Request for an Advisory Opinion submitted by the Commission of Small Island States on Climate Change and International Law

On December 12, 2022, the Co-Chairs of the Commission of Small Island States on Climate Change and International Law (the Commission), representing the Commission pursuant to Article 3(3) of the Agreement for the Establishment of the Commission, submitted a request for an advisory opinion from the International Tribunal for the Law of the Sea (the "Tribunal") on the legal questions set out below. The Commission referred the following legal questions to the Tribunal for an advisory opinion: What are the specific obligations of State Parties to the United Nations Convention on the Law of the Sea (the "UNCLOS"), including under Part XJI: (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? States concerned: Antigua & Barbuda, Vanuatu, Tuvalu, Nieu, St. Lucia, Palau. As fixed by the order, the deadline to submit briefs was June 16th, 2023. By that date, 31 states and eight intergovernmental organizations submitted written statements pursuant to article 138 paragraph 3 and article 133 paragraph 3 of the Rules of the Tribunal. Ten additional groups submitted written statements not pursuant to these articles. Rwanda and the Food and Agricultural Organization of the United Nations (FAO) submitted statements after the due date. On May 21, 2024, the Tribunal issued a unanimous advisory opinion. Among other things, the Tribunal concluded that States Parties to UNCLOS must "take all necessary measures to prevent, reduce, and control marine pollution from anthropogenic GHG emissions.” The Tribunal held that anthropogenic GHG emissions into the atmosphere constitute “pollution of the marine environment” within the meaning of article 1, paragraph 1, subparagraph 4, of UNCLOS. In reaching this decision, the tribunal noted that the definition of “marine pollution” in UNCLOS contains three element: (1) there must be a substance or energy; (2) this substance or energy must be introduced by humans, directly or indirectly, into the marine environment; and (3) such introduction must result or be likely to result in deleterious effects (para. 161). The tribunal found that anthropogenic GHG emissions met each of these criteria because, “through the introduction of carbon dioxide and heat (energy) into the marine environment, anthropogenic GHG emissions cause downstream climate change and ocean acidification, which results in the deleterious effects illustrated in the definition of pollution of the marine environment.” (para. 178). With regards to pollution control measures, the Tribunal found that under article 194, paragraph 1 of UNCLOS, “States Parties to the Convention have the specific obligations to take all necessary measures to prevent, reduce and control marine pollution from anthropogenic GHG emissions and to endeavour to harmonize their policies in this connection” (para. 243). The obligation to take all necessary measures is a “due diligence” obligation, which requires States to put in place a national system to regulate polluting activities and to exercise vigilance to ensure the effectiveness of that system (para. 235). The Tribunal found that, in the context of GHG emissions, the due diligence standard “is stringent, given the high risks of serious and irreversible harm to the marine environment from such emissions” (para. 243). The due diligence standard may also vary in accordance with State capabilities and available resources, as States with greater capabilities and resources may be required to do more than States with lesser means. However, the Tribunal notes that even a State with fewer capabilities and resources must “do whatever it can in accordance with its capabilities and available resources to prevent, reduce and control marine pollution from anthropogenic GHG emissions” (para. 241). The Tribunal also found that article 192 of UNCLOS “imposes a general obligation on States Parties to protect and preserve the marine environment” (para. 400). This obligation “applies to all maritime areas and can be invoked to combat any form of degradation of the marine environment, including climate change impacts, such as ocean warming and sea level rise, and ocean acidification” (para. 400). The obligation “may include restoring marine habitats and ecosystems” where the marine environment has been degraded (emphasis added) (para. 386). Moreover, the obligation to take measures necessary to protect and preserve the marine environment mandates that States ensure non-State actors under their jurisdiction or control adhere to these measures (para 396). Similar to the obligation to prevent, reduce, and control pollution, the obligation involves a due diligence standard, with similar contours as described above.