July 23, 2025 – In a historic advisory opinion, the International Court of Justice (ICJ), the United Nations’ highest judicial body, has declared climate change an “urgent and existential threat to humanity,” signaling a pivotal moment in international climate law. Delivered at the Peace Palace in The Hague, the ruling underscores the legal obligations of states to combat climate change and addresses the consequences of inaction, potentially reshaping global climate action and accountability.
The non-binding opinion, spanning over 500 pages, was prompted by a 2023 request from the UN General Assembly, led by the Pacific island nation of Vanuatu and supported by over 130 countries. The court was tasked with answering two critical questions: what are states’ obligations under international law to protect the climate system from greenhouse gas emissions, and what are the legal consequences for countries causing significant harm to the climate and environment?
ICJ President Yuji Iwasawa, delivering the opinion, emphasized that “greenhouse gas emissions are unequivocally caused by human activities” with cross-border effects, impacting both natural ecosystems and human populations. He stated, “Failure of a state to take appropriate action to protect the climate system may constitute an internationally wrongful act.” The court further recognized a “clean, healthy, and sustainable environment” as a human right, paving the way for future legal actions, including domestic lawsuits and international litigation.
The ruling marks a significant victory for small island and low-lying states, which face existential threats from rising sea levels and extreme weather. Vanuatu, a key advocate for the case, has long highlighted the disproportionate impact of climate change on vulnerable nations. “The stakes could not be higher. The survival of my people and so many others is on the line,” said Arnold Kiel Loughman, Vanuatu’s Attorney General, during hearings in December 2024.
The ICJ’s opinion also addresses historical responsibility, noting that wealthy industrialized nations, historically the largest emitters, must take the lead in curbing emissions. The court suggested that countries harmed by climate change could be entitled to reparations, though specifics would be determined on a case-by-case basis. This aspect of the ruling could open the door to future litigation against major polluters, a prospect that has alarmed nations like the United States and Russia, which opposed mandating emissions reductions.
Environmental groups and climate activists hailed the ruling as a turning point. Joie Chowdhury, a senior attorney at the Center for International Environmental Law, called it “one of the most consequential legal rulings of our times” for its focus on climate justice. Outside the Peace Palace, demonstrators waved banners reading, “Courts have spoken. The law is clear. States must act now,” chanting demands for immediate climate action.
The advisory opinion builds on recent global legal precedents. Earlier this month, the Inter-American Court of Human Rights ruled that countries have to avoid environmental harm and restore ecosystems. In 2024, the European Court of Human Rights mandated better protection against climate impacts, while in 2019, the Netherlands’ Supreme Court recognized protection from climate change as a human right. These decisions reflect a growing trend of using legal frameworks to enforce climate accountability.
While non-binding, the ICJ’s opinion carries significant legal and political weight. Experts suggest it will influence future climate litigation, diplomatic negotiations, and multilateral processes like the Paris Agreement. “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, a Fijian law student who lobbied for the case.
Critics, including major emitters, argue that existing treaties like the 2015 Paris Agreement should guide climate responsibilities, as these are largely non-binding. However, developing nations and small island states pushed for stronger, legally binding measures and financial aid from high-emission countries to address climate impacts. The ICJ’s ruling aligns with their call for greater accountability, emphasizing that states must adhere to “stringent obligations” under international law.
The ruling comes amid growing urgency, as global temperatures continue to rise, threatening ecosystems and livelihoods. Pacific Island students and activists, who were instrumental in bringing the case, expressed hope that the decision would spur action. “Climate change will become catastrophic if we do not course-correct,” said Vishal Prasad, highlighting the dire future facing small island nations.
As the world awaits the full implications of the ICJ’s opinion, the ruling sends a clear message: climate inaction is not just a policy choice but a potential violation of international law. With the courtroom packed and global attention focused on The Hague, the decision marks a critical step toward climate justice, urging states to act swiftly to secure a sustainable future for present and future generations.
Janefar Alam is a climate tech specialist based in Dhaka.
