The International Tribunal for the Law of the Sea (ITLOS) under the United Nations Convention on the Law of the Sea (UNCLOS) issued a landmark advisory opinion on May 21, 2024, that classified greenhouse gases (GHGs) as marine pollutants. The advisory opinion, which the Commission of Small Island States (COSIS) has been pursuing since December 2022 [1], is a significant milestone in the battle against climate change and has far-reaching implications for the future of Small Island Developing States (SIDS), international climate policies, and litigation.
The advisory opinion issued by ITLOS establishes strong obligations for State Parties under UNCLOS and provides legal clarity on the status of GHGs as marine pollutants. It acknowledges the critical role of GHGs in the marine environment and the impact of climate change, such as ocean acidification, sea-level rise, and ocean warming [2]. Advisory opinions aren’t binding but carry significant weight due to the authority of the issuing court, and decisions to endorse them are often recognised as valid under international law [3].
According to the Tribunal, simply adhering to the obligations of the Paris Agreement is not sufficient to satisfy the requirements of the Convention [4]. The Paris Agreement upholds the Convention’s goal of controlling anthropogenic GHGs that cause marine pollution, but it does not take precedence over it. In the Tribunal’s opinion, the Paris Agreement is not lex specialis (not a special rule that takes precedence) to the Convention [5].