Climate Justice

For decades, the legal scaffolding that might hold nations accountable for climate inaction has been weak, vague or simply non-existent. Hopefully, that may now change following a major advisory opinion issued by the International Court of Justice (ICJ), the United Nations’ principal judicial organ. The advisory opinion strengthens the legal muscle behind the fight against climate change.

It is a milestone not merely because it defines more clearly what states must do but because it recognises the climate emergency as a legal problem instead of just a scientific or political one. The court concluded that the obligation to combat climate change is rooted not just in treaties like the Paris Agreement but also in customary international law, meaning those states that have shunned climate pacts cannot be excused anymore.

This is a welcome development. For too long, international climate diplomacy has resembled a club with few rules and even fewer consequences. By framing climate inaction as a breach of binding international obligations, the ICJ’s ruling opens the door to new avenues of enforcement and redress.

The opinion is not legally binding. But advisory opinions from the ICJ carry considerable moral and legal weight. States will now have to act not only out of moral imperative but legal duty to mitigate greenhouse gas emissions, to adapt to the impact of climate change and to provide financial and technological assistance where needed.

Critically, the ICJ recognised these duties as erga omnes - obligations owed to the international community as a whole. In other words, when one state fails to act, it harms not just its neighbours but everyone and any state may hold it to account. That significantly expands the possibilities for international legal action and sets a precedent for collective enforcement of climate obligations.

Perhaps most consequentially, the court linked climate action with the protection of human rights. It held that environmental degradation undermines the right to life, health and home. By doing so, it provided ammunition to those who argue that failing to tackle emissions is not just a policy failure, but a human rights violation. This argument may now be pursued not only in international forums, but in national courts too.

Large emitters, especially those outside binding treaties, may dismiss the opinion as overreach. But the court was careful to ground its findings in existing law by drawing from the Paris Agreement, the UN Framework Convention on Climate Change, the Kyoto Protocol and longstanding principles of international law such as the duty not to cause transboundary harm.

The ruling also arrives at a moment of growing judicial clarity. Earlier this month, the Inter-American Court of Human Rights reaffirmed that American states are obliged to act on the climate crisis. UN experts have pressed the Council of Europe to recognise the human right to a healthy environment. Together, these developments suggest that the architecture of international environmental law is rapidly evolving. As COP30 approaches, this opinion provides legal clarity and moral impetus for deeper commitments.