The International Court of Justice (ICJ), the UN’s principal judicial body, announced the release of its Advisory Opinion on the Obligations of States in respect of Climate Change, indicating that countries have an obligation under international law to reduce greenhouse gas (GHG) emissions and to contribute to climate change adaptation, opening up potential requirements by wealthier nations to pay compensation to developing countries most affected by climate change.

The ICJ announcement follows a request by the UN General Assembly in 2023 for an advisory opinion to outline the obligations of states under international law to ensure the protection of the environment from GHG emissions, and into the legal consequences for states that cause significant climate harm “by their acts and omissions,” particularly in relation to the most impacted small island developing States, and to future generations. The UNGA request was made after the Pacific Island State of Vanuatu announced in 2021 that it would seek an advisory opinion from the court on climate change.

According to the ICJ opinion, all state parties to the United Nations Framework Convention on Climate Change (UNFCCC) – which has been ratified by all UN member states – have an obligation to adopt measures to contribute to the mitigation of GHG emissions and to adapting to climate change, while developed nations have an additional obligation “to take the lead in combating climate change by limiting their greenhouse gas emissions and enhancing their greenhouse gas sinks and reservoirs.”

The opinion also indicated that countries that are parties to the Paris Agreement have a obligation to prepare and maintain climate plans collectively enabling the agreement’s goal to limit global warming to 1.5°C above pre-industrial levels. Nearly all countries have signed the Paris Agreement, although President Trump has initiated proceedings to withdraw the U.S. from the accord.

Additional obligations highlighted by the opinion include duties for states to cooperate on achieving the UNFCCC objectives to address climate change, and for adaptation and co-operation among Paris Agreement parties, “including through technology and financial transfers, which must be performed in good faith.”

While the ICJ opinion is non-binding, according to legal experts, it could have significant consequences for wealthy nations, leading to potential suits by developing countries facing a need to adapt to the impacts of climate change.

Danilo Garrido, Legal Counsel at Greenpeace International, said:

“The ICJ advisory opinion marks a turning point for climate justice, as it has clarified, once and for all, the international climate obligations of States, and most importantly, the consequences for breaches of these obligations. This will open the door for new cases, and hopefully bring justice to those, who despite having contributed the least to climate change, are already suffering its most severe consequences.”

Image source: UN Photo/ICJ-CIJ/Frank van Beek. Courtesy of the ICJ.