Context

• Climate change has emerged as one of the most pressing existential threats to humanity, with impacts that transcend national borders and political divides.
• In this context, the International Court of Justice (ICJ), the principal judicial organ of the United Nations, has delivered a historic advisory opinion clarifying the legal obligations of states in combating climate change.
• While advisory opinions are not legally binding, they carry significant moral and political weight, serving as authoritative interpretations of international law.
• Precedents, such as the United Kingdom’s eventual compliance with the ICJ’s opinion on the Chagos Islands, illustrate their potential to influence state behaviour through global pressure.

Significance of ICJ’s Ruling

• Affirmation of States’ Duties to the Climate System
  • The ICJ’s opinion firmly establishes that states have enforceable legal obligations to protect the global climate system.
  • It aligns with the positions of other international judicial bodies, such as the International Tribunal for the Law of the Sea (ITLOS) and the Inter-American Commission on Human Rights (IACHR), both of which have recognised states’ responsibilities in addressing the climate crisis.
  • Crucially, the ICJ emphasised that these duties are not political preferences but binding obligations that no state can ignore.
  • One of the most notable aspects of the ruling is its comprehensive interpretation of multiple climate treaties, including the UN Framework Convention on Climate Change, the Kyoto Protocol, and the Paris Agreement, in conjunction with the best available scientific consensus.
  • The court elevated the 1.5°C threshold, long considered an aspirational goal under the Paris Agreement, to a concrete benchmark derived from subsequent scientific findings and COP decisions.
  • This effectively narrows the room for states to adopt weaker climate targets under their Nationally Determined Contributions (NDCs).
• Narrowing Discretion and Strengthening Accountability
  • The ICJ decisively rejected the view that states possess unfettered discretion in setting their NDCs.
  • While the Paris Agreement requires countries to articulate their highest possible ambition, the ruling clarifies that this phrase is not rhetorical but a standard with legal consequences.
  • States must adopt measures reasonably capable of achieving their stated goals, thereby transforming climate pledges from political statements into legal commitments.
  • This reasoning also reinforces the principle of common but differentiated responsibilities and respective capabilities (CBDR-RC), a cornerstone of climate justice.
• Beyond a Self-Contained Regime
  • The ruling also rejects the argument that climate treaties form a self-contained legal system immune from broader principles of international law.
  • Instead, the ICJ integrated climate obligations with established environmental law doctrines, including the duty of due diligence, the duty to prevent significant harm, and the duty to cooperate.
  • These obligations arise not only from climate-specific treaties but also from the Law of the Sea Convention, customary international law, and human rights instruments.
• Recognition of Intersection between Climate Change and Human Rights
  • Climate policies, the ICJ held, must respect the rights of vulnerable populations, and ensure a just transition.
  • Withdrawal from climate treaties, as in the case of the United States’ temporary exit from the Paris Agreement, does not nullify these obligations.
  • Moreover, the ICJ dismissed claims that states cannot be held individually accountable due to the difficulty of proving causation.
  • Scientific methods, it noted, can quantify each state’s contribution to global emissions, including historical responsibility.

Strategic Implications for the Global South

• This advisory opinion carries particular significance for small island developing states, whose survival is directly threatened by rising sea levels.
• It was their advocacy at the UN General Assembly that led to the request for the opinion.
• The ruling provides them, and the broader Global South, with a powerful legal and diplomatic tool to demand stronger action from major emitters.
• Beyond its symbolic victory, the opinion has the potential to reshape climate litigation worldwide.
• Cases such as the Ridhima Pandey v. Union of India matter, which challenges the adequacy of India’s climate policies, may now draw on this decision to argue that insufficient action violates both human rights and binding legal duties.
• For developing countries, the opinion strengthens the basis for insisting on equitable climate finance and technology transfer, while resisting measures that unfairly burden their economies.

Conclusion

• The ICJ’s advisory opinion represents a pivotal moment in the evolution of international climate law.
• By grounding climate obligations in binding legal principles, narrowing state discretion, and affirming the interplay between environmental protection and human rights, the court has armed vulnerable nations and climate advocates with new tools for accountability.
• While it remains to be seen how states will respond, the opinion sends an unambiguous message: climate inaction is not merely a political choice, it is a breach of legal duty.