OBLIGATIONS OF STATES IN RESPECT OF CLIMATE CHANGE (REQUEST FOR ADVISORY OPINION) [2025] ICJ REP (23 JULY 2025)

Case Name: OBLIGATIONS OF STATES IN RESPECT OF CLIMATE CHANGE (REQUEST FOR ADVISORY OPINION) [2025] ICJ REP_ (23 JULY 2025)

CASE INFORMATION

FACTS

The request for an advisory opinion arose amid growing international concern over the accelerating impacts of climate change. Rising global temperatures have contributed to the melting of glaciers and polar ice sheets, resulting in sea-level rise that threatens coastal regions and the very existence of many Small Island Developing States (SIDS). Climate change has also intensified extreme weather events, including hurricanes, droughts, floods, and heat waves, causing displacement, food and water insecurity, and extensive environmental degradation. These impacts have disrupted ecosystems, accelerated biodiversity loss, and increased risks to public health through heat-related illnesses and climate-sensitive diseases. In evaluating the request, the International Court of Justice relied on scientific assessments of the Intergovernmental Panel on Climate Change (IPCC), which indicated that climate-related risks become significantly more severe if global warming exceeds 1.5°C, with even greater consequences at 2°C or above.

These escalating impacts, particularly on vulnerable Small Island Developing States such as Vanuatu, underscored the need for authoritative clarification of States’ obligations under international law, ultimately leading to the request for an advisory opinion from the International Court of Justice.

PROCEDURAL HISTORY

The procedural journey of ICJ’s advisory opinion on climate change evolved from a grassroots student movement into a historic UN mandate. In March 2019, 27 law students from the Pacific Islands Students Fighting Climate Change (PISFCC) launched a campaign in Vanuatu, demanded to use world’s highest court to clarify States’ climate obligations. The Government of Vanuatu adopted the students’ proposal and began building a global diplomatic coalition to sponsor a UN resolution. On March 29, 2023, the United Nations General Assembly (UNGA) unanimously adopted a resolution formally requesting an advisory opinion from the ICJ, and submitted questions to the Court. Then after, the Court opened the floor for written statements, resulting in 91 written submissions from countries and international bodies. The first oral hearing held by ICJ at the Peace Palace in The Hague, in late 2024.On finally, on July 23, 2025, the ICJ officially delivered its final Advisory Opinion, led by Court President Yuji Iwasawa, the 15 Judges Panel. Following the ruling, Vanuatu spearheaded a follow-up UN General Assembly resolution in May 2026, to formally adopt the ICJ’s finding.

QUESTION REFERRED BY THE UNITED NATIONS GENERAL ASSEMBLY.

The General Assembly requested the Court to render an advisory opinion on the following questions:

(1) 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?

(2) 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?

The Court received written and oral submissions from an unprecedented number of States and international organizations. While participants differed on the scope of States’ obligations and the legal consequences of climate change, there was broad agreement on the need for clarification of international law. The Court considered these submissions in formulating its advisory opinion.

APPLICABLE INTERNATIONAL LAW

• The court exercised its jurisdiction under article 65 of the statute of the International court of justice, following a request made by the United Nations general assembly under article 96 of the UN charter.
• In determining the obligations of States regarding climate change, the Court relied on various sources of international law. It referred to Articles 1, 55, and 56 of the United Nations Charter (1945), which establish the duty of States to cooperate in addressing global challenges, including environmental protection.
• The Court also relied on the United Nations Framework Convention on Climate Change (UNFCCC), 1992, the principal international treaty governing cooperation on climate change. It further considered the Paris Agreement (2015), particularly the commitments of States to limit the rise in global temperatures and progressively strengthen their climate actions through Nationally Determined Contributions (NDCs).
• In addition, the Court referred to international human rights law, recognising that climate change poses serious risks to the enjoyment of fundamental human rights, including the rights to life, health, and an adequate standard of living, as well as the interests of future generations.
• Furthermore the court considered key principles of due diligence, prevention of significant transboundary environmental harm, and international cooperation established through the customary International Law.

COURT ANALYSIS AND REASONING

The Court interpreted these instruments together and concluded that States have legally enforceable obligations to exercise due diligence, cooperate internationally and take effective measures to prevent significant harm to the climate system.

1. Climate Change as an Urgent Global Concern

After considering the written statements submitted by States and international organizations, the Court recognised climate change as an urgent and existential threat to humanity and the environment. It emphasised that addressing climate change requires collective international cooperation based on scientific evidence, particularly the findings of the Intergovernmental Panel on Climate Change (IPCC).

2. Obligations of States under International Law

In interpreting the obligations of States, the Court held that international law imposes a duty on every State to protect the climate system. It observed that States must adopt appropriate legislative, administrative, and policy measures to prevent environmental harm and fulfil their climate commitments. The Court further emphasised that States have a continuing duty to cooperate internationally in achieving the shared objective of protecting the climate system and ensuring a safe, clean, healthy, and sustainable environment.

