In a historic move with significant implications, the International Court of Justice (ICJ) has issued an advisory opinion stating that countries can be held legally responsible for the harm caused by their greenhouse gas emissions. This landmark decision opens the door for climate-vulnerable nations to seek compensation for the growing impacts of climate change, including deadly heatwaves, rising sea levels, crop failures, and infrastructure damage.
The 140-page opinion, released last Wednesday, marks a turning point in international climate law. The ICJ confirmed that all states — regardless of whether they are party to the 2015 Paris Agreement — have a “duty to prevent” harm to the global climate system. This obligation is based not only on climate treaties but also on customary international law, the UN Charter, and widely ratified environmental agreements such as the Convention on Biological Diversity and the UN Framework Convention on Climate Change (UNFCCC).
Along with the duty of prevention, the court emphasized a “duty to cooperate” in the global effort to combat climate change. This means countries must collaborate to reduce emissions, share climate data, and support one another in both mitigation and adaptation — principles already established in international agreements, but now with potential legal significance.
Perhaps the most significant development is the ICJ’s statement that failing to prevent harmful emissions is an “internationally wrongful act.” If a country’s emissions are shown to have a “causal nexus”—a direct link—to climate-related harm in another country, the responsible nation could face legal repercussions, including compensation payments.
This sets a new legal stage for developing nations and small island states, many of which have long claimed that their suffering is largely caused by pollution from wealthy, industrialized countries. Until now, these claims were mostly moral or political. With this ICJ opinion, legal cases may soon be brought in international courts and arbitration panels.
Notably, the ICJ also clarified that this duty exists regardless of participation in the Paris Agreement. That means countries like the United States, which temporarily withdrew from the Paris Agreement under the Trump administration, still have international obligations. No major emitter can claim immunity based on not participating in a single treaty.
While advisory opinions from the ICJ are not legally binding, they hold significant influence. They can lay the groundwork for future binding decisions, national court rulings, and UN-supported negotiations. Already, climate litigation is gaining momentum worldwide, with courts in Germany, the Netherlands, and Colombia recognizing legal responsibilities to protect citizens — and future generations — from climate harm.
The ICJ opinion could strengthen efforts to activate the Loss and Damage Fund, a new mechanism under the UNFCCC framework created to provide financial aid to countries facing irreversible climate impacts. It might also speed up demands for a global climate reparations framework, one that considers historical responsibility and cumulative emissions over time.
As the climate crisis worsens, the ICJ’s opinion could become a crucial component of the evolving legal framework for climate justice, shifting the focus from voluntary promises to legal obligations and from commitments to concrete actions.
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