Request for an Advisory Opinion Submitted by the Commission of Small Island States on Climate Change and International Law, Case 31

Abstract On 21 May 2024, the International Tribunal on the Law of the Sea ( ITLOS ) delivered a ground-breaking and authoritative advisory opinion on States’ obligations under Part XII of the 1982 United Nations Convention on the Law of the Sea ( LOSC ). After confirming its jurisdiction over the request, ITLOS ruled that greenhouse gas emissions cause ‘deleterious effects on the marine environment’ and therefore constitute pollution under the LOSC. ITLOS explained the relationship between obligations under the LOSC and climate law and clarified the due diligence nature of the LOSC obligations to prevent marine pollution and to protect the marine environment.