On July 23, 2025, the International Court of Justice (ICJ) delivered a landmark Advisory Opinion that has reverberated far beyond the marble halls of The Hague. In a unanimous decision, the world’s highest court affirmed that states have a legal obligation to protect the environment from greenhouse gas emissions and that failure to do so may carry legal responsibility. For many, especially in the low-lying Pacific Island nations, this moment marked a historic victory—one born not in the corridors of government, but in the classrooms and activism of young law students determined to force climate justice onto the global agenda.
The roots of this case stretch back to 2019, when 27 law students at the University of the South Pacific (USP) in Port Vila, Vanuatu, convinced their government to champion climate justice at the international level. Their campaign, which grew into the Pacific Islands Students Fighting Climate Change (PISFCC), inspired a United Nations resolution in March 2023 that formally requested the ICJ’s opinion. By December 2024, oral arguments were underway, with thirteen Pacific Island countries and eleven regional organizations joining a chorus of 91 written and 107 oral statements. The students’ vision had become a global movement.
PISFCC leader Cynthia Houniuhi stood before the Court, representing not only her peers but also the countless islanders facing the existential threat of rising seas and intensifying storms. As Belyndar Rikimani, a student from the Solomon Islands, put it, “What’s very special about this campaign is that it didn’t start with government experts, climate experts or policy experts. It started with students. And these law students are not from Harvard or Cambridge or all those big universities, but they are students from the Pacific that have seen the first-hand effects of climate change. It started with students who have the heart to see change for our islands and for our people.” According to Global Voices, the USP lauded its students, declaring, “What began with Pacific Island law students from The University of the South Pacific has grown into a global movement demanding legal accountability for climate inaction.”
The ICJ’s opinion, while technically non-binding, was immediately celebrated as a “historic intervention and a victory for humanity.” The Court stated unequivocally that states must “prevent significant harm to the environment by acting with due diligence and to use all means at their disposal to prevent activities carried out within their jurisdiction or control from causing significant harm to the climate system and other parts of the environment, in accordance with their common but differentiated responsibilities and respective capabilities.” For Pacific Island nations, this was more than legalese—it was a clarion call for justice and a foundation for seeking reparations.
Transform Aqorau from the Solomon Islands captured the mood: “We now have the legal basis to seek reparations for climate harm. The door is open for Pacific Island states to demand compensation, justice, and meaningful climate finance—not as charity, but as legal right.” In Vanuatu, the decision fueled jubilant celebrations on Independence Day, with Minister of Climate Change Ralph Regenvanu urging, “The nations most responsible for emissions should be held accountable for any violations of legal obligations and they must also step up and lead in providing resources and support to aid those most affected. A victory in the world’s highest court is just the beginning.”
The ruling’s implications ripple well beyond the Pacific. According to CNBC, Günther Thallinger, a board member at Allianz, called it “perhaps the most significant climate development since the 2015 Paris Agreement.” The Court’s finding that fossil fuel production, licensing, and subsidies may constitute internationally wrongful acts sent a shiver through financial markets—though, in the short term, investors largely shrugged off the news, distracted by corporate earnings and political headlines.
Still, Thallinger warned, “If one takes as an investor what the International Court of Justice just said, then a revaluation of these assets needs to happen. Every prudent investor must do this now… Even if they don’t like the discussion around climate change, even if they would say they denigrate the Court of Justice completely, they must expect that, in some countries, some governments, some courts are going to follow this opinion.”
Ida Kassa Johannesen, head of commercial ESG at Saxo Bank, noted to CNBC that while the ICJ’s opinion is advisory and non-binding, it raises the litigation risk for companies in oil, gas, mining, and heavy industry. “Investors and particular large institutional investors may begin to reallocate capital away from high-risk sectors to manage exposure to climate-related legal and reputational risks,” she explained. However, the U.S. and China—by far the world’s largest carbon emitters—offered mixed responses. The Trump administration, according to Reuters, emphasized putting “America first,” while China’s Foreign Ministry called the ruling “positive” for climate cooperation but reaffirmed its developing nation status. These divergent reactions signal that global regulatory alignment remains a distant goal.
It’s not just markets and governments feeling the impact. The ICJ’s opinion recognized climate change as a human rights issue and highlighted the plight of vulnerable populations. Yet, as several legal commentators and advocacy groups have pointed out, the Court stopped short of giving children the recognition many feel they deserve. Despite the central role of young people in the climate justice movement—including school strikes and legal interventions—the opinion mentioned children only in passing, grouping them with other “vulnerable persons” and omitting any direct reference to the extensive jurisprudence on children’s rights developed by bodies such as the UN Committee on the Rights of the Child.
This omission is particularly glaring given the recent Sacchi et al. v. Argentina case, in which the Committee concluded that states have extraterritorial responsibilities for carbon pollution’s impact on children, and the Committee’s General Comment No. 26, which explicitly recognizes a child’s right to a clean, healthy, and sustainable environment. According to a detailed analysis, several countries—including Albania, Colombia, Portugal, and Tonga—had cited these legal foundations in their submissions to the ICJ, urging the Court to address children’s unique vulnerabilities and agency. Yet, the final opinion left these arguments largely on the sidelines.
Comparisons with the Inter-American Court of Human Rights, which explicitly referenced children’s rights and their agency in its own environmental advisory opinion, only highlight the missed opportunity. As the analysis laments, “Children were not merely the subjects of this movement—they were among its architects.” The ICJ’s silence on children’s rights, despite their disproportionate exposure to climate harms and visible advocacy, leaves a gap in an otherwise progressive text.
Nevertheless, the ICJ’s Advisory Opinion stands as a milestone in international law. Professor Steven Ratuva of New Zealand observed, “While advisory decisions aren’t legally binding, the ruling has effectively reshaped the global climate change landscape by giving more power to small states, especially those in the Pacific, to hold the big polluting countries politically, morally, and financially accountable. The power dynamics have shifted.”
As the dust settles, what happens next is uncertain. Will governments follow through on their obligations, or will the opinion remain a moral beacon with little practical effect? Will investors heed the warnings and shift capital, or will economic inertia prevail? And will the next stage of climate justice finally center the voices of children, who have so much at stake? Time, and the world’s resolve, will tell.