Marine geoengineering — large-scale technological intervention in ocean systems intended to alter the global climate — is increasingly entering mainstream policy discussions. Falsely framed as climate solutions, these extreme and highly speculative technologies — including ocean alkalinity enhancement, ocean fertilization, biomass sinking, and marine cloud brightening — pose profound risks to marine ecosystems and coastal communities.
This new briefing from CIEL and Friends of the Earth US, A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins, maps where these techniques may be tested or deployed and reveals that no ocean basin or coastal state is out of scope. Drawing on peer-reviewed literature and proponents’ own modeling, the brief shows that potential deployment zones span every ocean basin, with harmful impacts that could extend far beyond test sites — turning the ocean into a laboratory and threatening the livelihoods of billions of people.
At a climatically relevant scale, each marine geoengineering technology could utilize 10-20% of the ocean’s surface, and operate continuously for centuries bringing a range of impacts – including disrupting rainfall patterns, damaging delicate ecosystems, and undermining fisheries.
With experiments on the rise, and some projects already selling carbon credits, the brief highlights how carbon markets are driving certain marine geoengineering techniques in violation of international safeguards.
These extreme technologies risk undermining the vital role the ocean plays in regulating the climate system. International law is clear: precaution is not optional. Given the extraordinarily high stakes, governments must prevent the normalization of marine geoengineering and urgently prioritize effective, human rights-based solutions to the climate crisis.
This publication outlines:
- The scale and scope of potential marine geoengineering deployment
- What’s at stake for coastal communities and ecosystems
- How international law restricts deployment and commercialization
- What states must do to uphold precaution and halt open-ocean experiments
