Climate: Historic ICJ Opinion On the Obligations of States

This marks a significant turning point for international law, with substantial political implications.

UN Regional Information Centre for Western Europe

In a highly anticipated advisory opinion, delivered unanimously on July 23, 2025, the International Court of Justice (ICJ) affirmed that states have an "obligation to prevent significant damage to the environment” and must "cooperate in good faith” to curb climate change.

This is a solemn—and scathing—reminder that inaction on climate change is no longer just a political failure: it may now constitute a violation of international law. UN Secretary-General António Guterres welcomed the ICJ’s "historic advisory opinion” in a video message. "It has made clear that all states have an obligation under international law to protect the global climate system.”

Climate change, Judge Iwasawa Yuji emphasized, constitutes an "urgent and existential threat,” whose "serious and far-reaching effects […] affect both natural ecosystems and human populations.”

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