ITLOS issues its groundbreaking advisory opinion on marine pollution caused by greenhouse gases: implications for States, legislators and private actors

On 21 May 2024, the International Tribunal for the Law of the Sea (“ITLOS”) issued its much anticipated advisory opinion on the obligations of States to preserve and protect the world’s oceans from the impacts of climate change (“Opinion”). The Opinion was requested by a coalition of nine island nations, the Commission of Small Island States on Climate Change and International Law (“COSIS”), in December 2022, to clarify the specific environmental obligations of State Parties to the United Nations Convention on the Law of the Sea (“UNCLOS”) in relation to climate change-related impacts on oceans.

In the Opinion, the ITLOS has for the first time held that greenhouse gas emissions (“GHG emissions”) absorbed by the world’s oceans constitute marine pollution under the terms of the UNCLOS, and over 160 countries that are party to UNCLOS are obliged to protect and preserve the marine environments by taking all necessary, specific and concrete steps to prevent, reduce and control pollution of the marine environment by GHG emissions, including going beyond and in addition to the scope of the responsibilities of States under the Paris Agreement.

Key points

• The Opinion will likely influence and bolster international and domestic policies and law in relation to climate change (in particular, those aimed at reducing GHG emissions from a range of sources) and guide States in their climate change policies – in particular in relation to how States must assist each other in responding to climate change.
• Notably, the ITLOS has recognised the responsibility of State Parties to regulate private actors in mitigating and preventing climate change-related impacts. The Opinion will likely provide stronger impetus for States to introduce laws/policies to regulate business activities and to include stringent due diligence and other legal obligations for businesses.
• The Opinion is an important reminder for commercial parties to try to anticipate the likelihood of climate change-related regulatory changes and review proactively their own operations and policies, as part of managing their own risk in the increasingly complex climate litigation context. In particular, commercial parties can consider how these align with available international scientific standards and climate change treaties.
• The Opinion is the first of several international advisory opinions expected in the coming months from international law bodies, namely those pending before the International Court of Justice and Inter-American Court of Human Rights, all of which seek to clarify the position under international law on States' obligations in relation to climate change. We can expect that the ITLOS’ findings are likely to affect how other international courts and tribunals, as well as national courts, address issues relating to climate change, particularly with respect to pollution caused by GHG emissions and the obligations of States (and other actors) to prevent, reduce and control such pollution.

More details on the ITLOS’ findings in the Opinion and an analysis of what this is likely to mean for the development of international practice and treaties, domestic legislation and broader impacts including on private actors, can be found in our latest client briefing, which can be accessed here.