The International Tribunal of the Law of the Sea (ITLOS) was established by the United Nations Convention on the Law of the Sea (UNCLOS) to resolve disputes related to the interpretation and application of UNCLOS.
On 12 December 2022, the Commission of Small Island States on Climate Change and International Law (COSIS) submitted a request for an advisory opinion from ITLOS. In essence, COSIS asked the Tribunal to clarify the obligations of State Parties to the UNCLOS:
(a) to prevent, reduce and control pollution of the marine environment in relation to the deleterious effects that result or are likely to result from climate change, including through ocean warming and sea level rise, and ocean acidification, which are caused by anthropogenic greenhouse gas emissions into the atmosphere.
(b) to protect and preserve the marine environment in relation to climate change impacts, including ocean warming and sea level rise, and ocean acidification.
From 11 September 2023 to 25 September 2023, the Tribunal heard legal arguments from 36 States and 4 Intergovernmental organizations. They presented their views on the scope of state legal obligations with regard to climate change.
Notably, the Parties discussed whether greenhouse gas emissions should be classified as marine pollution under UNCLOS. While most States supported this view, China and India dissented. Additionally, the Parties stressed the need to align State duties with the latest scientific knowledge. Differences arose in interpreting State duties under UNCLOS: some favored a harmonious approach with other international standards, while others preferred defining these duties in accordance with the Paris Agreement and the UN Framework Convention on Climate Change.
The hearings at ITLOS hold significant importance as they could constitute a key source informing the preparation of the advisory opinions requested from the Inter-American Court of Human Rights and the International Court of Justice, which also pertain to States’ obligations with respect to climate change. Indeed, on 9 January 2023, Colombia and Chile submitted a request to the Inter-American Court of Human Rights for an advisory opinion on the Climate Emergency and Human Rights. Just a few months later, on 29 March 2023, the General Assembly of the United Nations also submitted a request for an advisory opinion, this time to the International Court of Justice, on the scope of State obligations to ensure the protection of the climate system.