda and Emily Soothill. It is for general information and is not intended to be used as legal advice.

[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, p. 122 https://www.ipcc.ch/report/ar6/syr/downloads/report/IPCC_AR6_SYR_FullVolume.pdf

The ICJ also notes that IPCC’s definition is consistent with the definition in Article 1(2) of the United Nations Framework Convention on Climate Change: “a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”.

[2] The Court made references to African Court on Human and Peoples’ Rights, La LIDHO, Le MIDH, La FIDH & others v. Republic of Côte d’Ivoire (2023) Application No. 041/2016, paras. 175-186; European Court of Human Rights (2024) Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, Grand Chamber, Application No. 53600/20, paras. 436 and 542; Inter-American Court of Human Rights (2023) La Oroya Population v. Peru, Preliminary Objections, Merits, Reparations and Costs, Series C No. 511, p. 54, para. 143, Human Rights Committee (2022), Daniel Billy and others v. Australia (Torres Strait Islanders Petition) CCPR/C/135/D/3624/2019.  

[3] Human Rights Committee (2019) Teitiota v. New Zealand, CCPR/C/127/D/2728/2016, para. 9.11. ICJ Advisory Opinion, para. 378.

[4] European Court of Human Rights (2024) Verein KlimaSeniorinnen Schweiz and Others v. Switzerland, Grand Chamber, Application No. 53600/20, para. 436.

[5] Inter-American Court of Human Rights (2025) Advisory Opinion, paras. 298-304.

[6] ‘Telling Meaningful Stories About Climate Change and Public Law’, Journal of Environmental Law, Volume 37, Issue 1, March 2025, Pages 1–22, https://doi.org/10.1093/jel/eqae028

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