The International Court of Justice (ICJ), the United Nations' top legal body, delivered a historic advisory opinion on Wednesday declaring climate change an "urgent and existential threat," marking a watershed moment in the evolution of international environmental law. While the opinion is non-binding, legal experts say it will carry considerable political and legal weight as governments face mounting pressure to meet climate obligations.
"Greenhouse gas emissions are unequivocally caused by human activities which are not territorially limited," said Judge Yuji Iwasawa during the reading at the court's Great Hall of Justice in The Hague.
The ruling was prompted by a 2023 request from the U.N. General Assembly, driven by years of lobbying from vulnerable Pacific island nations like Vanuatu. The assembly asked the court to clarify two fundamental questions: what legal duties nations have under international law to combat climate change, and what consequences they face for failure to act.
"The stakes could not be higher. The survival of my people and so many others is on the line," said Arnold Kiel Loughman, Attorney General of Vanuatu, during the December 2023 hearings. More than 130 countries supported the case.
Although the ruling cannot compel countries to cut emissions, it may serve as a legal cornerstone for future lawsuits and climate-related litigation. "The court can affirm that climate inaction, especially by major emitters, is not merely a policy failure but a breach of international law," said Vishal Prasad, one of the law students who lobbied Vanuatu's government to bring the case forward.
Protesters and climate activists gathered outside the court, holding signs reading: "Courts have spoken. The law is clear. States must ACT NOW." Inside, the courtroom was packed with observers from across the globe.
Legal experts note the opinion can influence future legal instruments, including investment treaties, and empower activists to file domestic lawsuits. "What makes this case so important is that it addresses the past, present, and future of climate action," said Joie Chowdhury, senior attorney at the Center for International Environmental Law. "It's not just about future targets - it also tackles historical responsibility."
The opinion follows a surge in international legal action related to climate change. According to the Grantham Research Institute, nearly 3,000 cases have been filed in almost 60 countries as of June. While outcomes have been mixed, courts have increasingly affirmed climate-related duties. In 2019, the Netherlands' Supreme Court ruled the government has a legal obligation to protect citizens from climate harm. Earlier this year, the Inter-American Court of Human Rights and the European Court of Human Rights issued rulings reinforcing states' legal responsibilities in addressing environmental risks.
Yet global emissions continue to rise. The U.N.'s latest Emissions Gap Report warned that existing national policies put the planet on track for over 3°C of warming by 2100, far above the 1.5°C target outlined in the 2015 Paris Agreement. That accord, signed by over 190 nations, remains largely non-binding.
"We cannot solve the climate crisis without confronting its roots," Chowdhury said. "This opinion is applying binding international law, which countries have already committed to."
