The United Nations’ International Court of Justice issued a unanimous, 15-judge advisory opinion stating that countries have a legal obligation under international law to confront climate change, which it called an “urgent and existential threat.” Requested by the UN General Assembly after lobbying by Vanuatu and other low-lying states, the opinion says nations must cooperate to achieve emission cuts consistent with keeping global warming below 1.5 °C and must ensure their national climate plans reflect the “highest ambition.” Judge Yuji Iwasawa, delivering the two-hour ruling in The Hague, warned that failure to meet these “stringent obligations” constitutes an internationally wrongful act. The court said states could be held liable for the climate-related harm they cause, potentially facing “full reparations”—including compensation—if a direct causal link is proven. Governments were also told they are responsible for emissions from companies under their jurisdiction, and that the right to a clean, healthy and sustainable environment is integral to the enjoyment of other human rights. Although non-binding, the opinion carries significant legal and political weight and is expected to influence a surge of climate litigation worldwide, building on nearly 3,000 cases already filed in roughly 60 countries. Small island nations and advocacy groups hailed the decision as a milestone for climate justice, while major emitters said they would review the findings. The ruling follows a separate early-July advisory opinion from the Inter-American Court of Human Rights that similarly framed climate protection as a legal duty, underscoring a global trend toward tighter judicial scrutiny of national climate policies.