CLIMATE CHANGE AND STATE RESPONSIBILITY IN INTERNATIONAL LAW: FROM THE DUTY TO PREVENT TO REPARATION AFTER THE ICJ'S 2025 ADVISORY OPINION

Author

Aanchal Ajit Malpani


Abstract

 Few legal problems strain the law of State responsibility as severely as climate change. The emissions behind it originate in innumerable public and private activities; they accumulate in the atmosphere across decades; and the injuries they produce frequently arise far from their point of release. Because harm of this kind is cumulative and transboundary, it has long been difficult to identify the governing international obligations, to determine whose conduct is legally relevant, to establish what caused a particular injury, and to decide whether reparation is owed.

Much of the regulatory work has been carried out by treaty, namely the United Nations Framework Convention on Climate Change, the Kyoto Protocol and the Paris Agreement. Treaty law is not the whole of it, however. Customary environmental law, the law of the sea and human rights law each contribute distinct obligations. The International Court of Justice drew these bodies of law together when it delivered its Advisory Opinion on Obligations of States in respect of Climate Change on 23 July 2025. According to the Court, breaches of climate-related obligations fall under the general law of State responsibility, and a wrongful act may take the form of an omission, such as a lack of due diligence or a failure to regulate private emitters.

Two matters are examined here: whether existing international law permits States to be held responsible for climate harm, and how the Opinion reshapes the analysis of attribution, causation and reparation. The article contends that the central inquiry has moved on. Whether climate change is capable of engaging State responsibility is no longer seriously in doubt; the pressing task is to apply established rules to harm that accrues gradually from numerous sources. By connecting the primary obligations of climate law with the secondary rules of responsibility, the Opinion closes an important gap. Substantial obstacles persist all the same: proof of causation, the presence of multiple contributing States, the treatment of historical emissions, the valuation of environmental loss, and access to a forum possessing both jurisdiction and enforcement capacity.

The conclusion reached is that international law imposes no automatic or pro rata liability for global climate damage. Instead, it furnishes a coherent but fact-dependent route to responsibility, which becomes available once a State violates an obligation binding upon it. The extent to which that route is used will depend on international adjudication, climate science, State practice and the development of practical mechanisms for assessing and repairing climate injury.



Keywords

Climate Change; State Responsibility; International Environmental Law; International Court of Justice; Paris Agreement; Due Diligence; Causation; Reparation; Climate Litigation; International Law.



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References


A. Primary Sources

Treaties and International Instruments

  • International Law Commission, 'Articles on Responsibility of States for Internationally Wrongful Acts', annexed to UNGA Res 56/83 (02 December 2000) UN Doc A/RES/56/83.
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