State Obligations under UNCLOS in Relation to Climate Change and its Devastating Effects on the Sea

This article examines the Advisory Opinion (No. n. 31 of 21 May 2024) of the International Tribunal for the Law of the Sea (ITLOS), requested by the Commission of Small Island States on Climate Change and International Law (COSIS). This decision deals with environmental protection obligations of the States Parties to the 1982 Convention on the Law of the Sea (UNCLOS) (Part XII). This Opinion is the first issued by an international court/tribunal in the field of climate change, while both the advisory-opinion procedures before the Inter-American Court of Human Rights and the International Court of Justice are still pending. This article deals with the pivotal aspects of the Opinion, such as the jurisdiction of the Hamburg Tribunal and its competence to issue an advisory opinion on climate change; the definition of marine pollution under UNCLOS; the concept of necessary measures for the prevention, reduction and control of marine environmental pollution resulting from climate change; the obligation on States to exercise “stringent due diligence”; and – in particular – the express legal qualification of climate change as a common concern of humankind