World Court Declares Climate Change an Existential Threat - Lethal Heating Editor BDA

Key Points   ICJ warns of global legal obligations on climate Greenhouse gases deemed human-caused and urgent Small island states hailed ruling as historic Industrialised nations expected to lead Ruling may shape future litigation, treaties Paris Agreement’s 1.5°C goal reaffirmed

The United Nations' highest court has declared that nations must act to curb greenhouse gas emissions or risk violating international law.

In a sweeping advisory opinion issued this week, the International Court of Justice (ICJ) ruled that climate change constitutes an “existential threat” to humanity and underscored that nations, especially industrialised ones, have binding legal responsibilities to prevent further global warming.¹

The opinion, though non-binding, represents the most powerful legal statement yet on the global climate emergency.² 

The court’s declaration comes as climate-induced disasters, from deadly floods in China to record-setting heatwaves across Europe and North America, highlight the mounting toll of inaction.

“States have an obligation to take all necessary measures to ensure that activities within their jurisdiction do not cause harm to the climate system,” the opinion stated.¹

Landmark Case Led by Island Nations

The ruling followed a 2023 request brought by the United Nations General Assembly and championed by Vanuatu and other small island developing states (SIDS), whose very existence is threatened by rising sea levels and intensifying weather patterns.⁴

“This is a legal and moral victory,” said Ralph Regenvanu, Vanuatu’s Climate Minister. “The Court has confirmed that the world’s most vulnerable are entitled to protection, and that major polluters must act.”⁴

The ICJ concluded that greenhouse gas emissions are “unequivocally caused by human activities” and stressed that failure to mitigate emissions, adapt to climate change, or support vulnerable countries could breach international law.¹

Legal Force with Global Implications

Though advisory opinions from the ICJ are not enforceable, they are authoritative interpretations of international law and often influence global treaties, domestic court rulings, and multilateral negotiations.³ 

Experts say the ruling could galvanise legal action by climate-vulnerable nations, especially in pursuing compensation or demanding policy changes from major emitters.

“This is a legal tsunami,” said Payam Akhavan, international law professor at the University of Toronto and counsel for the Pacific Island nations. “It affirms that climate inaction has consequences under law—not just politics.”⁴

The Court’s opinion is expected to bolster similar cases in regional and national courts, including ongoing legal actions in Europe, South America, and Africa, where plaintiffs argue that climate inaction violates rights to life, health, and culture.⁵

Responsibility of Major Emitters

The ICJ made clear that responsibility for preventing climate harm falls disproportionately on nations with the greatest historical emissions. That includes the United States, China, the European Union, and other high-income economies.²

The Court cited the Paris Agreement’s goal to limit global warming to 1.5 °C, warning that every additional increment of temperature rise deepens human suffering and environmental loss.¹

“The ruling affirms what science has long made clear: rich nations must lead in decarbonising, financially supporting poorer states, and advancing loss and damage frameworks,” said María Fernanda Espinosa, former UN General Assembly President.⁴

Political Pressure Ahead of COP30

The ruling adds momentum to global pressure on governments to deliver ambitious climate action ahead of the COP30 summit in Belém, Brazil, this November. 

Many countries have yet to update their Nationally Determined Contributions (NDCs), which outline emission reduction targets under the Paris framework.³

For climate activists and vulnerable nations, the ICJ opinion is not just a call to conscience—it is a call to legal duty.²

“This judgment transforms the climate crisis from a policy preference into a matter of global justice,” said Shyla Raghav of the nonprofit Climate Justice Now. “There can be no more excuses.”²

Legal Era of Climate Accountability

The ruling comes as climate litigation surges globally. Over 2,500 lawsuits have now been filed across 60 jurisdictions, targeting fossil fuel companies, governments, and banks that fund polluting infrastructure.⁵

As world leaders prepare for the next phase of negotiations, legal scholars warn that the era of voluntary promises may be ending. The ICJ’s decision sets the stage for a new paradigm where legal accountability drives climate ambition.³

In the words of one ICJ judge, “The future of the planet cannot be left to political discretion. It is a matter of law.”¹

Footnotes

1. ICJ Advisory Opinion – Full text of the court’s climate ruling (23 July 2025)
2. Al Jazeera – UN court says climate change is an existential threat (23 July 2025)
3. Associated Press – ICJ warns of legal climate obligations (23 July 2025)
4. Reuters – Pacific nations welcome ICJ climate ruling (23 July 2025)
5. Columbia Law School Climate Case Chart – Global climate litigation tracker

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