The International Court of Justice (ICJ), the principal judicial organ of the United Nations (UN), commenced hearings on the obligations of States concerning climate change on Monday. The oral proceedings are scheduled from Monday, December 2, to Friday, December 13, 2024, at the Peace Palace in The Hague, Netherlands.The request for an advisory opinion from the ICJ was submitted in March 2023, following the unanimous adoption of Resolution 77/276 by the UN General Assembly. The resolution sought the court’s guidance on the obligations of States concerning climate change. This includes questions about the positive duties of States to “ensure the protection of the climate system […] for present and future generations” and the legal implications of “acts and omissions [that] have caused significant harm to the climate system.” Notably, the second question addresses the international community’s legal responsibilities toward small island developing States, which are disproportionately threatened by the adverse effects of climate change.Article 96 of the UN Charter serves as a legal basis for the UN General Assembly, Security Council, and specialized agencies to submit legal questions to the ICJ. Article 65 of the ICJ Statute further establishes the court’s jurisdiction to provide advisory opinions. Although non-binding, they serve as authoritative statements of international law.The request for an advisory opinion was initially inspired by a grassroots movement in Vanuatu and subsequently advanced by its government. This island state in the South Pacific, in collaboration with nations such as Costa Rica, Sierra Leone, Angola, Germany, the Federated States of Micronesia, Bangladesh, and others, played a key role in drafting the resolution. The adverse consequences of climate change are well recognized, yet substantial discrepancies persist in the international community’s approach to mitigating its impacts. Emissions from high-polluting countries like the US, Canada, Russia, and China have accelerated climate change’s harmful consequences, disproportionately affecting small island nations, which are particularly vulnerable due to their “geographical circumstances and level of development.” The unanimous agreement of all 193 UNGA member States to refer the request to the ICJ highlights the critical importance of addressing this global issue.Remarkably, the international community’s participation has been unprecedented, with 91 written submissions, 62 follow-up comments, and 98 States, with 12 authorized international organizations, set to engage in the oral proceedings before the ICJ in the coming weeks.While the ICJ’s advisory opinion is expected in 2025, it is not the first international judicial body to address States’ legal obligations regarding climate change. Earlier this year, the International Tribunal for the Law of the Sea issued a groundbreaking advisory opinion, urging States to reduce greenhouse gas emissions