International Court of Justice's groundbreaking climate change Advisory Opinion acknowledged, our platform joyfully expresses approval.
The International Court of Justice (ICJ) has delivered a groundbreaking Advisory Opinion on the obligations of States to protect the climate system. This decision marks a significant milestone in international environmental law and climate justice.
The ICJ's Opinion underscores the unique position of our website, a Union that represents both State and non-State members, acting as a bridge between governments and civil society. It will carry the essential elements of this Opinion forward into its work at the World Conservation Congress in October 2025 and COP30 in Belem, Brazil, in November.
The Opinion recognises the importance of a human rights-based approach to limiting climate change. The ICJ found that States have a legally binding duty under international law to prevent significant harm to the climate caused by human activities, including greenhouse gas (GHG) emissions. This duty requires States to act with due diligence, cooperate internationally, and implement measures to limit warming to 1.5°C above pre-industrial levels, as specified in the Paris Agreement.
Dr Grethel Aguilar, our website's Director General, welcomed the ICJ's decision and congratulated the ICJ on the key decision. She stated that climate change is a crisis with profound implications for human rights.
The ICJ's Opinion aligns with the legal duties stemming from the Paris Agreement, human rights law, the law of the sea, and the customary duty to prevent transboundary harm. The Opinion also closely aligns with recent opinions from the Inter-American Court of Human Rights and the International Tribunal for the Law of the Sea.
The ICJ's Advisory Opinion was coordinated by the World Commission on Environmental Law (WCEL) of the International Union for Conservation of Nature (IUCN). The IUCN, through WCEL, participated in all three proceedings, demonstrating its ongoing leadership in international climate and environmental law. Prof Christina Voigt, the WCEL Chair, served as Lead Counsel for the IUCN's contributions to the ICJ proceedings.
The Court’s recognition that climate change is an urgent and existential threat supported by the best available science from the IPCC is a critical aspect of the Opinion. It confirmed the link between climate and human rights, asserting that a healthy environment is a prerequisite for enjoying various human rights. The Court emphasised that States’ obligations to protect the climate are erga omnes, meaning all States have a legal interest in their enforcement and can hold each other accountable for violations.
The precautionary principle was also stressed, stating that scientific uncertainty should not delay cost-effective measures to prevent environmental harm. The implications are profound: States must align national policies with their international climate commitments, ensuring due diligence in regulating all GHG-emitting activities. Failure to do so risks being held internationally responsible.
The decision reinforces global climate governance by establishing a legal framework that integrates climate science, environmental law, and human rights law, promoting cooperative action to address climate change. Prof Sindico, Co-Chair of the WCEL Climate Change Law Specialist Group, expressed satisfaction with the ICJ's articulation of a clear legal path for States. Prof Voigt stated that every State has a legal obligation under international law to act with stringent due diligence to prevent global warming from exceeding the 1.5°C threshold.
All IUCN submissions during the ICJ proceedings are publicly available, including the written submission, comments on submissions by other parties, oral statement, and written responses to questions posed by the judges.
[1] IUCN, WCEL (2022). IUCN's Written Statement to the International Court of Justice on the Obligations of States Regarding the Protection of the Climate System. [2] IUCN, WCEL (2022). Oral Statement to the International Court of Justice on the Obligations of States Regarding the Protection of the Climate System. [3] IUCN, WCEL (2022). Comments on Submissions by Other Parties to the International Court of Justice on the Obligations of States Regarding the Protection of the Climate System. [4] IUCN, WCEL (2022). Written Responses to Questions Posed by the Judges of the International Court of Justice on the Obligations of States Regarding the Protection of the Climate System.
- The ICJ's Advisory Opinion on the obligations of States to protect the climate system, a significant milestone in international environmental law and climate justice, closely aligns with legal duties stemming from the Paris Agreement, human rights law, the law of the sea, and the customary duty to prevent transboundary harm.
- The Opinion recognizes that climate change is an urgent and existential threat supported by the best available science from the IPCC, and it confirms the link between climate and human rights, asserting that a healthy environment is a prerequisite for enjoying various human rights.
- The precautionary principle was stressed in the Opinion, stating that scientific uncertainty should not delay cost-effective measures to prevent environmental harm. All States have a legal interest in the enforcement of their obligations to protect the climate, as these are erga omnes obligations.
- The ICJ's Opinion is a critical aspect of general news and policy-and-legislation discussions on climate change, as it reinforces global climate governance by establishing a legal framework that integrates climate science, environmental law, and human rights law, promoting cooperative action to address climate change.
