Published June 5, 2025
By Joie Chowdhury, Senior Attorney at the Center for International Environmental Law, Aditi Shetye, Global Strategic Litigation Lead at the World’s Youth for Climate Justice and Researcher in Public International & Environmental Law at the British Institute of International and Comparative Law; and Theresa Amor-Juergenssen, Legal Research and Capacity-Building Lead at World’s Youth for Climate Justice.
As the 2025 UN Ocean Conference (UNOC) convenes from June 9 to 13 in Nice, France, political leaders and decision makers face a pivotal moment. The ocean, our planet’s life support system, is under siege from the escalating impacts of climate change, rising sea levels, ocean acidification, and biodiversity loss. These changes are devastating marine ecosystems, and also the livelihoods and cultures of coastal and island communities worldwide. For low-lying States, sea level rise is not a distant worry, it is an existential crisis threatening their sovereignty, and the right to self-determination.
The cause is clear: fossil fuels generate greenhouse gas (GHG) emissions, driving climate change and its resultant harms. To safeguard our ocean, and in line with international legal obligations, States must commit to a fair, fast, full, and funded phaseout of fossil fuels. A fossil fuel-free future is no longer optional— it is essential for the continued health of our ocean and the stability of life on earth.
The Moral and Legal Imperative for a Fossil-Free Ocean
At the International Court of Justice (ICJ) climate advisory opinion oral hearings in The Hague last December, counsel for Vanuatu and the Melanesian Spearhead Group delivered a profound reminder of what is at stake in the climate crisis, reflections echoed in the oral arguments of many island and coastal States:
“Vanuatu is a nation of islands and island peoples. Our peoples have built vibrant cultures and traditions over millennia that are intimately intertwined with our ancestral lands and seas. Yet today, we find ourselves on the frontlines of a crisis we did not create ⎯ a crisis that threatens our very existence…Rising sea levels are projected to submerge the entire territory of certain small island States ⎯ possibly within decades. This would inhibit the sovereignty of these States and, thus, the right of affected peoples to fully enjoy their self-determined political status. It would also force the dispersal of peoples from their ancestral homelands, undermining their right to exist as integral peoples within their own territory…For the peoples of Melanesia, whose very existence as peoples is fused with their ancestral territories, this would be tantamount to collective death.”
For nations whose identities and futures are inextricably tied to the ocean, the threat of erasure due to sea level rise and other fossil-fueled climate impacts is not a distant prospect; it is an unfolding reality. In the face of what is fundamentally a fight for survival, a business-as-usual approach is not only inadequate, it is unconscionable. Yet, across global fora major polluters continue to prioritize narrow self-interest, doing their utmost to avoid and dilute their legal duties, as States face the threat of disappearing altogether. This cycle of harm and impunity must end. A fossil-free ocean is not a lofty aspiration; it is an urgent moral and legal imperative. Recent legal developments have clarified that States already have binding obligations under existing law to address climate change and protect the ocean. These obligations must now be met with the seriousness and solidarity this moment demands.
The Relevance of the Climate Advisory Opinions
The International Tribunal for the Law of the Sea (ITLOS) Climate Advisory Opinion (2024): The UNOC Political Declaration recalls the 2024 Advisory Opinion of ITLOS on the Request for an Advisory Opinion submitted by the Commission of Small Island States on Climate Change and International Law (COSIS). Advisory opinions are authoritative clarifications of law by a court. The pronouncements of ITLOS in its climate advisory opinion ground ocean health in legal duties. ITLOS has affirmed that anthropogenic GHG emissions constitute “pollution of the marine environment” and that States are obligated to take all necessary measures to prevent, reduce, and control such pollution, guided by the best available science and a stringent and objective standard of due diligence. While the opinion limits itself to clarifying State obligations to reduce greenhouse gas emissions, the science is unequivocal: without directly confronting fossil fuel production and use, such reductions will remain out of reach.
The International Court of Justice (ICJ) Climate Advisory Opinion (Expected 2025): The ICJ is poised to clarify States’ obligations under international law to address climate change and the legal consequences of failing to meet these obligations. The ICJ advisory opinion is one to watch for ocean-relevant legal findings, as several States uplifted the impacts of climate change on ocean and coastal communities in their arguments and emphasized four ocean-relevant arguments in particular, encompassing also arguments for a fossil fuel phase out:
- Legal obligations on climate change stem not only from climate-specific treaties but also from other sources of law, such as the UN Convention on the Law of the Sea, human rights treaties, and customary international law.
- The interlocking principles—territorial integrity, self-determination, and permanent sovereignty over natural resources—must continue to apply even in the face of sea level rise.
- Under their preventive obligations, including the duty of due diligence and the precautionary principle, States must take measures to protect the environment, including the ocean and the marine environment, from greenhouse gas emissions
- States, Peoples, and individuals whose rights have been violated are entitled to specific remedies for climate-related harm, such as compensation, technological support, the preservation of sovereignty despite territorial loss, protection for climate-displaced persons, and the restoration of vital ecosystems like coral reefs and mangroves.
The Inter-American Court of Human Rights (IACtHR) Advisory Opinion (Expected 2025): Building on its 2017 advisory opinion on the environment and human rights and its 2024 Case of La Oroya Population v. Peru, as well as the arguments presented to it in the course of the climate advisory opinion proceedings in 2024, the IACtHR is expected to elaborate on States’ rights-based climate obligations in relation to climate change and the environment, including the ocean and the marine environment.
To meet legal obligations and protect our ocean, States must halt oil and gas expansion and ensure a rapid and equitable fossil fuel phase out – an obligation that cannot be further delayed without putting our planet in peril and the rights of both present and future generations. The health of our ocean is critical for our global survival.
The Path Forward
As Astrid Puentes, the UN Special Rapporteur on the Right to a Healthy Environment, has emphasized in her 2025 Report on the Ocean and Human Rights, “[I]mmediate action is essential to phase out fossil fuel reliance, protect vulnerable habitats and align ocean activities with sustainable climate and biodiversity targets.”
UNOC 2025 presents an opportunity for the ocean governance community to reaffirm its commitment to ocean protection and climate justice. By embracing a fossil-free future, States can comply with their legal obligations, stand with climate-vulnerable communities, and preserve the health of our ocean for generations to come. The law is clear: States have binding obligations to prevent climate harm and protect the ocean. The science is clearer still. This is no longer a question of policy preference. It is a matter of equity, of justice, of dignity, of survival; however, what remains in question is the political will to act accordingly.
Note: This blog post is based on the joint Key Messages Briefing Note for the UN Ocean Conference, co-produced by the Center for International Environmental Law, Pacific Island Students Fighting Climate Change, and the World’s Youth for Climate Justice.