LONDON / WASHINGTON, DC, October 16, 2025 — A new report published today charts potential locations for high-risk marine geoengineering experiments, illustrating the alarming scale of proposed interventions. The report, ‘A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins,’ shows that proposals for open-ocean experiments are growing despite significant scientific, legal, and ethical barriers.
These highly speculative, large-scale technologies—intended to alter the global climate—include ocean alkalinity enhancement, ocean fertilization, biomass sinking, and marine cloud brightening, and are extremely risky.
The report was released ahead of the 47th Consultative Meeting of the London Convention/London Protocol, held from October 27 to 31, 2025, at the International Maritime Organization headquarters in London, which will include discussions on marine geoengineering.
Drawing on peer-reviewed literature and proponents’ own modeling, the report from the Center for International Environmental Law (CIEL) and Friends of the Earth US finds that potential deployment zones span every ocean basin, meaning nowhere is “out of scope” for these extreme technologies.
At scale, the impacts of marine geoengineering would not be confined to deployment sites; its widespread effects could be profound, unpredictable, and potentially irreversible, placing extreme strain on our stressed seas and putting the lives and livelihoods of up to three billion people who depend on the ocean at risk, according to the report.
In the immediate term, the alarming rise in outdoor experiments and proposals risks causing harmful local impacts and normalizing the development of these dangerous technologies.
The Center for International Environmental Law and Friends of the Earth US urge states to resist the dangerous distraction of marine geoengineering, halt open-ocean experiments, uphold and strengthen the existing precautionary governance regime, and focus on the real, proven solutions to the climate crisis.
Mary Church, CIEL Geoengineering Campaign Manager, said:
“The ocean is our greatest ally in the fight against climate breakdown. Already under severe pressure from heating, pollution, and overexploitation, it must not be treated as a laboratory for risky geoengineering experiments. Marine geoengineering is a dangerous distraction that risks irreversible harm and diverting scarce resources and political will away from proven, rights-based climate solutions. States must uphold precaution, halt the proliferation of open ocean experiments, and prevent the normalization of these extreme interventions.”
Benjamin Day, Senior Campaigner at Friends of the Earth US, said:
“To have a meaningful impact on the climate, marine geoengineering techniques would have to manipulate 10 percent, 20 percent, or even more of the earth’s oceans. Many of these approaches would use global ecological disruption as the very mechanism for changing the climate, or manipulate ocean chemistry on an unprecedented scale, with cascading impacts for marine ecosystems and the coastal communities who rely on them. Given the stakes, we must hit the brakes on the rush to develop and deploy marine geoengineering technologies.”
Media Contact
Niccolò Sarno, CIEL Media Relations (Geneva) + 41 22 506 80 37 or [email protected]
Notes to Editors
– Marine geoengineering deployment is effectively prohibited by a longstanding moratorium under the Convention on Biological Diversity.
– The London Convention (1972) and the London Protocol (1996), international treaties that regulate ocean pollution and dumping, prohibited Ocean Fertilization, and adopted a series of restrictive measures. They also called for the deployment of four additional techniques to be deferred.
– Voluntary carbon markets are a key driver of marine carbon dioxide removal projects, a category of marine geoengineering, and many projects are already selling carbon credits, according to the report released today, which also highlights the lack of credible Monitoring, Reporting, and Verification (MRV) in the vast, highly dynamic, and challenging ocean environment.
– Both the Convention on Biological Diversity and the London Convention/London Protocols effectively prohibit research projects selling carbon credits or driven by other commercial interests.
– An International Tribunal for the Law of the Sea Advisory Opinion highlights that marine geoengineering proposals may violate the UN Convention on the Law of the Sea (UNCLOS), the international treaty that establishes a legal framework for all marine and maritime activities.