Anticipating ICJ Advisory Opinion on Climate Change

By Elena Kosolapova, SDG Knowledge Hub

Having concluded the public hearings in the advisory proceedings on obligations of States with respect to climate change, the International Court of Justice (ICJ) – the principal judicial organ of the UN – is deliberating what many see as a landmark case, both for the Court and for climate law and action. As we wait for the advisory opinion to be delivered in open court, the date of which will be announced in due course, at the SDG Knowledge Hub, we provide answers to some of your burning questions about this historic process.

1. What are the origins of the request for an ICJ advisory opinion?

The request originated from Pacific youth who, frustrated with the slow pace of climate negotiations, lobbied governments and civil society worldwide to advocate for legal action on climate change. This grassroots movement paved the way for the small Pacific island State of Vanuatu to lead a coalition of 132 nations, calling for the UN General Assembly (UNGA) to seek a non-binding advisory opinion from the ICJ that would clarify States’ obligations under international law to protect the rights of present and future generations against the adverse effects of climate change. Ultimately, these efforts bore fruit. On 29 March 2023, the UNGA adopted by consensus Resolution 77/276, requesting the advisory opinion.

2. What are the questions before the Court?

In its request for an advisory opinion, the UNGA asked the Court two questions:

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 greenhouse gas (GHG) emissions for States and for present and future generations?
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:
- States, including small island developing States (SIDS), 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?
- Peoples and individuals of the present and future generations affected by the adverse effects of climate change?

3. Who participated in the proceedings?

In a testament to the importance the international community attaches to the advisory opinion, numerous countries and admitted organizations filed written submissions and made oral statements before the Court. By the deadline of 22 March 2024, the ICJ received 91 written statements – the highest number of written submissions ever to have been filed in advisory proceedings before the Court, as well as 62 written comments on those statements submitted subsequently.

The oral hearings were held at the seat of the Court in The Hague, the Netherlands, from 2-13 December 2024. During the hearings, those who had submitted written statements – and those who had not – were able to present their views on States’ obligations under international law and on legal consequences that apply following breach of these obligations. The Court heard a total of 96 oral statements from States and 11 from admitted organizations, many of which had also filed written statements.

4. What arguments did the Court hear?

In their oral arguments, States and admitted organizations reflected on the role of the UNFCCC, the Paris Agreement on climate change, and other environmental treaties in defining the scope of States’ obligations. They discussed human rights law, customary international law, and general principles of international law. The point in time at which knowledge of the adverse impacts of GHG emissions gave rise to States’ duty of due diligence to prevent harm to the environment was hotly debated.

The hearings revealed diverging perspectives on the legal consequences of breaching climate change-related obligations. Some underscored the climate regime’s non-punitive approach to compliance, while others emphasized the customary law of State responsibility, including obligations to cease wrongful conduct and provide reparations.

At the conclusion of the hearings, the judges invited written responses to their questions regarding: fossil fuel production; the interpretation of mitigation obligations under the Paris Agreement; the right to a healthy environment; and declarations related to State responsibility and liability for loss and damage. States and admitted organizations provided 65 written replies to the judges’ questions.

5. What is at stake?

While the ICJ’s advisory opinions are not binding, they carry significant legal weight and authority. The Court’s ruling is expected to provide a clear legal benchmark with respect to countries’ climate change-related obligations, removing any perceived ambiguities surrounding them. Legal clarity, in turn, would help strengthen the international climate regime. Many see the advisory opinion playing a role in helping accelerate redress of loss and damage, pin down a fast mitigation target, support climate justice and human rights, and course correct on SDG implementation.

Have more questions? Find answers by reading the SDG Knowledge Hub’s coverage of the ICJ advisory opinion process, including news stories, policy briefs, and guest articles by government representatives, legal counsel, and eminent scholars, among other experts.

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This Policy Brief is part of a project that seeks to raise awareness and build momentum and knowledge around the ICJ advisory opinion on obligations of States in respect of climate change and to promote a better understanding of the implications of the advisory opinion among sustainable development decision makers.