Balancing Global Responsibilities: IPCC Scenarios and State Responsibility at the International Tribunal of the Law of the Sea

The International Tribunal for the Law of the Sea is a judicial body established to adjudicate disputes and provide advisory opinions on issues related to the interpretation and application of the United Nations Convention on the Law of the Sea. On December 12, 2022, the Tribunal was requested to provide an advisory opinion by the Commission of Small Island States on Climate Change and International Law. The request arose from the pressing concerns of small island states disproportionately affected by climate change, particularly rising sea levels. The case engendered wide engagement, with 30 State Parties to the Convention, the European Union, and eight Intergovernmental Organizations submitting written statements that contributed to the proceedings.

On June 28, 2023, ITLOS handed down its advisory opinion. This landmark opinion addressed key questions on State responsibility for greenhouse gas emissions, the classification of such emissions as marine pollutants, and the broader implications for international environmental law. The Tribunal’s reliance on IPCC projections underscores the importance of scientific data in shaping legal norms that address global challenges like climate change. That said, the opinion could have been strengthened by a more thorough consideration of regional differences in observed and projected sea level rise and a deeper engagement with the uncertainties inherent in sea level rise projections, among other factors. As climate impacts continue to unfold, future legal decisions on State responsibility, including domestic decisions within the United States, may build on this precedent across multiple domains.