International Court of Justice Affirmatively States Countries' Unambiguous Duties concerning Climate Change Responsibilities
International Court of Justice Confirms States' Legal Obligations to Combat Climate Change
In a historic ruling, the International Court of Justice (ICJ) has confirmed that states have a legally binding obligation under international law to protect the climate system. The ICJ's advisory opinion, issued in July 2025, emphasises the need for states to reduce greenhouse gas emissions, cooperate, and limit global warming to 1.5°C above pre-industrial levels.
The ICJ's decision is based on a comprehensive analysis of the entire corpus of international law, including the Charter of the United Nations, the UNFCCC, the Kyoto Protocol, the Paris Agreement, UNCLOS, international human rights law, customary international law relating to climate change, and other environmental treaties.
The ruling underscores states' due-diligence obligation to regulate private actors, preventing, mitigating, and remedying climate harm. In setting their Nationally Determined Contributions (NDCs), parties must exercise due diligence so that, collectively, their commitments can limit warming to 1.5°C and stabilize greenhouse-gas concentrations at a level that prevents dangerous human-induced interference with the climate system.
Principles such as sustainable development, common but differentiated responsibilities and respective capabilities, equity, intergenerational equity, and the precautionary approach are also considered guiding principles that are part of the applicable law.
The consequences of climate change are severe and far-reaching, affecting both natural ecosystems and human populations. Climate change is an "urgent and existential threat" to humanity. The ICJ's opinion serves as a powerful tool in strategic legal proceedings before domestic and regional courts worldwide.
The ICJ recognises the human right to a "clean, healthy and sustainable" environment, which is a prerequisite for enjoying foundational rights such as life, health, food, water, and housing. The ICJ also affirms that greenhouse gas emissions are "unequivocally caused by human activities."
The ICJ's advisory opinion is hailed as a pivotal shift for climate negotiators and litigators. It confirms that under the Paris Agreement, parties incur binding obligations to provide financial assistance, technology transfer, and capacity-building to vulnerable states.
The UN General Assembly (UNGA) Resolution A/77/L.58, initiated by the Pacific Island nation of Vanuatu and jointly sponsored by 132 developed and developing countries, formally requested this advisory opinion from the ICJ. The ICJ's opinion addresses the major legal inquiries in resolution 77/276, which broadly asked about states' obligations under international law to ensure the protection of the climate system against anthropogenic climate change and the legal consequences for states if they fail to fulfil those obligations.
| Aspect | Details | |--------------------------------------------|---------------------------------------------------------------------------------------------------------| | Core ruling | States legally obliged to reduce emissions, protect climate, cooperate, and limit warming to 1.5°C | | Legal basis | Various environmental treaties (Paris Agreement, Kyoto Protocol, etc.), human rights treaties, and customary international law | | Obligations | Due diligence, progressive climate commitments, adaptation, technology and financial cooperation | | Legal consequences for breach | Cessation of wrongful conduct, guarantees of non-repetition, reparations | | Nature of obligations | Erga omnes (common interest of all States) | | UNGA questions addressed | 1) States’ international law obligations to protect climate system; 2) Legal consequences of breach of these obligations |
This advisory opinion marks a landmark judicial pronouncement reinforcing the legal duties of states to act ambitiously and cooperatively against climate change. The ICJ's ruling underscores that these duties flow from treaty obligations (e.g., UNFCCC, Paris Agreement) and customary international law, including a right to a clean, healthy, and sustainable environment. The ICJ holds that states failing to honour their climate obligations commit an internationally wrongful act, with corresponding legal consequences. The ICJ advisory opinion affirms the entirety of Vanuatu's submissions and is hailed as a historic turning point in climate justice and accountability. The ICJ also stresses that even if an entire landmass of a Small Island State is lost, the state should still be presumed to continue as a legal entity. The ICJ advisory opinion advances the cause of climate justice. Finally, the ICJ determines that any breach of obligations related to loss and damage from climate change must be assessed under the established customary international law rules on state responsibility. The ICJ opinion rejects the theory of climate-treaty exceptionalism, affirming that climate treaties neither displace nor exhaust states' wider obligations under general international law and other treaty laws.
- The International Court of Justice (ICJ) confirmed that states have a legally binding obligation under international law to protect the climate system, limiting global warming to 1.5°C above pre-industrial levels.
- The ICJ's ruling is based on a comprehensive analysis of various environmental treaties, human rights treaties, and customary international law.
- States are obligated to reduce greenhouse gas emissions, cooperate, and take due diligence in setting their Nationally Determined Contributions (NDCs) under the Paris Agreement.
- The ICJ recognizes the human right to a "clean, healthy and sustainable" environment, which is essential for fundamental rights like life, health, food, water, and housing.
- Climate change poses severe threats to both natural ecosystems and human populations, being an "urgent and existential threat" to humanity.
- The ICJ's opinion on climate change serves as a powerful tool in strategic legal proceedings before domestic and regional courts worldwide.
- The ICJ advisory opinion holds states accountable for climate change-related wrongful acts, incurring binding obligations to provide financial assistance, technology transfer, and capacity-building to vulnerable states.
