ICJ Rules on Climate Change Obligations—A Turning Point?

The International Court of Justice (ICJ) has just delivered its long-awaited advisory opinion on the country’s obligation and accountability on climate change.

On 23 July 2025, the ICJ ruled that countries are legally obliged to protect and prevent harm to the environment, and that they must take action to mitigate climate change and reduce greenhouse gas emissions.

It all began in 2019 in the Pacific Islands, when 27 law students from the University of the South Pacific in Fiji sought an advisory opinion from the ICJ on climate change due to the small island developing states’ (SIDS) vulnerability to climate change impacts and also to hold countries accountable for their GHG emissions.

These students established a youth-led grassroots organisation – dubbed the Pacific Island Students Fighting Climate Change (PISFCC)- and urged leaders of the Pacific Islands Forum to bring the issue of climate change to the ICJ, the world’s top court. 

In 2021, the Vanuatu government announced its intention to champion the initiative. Vanuatu then engaged with other countries in Europe, Asia, Africa, and Latin America to join them in their efforts to gain the ICJ’s advisory opinion.

The 105 countries that backed the resolution brought it to the United Nations. On 29 March 2023,  the UN General Assembly formally adopted a resolution and requested an advisory opinion from the ICJ. 

According to the United Nations, the authority to request an advisory opinion is only open to five organs of the United Nations and 16 specialised agencies of the UN.  While the UN General Assembly and Security Council may request advisory opinions on “any legal question”, the other UN organs and specialised agencies can only do so concerning legal questions that arise within the scope of their work or issues related to their function.  The UN General Assembly requests most advisory opinions.

The two central questions asked of the court are as follows: 

1. 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?
2. 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:
   • States, including, in particular, small island developing States, which, due to their geographical circumstances and level of development, are injured or affected explicitly by, or are particularly vulnerable to, the adverse effects of climate change?
   • People and individuals of the present and future generations are affected by the adverse effects of climate change. 

ICJ’s advisory opinion on States’ obligations in respect of climate change

The ICJ’s advisory opinion issued in The Hague, Netherlands, on the State’s obligations regarding climate change ruled that States have a responsibility to protect the environment from greenhouse gas (GHG) emissions and act with due diligence and cooperation to fulfil this obligation. This includes the obligation under the Paris Agreement on climate change to limit global warming to 1.5°C above pre-industrial levels.  

The Court further ruled that if States breach these obligations, they incur legal responsibility and may be required to cease the wrongful conduct, offer guarantees of non-repetition and make full reparation depending on the circumstances (World Court, 2025).

While the ICJ’s legal opinion is not legally binding – meaning it does not lawfully oblige countries, UN organs, or agencies to follow the advice – it still carries influence, guides decision-making, and shapes international norms.

In this opinion, the International Court of Justice (ICJ) clarifies that when countries fail to take action to protect the climate system, it constitutes a breach of the international laws to which they are obligated to follow.

The article from Carbon Brief discusses the implications of the ICJ’s legal opinion on scientific data related to climate change. It covers how the case was decided, the commitments made by countries to mitigate climate change, their ongoing violations of these commitments, and the demands from developing countries for reparations related to loss and damage.

Additionally, it addresses other critical issues surrounding the effects and impacts of climate change. The article on SEI also helps to unpack the implications of the ICJ ruling.

Various reactions to the ICJ’s Opinion

According to Carbon Brief, many governments, NGOs, and legal experts consider this a “groundbreaking” legal milestone and a “moral reckoning.” However, some governments, such as the European Union and France, have responded cautiously.

Additionally, opposition politicians in the UK have expressed negative views about it. A spokesperson from the Chinese government stated that the opinion aligns with the country’s views, while the United States emphasised that it would prioritise its own interests.