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TWN Info Service on Climate Change (Jul25/04)
28 July 2025
Third World Network

Small Islands, Big Victory: How the Pacific Nations Just Transformed International Climate Law*

Singapore, 28 June (Goh Chien Yen) - On July 23, 2025, the International Court of Justice delivered a landmark advisory opinion that could redefine nations' obligations in fighting climate change. In its sweeping 133-page document, requested by the UN General Assembly, the court declared that existing treaties and customary law already require countries to prevent significant harm to the climate system and uphold a "clean, healthy and sustainable environment" fundamental to human rights.

The judgment follows years of diplomatic efforts led by Vanuatu and other Pacific Island States in the largest case ever heard by the ICJ. UN Secretary-General António Guterres declared the decision a victory for the planet and climate justice.

The court mandated industrialised nations to cut emissions and provide climate finance and technology to developing countries, while requiring all countries to prepare ambitious climate plans, keeping warming below 1.5°C. Crucially, the court warned that unchecked greenhouse-gas emissions, fossil-fuel expansion, or subsidies may now constitute internationally wrongful acts, triggering liability. 

Vishal Prasad, speaking on behalf of Pacific Islands Students Fighting Climate Change, the group that initiated the ICJ case, hailed the ruling as a lifeline for Pacific communities: "Today the world's smallest countries have made history. The ICJ's decision brings us closer to a world where governments can no longer turn a blind eye to their legal responsibilities. It affirms a simple truth of climate justice: those who did the least to fuel this crisis deserve protection, reparations and a future."

Why it Matters?

The ruling vindicates developing countries' long-standing arguments for clearer legal guidance and provides a foundation to demand stronger action and reparations from polluters. It confirms developed countries must lead in mitigation and support climate action through finance, technology transfers and capacity building. Significantly, it affirms that states not party to climate treaties, implicitly referencing the United States, which recently withdrew from the Paris Agreement, still owe equivalent obligations under customary law. No country can opt out of climate responsibility by leaving a treaty.

For the first time, the court explicitly affirmed the legal principle of common but differentiated responsibilities and respective capabilities (CBDR-RC) as "cardinal”, ending challenges to the simple idea that developing countries' obligations should be rightfully assessed according to their capacities and national circumstances. 

The Court made clear that violating any identified obligations constitutes an internationally wrongful act, triggering state responsibility. Wrongdoing states must cease offending conduct, provide non-repetition assurances and make full reparation, including restitution, compensation and satisfaction. Crucially, the judges emphasised that climate harms are not too diffuse to attribute; states can be held liable for cumulative emissions, and injured states may seek remedies against each responsible state.

This extends to fossil fuel exploitation and private actor behaviour. States' failure to protect the climate system from GHG emissions—including through continued fossil fuel production and consumption, granting exploration licenses or providing subsidies—may constitute internationally wrongful acts. States may also incur responsibility when failing to regulate private actors' emissions within their jurisdictions.

For developing countries, these findings unlock potential climate reparations avenues. Legal counsel Harj Narulla, representing the Solomon Islands, argues that the opinion provides a pathway for developing states to seek compensation from major emitters. "States can bring claims for compensation or restitution for all climate-related damage," he told Carbon Brief, including loss and damage.

What's Next? 

Although the decision is not legally binding, it stands as a crucial milestone and will serve as a potent leverage in upcoming climate negotiations, according to Vanuatu’s Climate Change Minister, Ralph Regenvanu. Developing nations can now invoke the court’s opinion to demand more ambitious emissions reductions, increased financial support, and robust accountability measures.

While the ICJ’s advisory opinion cannot, by itself, stop emissions or restore lost coastlines, it marks a turning point in international climate law. By weaving together treaty obligations, customary international law, and human rights principles—anchored in the cardinal concept of common but differentiated responsibilities and respective capabilities—the Court has closed legal loopholes and mapped out a path for real accountability. Pacific Island countries, once sidelined in global climate discussions, now wield a formidable legal instrument.

If rich nations heed the Court’s call, they must accelerate their emissions reductions, phase out fossil-fuel subsidies, and fulfil their commitments on climate finance. If they turn a blind eye, they risk mounting legal challenges and growing reputational costs.

For the climate-vulnerable communities that championed this case, the Court’s opinion is more than a legal milestone—it is a promise that international law can be a force for justice and for securing a safe, liveable future for all.

Sources:

·  Advisory Opinion of the International Court of Justice on the Obligations of States In Respect of Climate Change, 23 July 2025,https://www.icj-cij.org/sites/default/files/case-related/187/187-20250723-adv-01-00-en.pdf.

·  Australia warned it could face legal action over ‘wrongful’ fossil fuel actions after landmark climate ruling from world’s top court, 24 July 2025. The Guardian, https://www.theguardian.com/environment/2025/jul/24/australia-warned-it-could-face-legal-action-over-fossil-fuels-after-icj-landmark-climate-ruling.

·  Historic Climate Ruling At The International Court Of Justice, Daily Debrief,  23 July 2025. World’s Youth for Climate Justice, the Center for International Environmental Law, the Pacific Islands Students Fighting Climate Change, https://static1.squarespace.com/static/5f063a0c8f53b604aed84729/t/
6881877a1936881fe85bd8a0/1753319292895/Daily+Debrief+Reading_July+23.pdf
.

·  ICJ: What the world court’s landmark opinion means for climate change, 25 July 2025. Carbon Brief, https://www.carbonbrief.org/icj-what-the-world-courts-landmark-opinion-means-for-climate-change/.

·  State Responsibility in the ICJ’s Advisory Opinion on Climate Change, 25 July 2025. EJIL:Talk!, https://www.ejiltalk.org/state-responsibility-in-the-icjs-advisory-opinion-on-climate-change/.

·  The Die Is Cast: Some Key Implications of the ICJ Advisory Opinion on Climate Change – Cambridge International Law Journal, 25 July 205,https://cilj.co.uk/2025/07/25/the-die-is-cast-some-key-implications-of-the-icj-advisory-opinion-on-climate-change/.

·  The ICJ’s Advisory Opinion on Climate Change: An Introduction, 24 July 2025. Climate Law, A Sabin Centre Blog, https://blogs.law.columbia.edu/climatechange/2025/07/24/the-icjs-advisory-opinion-on-climate-change-an-introduction/.

·  Climate-Vulnerable States Vindicated in the Hague: A First Look at the International Court of Justice’s Climate Advisory Opinion, 25 July 2025. Just Security, https://www.justsecurity.org/117723/icj-climate-advisory-opinion/. 

* This article first was first published in Issue 15 of Oceanic Outlook: https://www.tradepac.org/debt-newsletter

 


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