climate change litigation

The conference of parties to UNFCCC does not provide for an enforcement mechanism, meaning that States cannot be held to account for missing their targets under the Paris Agreement. Nevertheless, climate change litigation has taken off at a national, regional and now international level in recent years and the number of cases where individuals or national environmental groups have held governments or companies to account for their climate-related policies is growing quickly. UNEP issues a regular report, see the latest Global Climate Litigation Report: 2023 Status Review and the Columbia Law School, Columbia Climate School and the Sabin Center for Climate Change Law maintain a database tracking cases. Using climate attribution science, which establishes the relationship between anthropogenic emissions and specific extreme weather events, claimants are able to quantify the environmental impact of projects, policies and laws and the ensuing rulings demanding governmental action based on human rights doctrines are becoming more common. The UN Human Rights Council passed a resolution in 2021 declaring the human right to a clean environment, this was echoed by a UN General Assembly resolution in 2022 and calls to make mass environmental destruction, known as ecocide, a crime against humanity are growing, spearheaded by Stop Ecocide International.

With specific regard to the ocean, even if it doesn’t include the words ‘climate change’, Part XII of UNCLOS provides a robust framework calling on States to protect the marine environment. Article 192 includes the obligation to protect the marine environment, article 194 to prevent, reduce and control pollution, and article 197 sets down the duty to cooperate. While a State to State dispute on climate change is unlikely, the advisory opinions from the International Tribunal for the Law of the Sea and the International Court of Justice will confirm obligations on States in this regard.

ITLOS Advisory Opinion

The Commission of Small Island Developing States on Climate Change and International Law, established at COP26 in 2021 to submit a request for an advisory opinion to ITLOS, did just that in 2022, putting the following questions:

What are the specific obligations of State Parties to the United Nations Convention on the Law of the Sea (‘UNCLOS’), including under Part XII:

(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?

The Advisory Opinion was delivered by the Tribunal on 21 May 2024, concluding that anthropogenic greenhouse gas (GHG) emissions into the atmosphere do indeed constitute pollution of the marine environment within the meaning of the Convention. This conclusion therefore triggers the obligations on States Parties under article 194, paragraph 1, of the Convention, to take all necessary measures to prevent, reduce and control marine pollution from such emissions.

The Tribunal emphasised the importance of using the best available science, emphasising that States should take into account the best available science and relevant international rules and standards contained in climate change treaties such as the United Nations Framework Convention on Climate Change and the Paris Agreement, and in particular the goal of limiting temperature increase to 1.5°C above pre-industrial levels. This is the first time that the 1.5°C goal has been tied to a legal obligation to protect the marine environment by an international court. 

Looking at the Paris Agreement, the Tribunal did not consider that the obligation to prevent, reduce and control marine pollution from GHG emissions would be satisfied simply by complying with the obligations and commitments under the Paris Agreement. Considering that the Convention and the Paris Agreement are separate agreements with separate sets of obligations, a failure to comply with this obligation would engage international responsibility.

The Tribunal found that the obligation under article 194, paragraph 1, of the Convention is one of due diligence and that the standard of due diligence is stringent given the risks of serious and irreversible harm to the marine environment from anthropogenic GHG emissions. In the Tribunal’s view, the implementation of the obligation of due diligence may vary according to States’ capabilities and available resources.

The Tribunal found that, under article 194, paragraph 2, of the Convention, States Parties have the specific obligation to take all measures necessary to ensure that anthropogenic GHG emissions under their jurisdiction or control do not cause damage to other States and their environment, and that pollution from such emissions under their jurisdiction or control does not spread beyond the areas where they exercise sovereign rights. The Tribunal found that this is also an obligation of due diligence but considered that the standard of due diligence can be even more stringent than under article 194, paragraph 1. 

Looking at the obligation under article 192 of the Convention to protect and preserve the marine environment from climate change impacts and ocean acidification, it concluded that States Parties have an obligation to do so, and that this may call for measures to restore marine habitats and ecosystems. It found that States Parties have a specific obligation under article 194, paragraph 5, of the Convention to protect and preserve rare or fragile ecosystems as well as the habitat of depleted, threatened or endangered species and other forms of marine life from climate change impacts and ocean acidification.

See the case page here.

ICJ Advisory Opinion

At the instigation of Vanuatu, the UN General Assembly requested an Advisory Opinion from the ICJ in April 2023, posing the following questions:

“Having particular regard to the Charter of the United Nations, the International Covenant on Civil and Political Rights, the International Covenant on Economic, Social and Cultural Rights, the United Nations Framework Convention on Climate Change, the Paris Agreement, the United Nations Convention on the Law of the Sea, the duty of due diligence, the rights recognized in the Universal Declaration of Human Rights, the principle of prevention of significant harm to the environment and the duty to protect and preserve the marine environment,

(a) What are the obligations of States under international law to ensure the protection of the climate system and other parts of the environment from anthropogenic emissions of greenhouse gases for States and for present and future generations;

(b) What are the legal consequences under these obligations for States where they, by their acts and omissions, have caused significant harm to the climate system and other parts of the environment, with respect to:

(i) States, including, in particular, small island developing States, which due to their geographical circumstances and level of development, are injured or specially affected by or are particularly vulnerable to the adverse effects of climate change?

(ii) Peoples and individuals of the present and future generations affected by the adverse effects of climate change?”

The ICJ case is now in the second round of the written phase, during which States and relevant organizations may submit their views on the first round of submissions. Hearings at the ICJ will be held in December 2024, putting the court on course for their advisory opinion to be delivered during the course of 2025. See their case page here.

dive in deeper

Panel Discussion on ITLOS Advisory Opinion on Climate Change and International Law

A Commentary on ITLOS' Advisory Opinion on Climate Change

Opinio Juris: ITLOS Advisory Opinion on Climate Change and Oceans: Possibilities and Benefits

EJIL:The Podcast! Episode 18 – “Be Careful What You Ask For”

ASIL: International Law and Climate Change: We are All Climate Lawyers Now