3. Human Rights and Climate Change

The Court further recognised the close relationship between climate change and the protection of human rights. It observed that the adverse effects of climate change threaten the enjoyment of fundamental rights, including the rights to life, health, food, water, and an adequate standard of living. The Court also acknowledged that climate action must take into account the interests of present and future generations.

4. State Responsibility

The Court also examined the legal consequences arising from a breach of international climate obligations. It held that where the conditions for State responsibility are satisfied, a State may incur international responsibility for its internationally wrongful acts or omissions. Such responsibility may give rise to legal consequences in accordance with the applicable rules of international law.

5. Interpretation of the Paris Agreement

The Court rejected the view that the Paris Agreement merely contains political commitments. Instead, it held that Parties have legally binding obligations to prepare, communicate, and maintain their Nationally Determined Contributions (NDCs). The Court further emphasised that these obligations must be implemented in good faith.

HOLDING (ADVISORY OPINION) AND RATIO DECIDENDI

Holding (Advisory Opinion)

On 23 July 2025, the International Court of Justice delivered its Advisory Opinion in response to the questions referred by the United Nations General Assembly. The Court unanimously affirmed that States have binding obligations under international law to protect the climate system and other parts of the environment from anthropogenic greenhouse gas emissions. These obligations arise from international treaties, customary international law, and relevant principles of international environmental and human rights law.

The Court further held that where a State, through its acts or omissions, breaches these obligations and the conditions of State responsibility are met, it may incur international responsibility. Depending on the circumstances, such responsibility may require the State to cease the wrongful conduct, offer appropriate assurances of non-repetition, and make full reparation in accordance with international law.

Besides confirming this legal obligation for ambitious action on the climate crisis, the court affirmed that the goal of limiting global warming to 15^oC, as enshrined in the Paris Agreement, is legally binding.     

Ratio Decidendi

The Court’s decision is founded on the principle that climate change is not solely an environmental issue but a matter governed by binding rules of international law. States have a continuing duty to exercise due diligence, cooperate in good faith, and take effective measures to prevent significant harm to the climate system. Failure to fulfil these obligations may constitute an internationally wrongful act, giving rise to legal consequences under the law of State responsibility.

CRITICAL ANALYSIS AND SIGNIFICANCE

The Advisory Opinion marks a significant development in international environmental law by clarifying that States’ obligations to address climate change are rooted in binding rules of international law rather than political commitments alone. Although advisory opinions are not legally binding, they carry substantial legal and persuasive authority and are likely to influence domestic courts, international tribunals, and future climate-related litigation.

A major strength of the Opinion is its integration of international environmental law, human rights law, and the law of State responsibility into a coherent legal framework. By recognising the relationship between climate change and the enjoyment of fundamental human rights, the Court reinforced the principle that environmental protection is closely connected with human dignity and sustainable development.

The Opinion is also significant for vulnerable States, particularly Small Island Developing States (SIDS), whose concerns were central to the request for the Advisory Opinion. It strengthens their legal position in international negotiations and future claims concerning climate-related harm.

However, certain limitations remain. As an advisory opinion, it does not impose direct legal sanctions or determine the liability of any particular State. Questions relating to causation, attribution of emissions, and the assessment of reparations will continue to depend on the facts of individual cases. Consequently, the practical implementation of the Court’s guidance will largely depend on the willingness of States and other international institutions to act consistently with the principles articulated by the Court.

Overall, the Advisory Opinion represents a landmark contribution to the progressive development of international climate law and is expected to shape future State practice, judicial decisions, and international climate governance.

CONCLUSION

The Advisory Opinion on Obligations of States in Respect of Climate Change marks a significant milestone in the development of international climate law. By clarifying that States have legally binding obligations to protect the climate system under international law, the International Court of Justice has strengthened the legal framework governing global climate action. The Opinion also reinforces the close relationship between environmental protection, human rights, and the principle of State responsibility.

Although the Advisory Opinion is not legally binding, its authoritative interpretation of international law is expected to influence future judicial decisions, international negotiations, and domestic climate litigation. It provides valuable guidance to States in fulfilling their climate obligations while promoting greater international cooperation and accountability. As climate change continues to pose unprecedented global challenges, this Opinion will remain a landmark reference in shaping the future of international environmental law.

Reference(S):

1. International  court of Justice, summary 2025/4: Obligation of states in respect of climate change (Request of Advisory opinion) (23 July 2025)
2. United Nation General Assembly, Request for an advisory opinion of the International court of Justice on the obligations of states in respect of climate change, UNGA Res 77/276 (29 march 2023).
3. Soenke Kreft and Maren Solmecke, ‘Delivering Climate Justice? The ICJ Advisory Opinion and its Significance for Climate Action’ (United Nations University, 28 July 2025) United Nations University accessed 7 July 2026.