Obligations of States in Respect of Climate Change, Advisory Opinion

The urgency and global scale of the climate crisis have raised unprecedented challenges to international law.On July 23, 2025, the International Court of Justice (ICJ or Court) addressed these challenges for the first time in an advisory opinion that is remarkable for its scope, ambition, and unanimity.The campaign that led to the advisory opinion began in 2019, in a class on international environmental law at the University of the South Pacific.There, students from small island states already experiencing the effects of climate change found themselves frustrated by the gap between what they saw as the "beautiful commitments and obligations" in climate treaties, on the one hand, and the failure of states to take effective steps to meet those commitments and obligations, on the other. 1 In response to a suggestion by their professor, Justin Rose, that as an optional extracurricular activity they could explore ways to pressure the world to tackle the problem more effectively, twenty-seven students signed a letter to the states comprising the Pacific Island Forum, urging them to request an advisory opinion from the ICJ. 2 The students hoped that the Court would define more clearly what states should do to meet their obligations under international law; moreover, they believed that the Court should look at norms beyond climate treaties, including in particular human rights law. 3 Unlike most class projects, this one did not end when the class did.The students created a new organization, Pacific Island Students Fighting Climate Change, through which they continued to advocate for an ICJ advisory opinion. 4They were soon joined by youth from other countries, who started an organization of their own, World's Youth for Climate Justice, to pressure their governments to support the initiative. 5 Among states, Vanuatu took the lead in responding to the call for action.In September 2021, Vanuatu announced that it would seek a resolution of the General Assembly requesting an advisory opinion, and over the next eighteen months, it worked to build a 1 Brooke Jarvis, How a Group of Students in the Pacific Islands Reshaped Global Climate Law, N.Y.TIMES (Sept.12, 2025) (quoting Sulia Makasini, a student from Tonga).2 Id.Margaretha Wewerinke-Singh, at the time a lecturer at the university, also provided legal advice from the beginning of the campaign.