On May 21, 2024, the court for the world’s oceans became the first international court to declare that States have a legal duty to protect the oceans from the drivers and impacts of climate change. In its landmark advisory opinion (AO), the International Tribunal for the Law of the Sea (ITLOS) confirms that greenhouse gas (GHG) emissions are a form of marine pollution that States must prevent, reduce, and control. The AO clarifies the obligations of State Parties to the United Nations Convention on the Law of the Sea (UNCLOS) in the context of the climate emergency, and makes clear that State obligations to act on climate extend beyond those under the United Nations Framework Convention on Climate Change (UNFCCC) and its Paris Agreement. This lays the foundations for future judicial pronouncements on climate duties and raises the bar for future policy decisions on climate action.

The Path to the ITLOS Climate Advisory Opinion

This historic moment was the culmination of a process initiated in 2022 by the Commission of Small Island States on Climate Change and International Law (COSIS), a coalition of Small Island Developing States (SIDS) that, despite contributing the least to anthropogenic climate change, are among those most vulnerable to its impacts. In its request for an advisory opinion, COSIS asked ITLOS to clarify:

(1) the obligations of State Parties to UNCLOS to prevent, reduce, and control anthropogenic greenhouse gas emissions as the primary driver of climate change, ocean acidification, and related harms to the marine environment; and 

(2) the obligations of State Parties to affirmatively protect and preserve the marine environment from such harms. 

The AO process drew the unprecedented participation of more than fifty States, international organizations, and civil society organizations (including CIEL), who weighed in through written submissions and/or oral interventions.

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Anthropogenic GHG emissions constitute “pollution of the marine environment.” This finding, a necessary precondition to trigger States’ duties under UNCLOS to protect and preserve the marine environment in the context of climate change, is consistent with the position taken by almost all of the State delegations to the advisory proceedings, with the notable exceptions of India and China. ITLOS affirmed that anthropogenic GHG emissions are a form of marine pollution since, per Article 1 of UNCLOS, they result in “substances” (i.e., carbon dioxide) and “heat” entering the marine environment, which then leads to “deleterious effects” such as ocean warming, sea level rise, and ocean acidification. States have a duty to take all measures necessary to “prevent, reduce, and control” such pollution, whether it stems from land-based sources, vessels, or aircraft. 

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States must be guided by the best available science. Throughout its AO, ITLOS recognizes the centrality of science to the questions before it, and notes that “with regard to climate change and ocean acidification, the best available science is found in the works of the Intergovernmental Panel on Climate Change which reflect the scientific consensus.” The Tribunal calls for State action to take into account “the global temperature goal of limiting the temperature increase to 1.5°C above pre-industrial levels and the timeline [under the Paris Agreement] for emission pathways to achieve that goal.” 

Upasana Khatri, Center for International Environmental Law, 27 June 2024. Full article.

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