Melike Pala
23 July 2025•Update: 23 July 2025
BRUSSELS
The UN's top court said Wednesday that climate change poses an "urgent and existential threat," and indicated that states have legal obligations under international law to prevent significant environmental harm caused by greenhouse gas emissions.
International Court of Justice (ICJ) President Judge Yuji Iwasawa, who delivered an advisory opinion, said greenhouse gas emissions are “unequivocally caused by human activities” and have far-reaching cross-border consequences, emphasizing the urgent need for collective global action.
"The consequences of climate change are severe and far-reaching. They affect both natural ecosystems and human populations. These consequences underscore the urgent and existential threat posed by climate change," he said.
The opinion, which was requested by the UN General Assembly in 2023, follows a legal initiative spearheaded by small island nations that are particularly vulnerable to rising sea levels.
Iwasawa confirmed that states are bound by obligations under international environmental and human rights law to prevent significant harm to the climate system. They include duties of due diligence, cooperation and adaptation under key climate treaties such as the UN Framework Convention on Climate Change, the Kyoto Protocol and the Paris Agreement.
He underscored that states must adopt appropriate regulatory measures to ensure the "deep, rapid and sustained" reduction of greenhouse gas emissions, emphasizing uncoordinated national efforts would not be sufficient, reinforcing the legal requirement for international cooperation.
Iwasawa recognized that the adverse effects of climate change "may significantly impair" fundamental human rights such as the right to life, health, water, food and housing, further highlighting that the right to a clean, healthy and sustainable environment is inseparable from the enjoyment of other human rights.
"In order to guarantee the effective enjoyment of human rights, states must take measures to protect the climate system and other parts of the environment. Under international human rights law, states are required to take necessary measures in this regard," he said.
He asserted that the climate crisis goes beyond a mere legal challenge, describing the issue as "an existential problem of planetary proportions that imperils all forms of life and the very health of our planet."
Iwasawa said states have a continuing duty to act, including stopping harmful conduct, ensuring non-repetition and making reparations, and that any breach of climate obligations is an internationally "wrongful act."
In such cases, the responsible state must cease the wrongful conduct, provide assurances against future violations, and offer full reparation to affected states.
While the advisory opinion is not legally binding, it is expected to shape global climate litigation and national policies for years.
