A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins

The report analyzes marine geoengineering, dividing it into marine carbon dioxide removal (mCDR) and marine solar radiation modification (SRM). It argues that these speculative technologies pose irreversible risks to ocean ecosystems and human rights, while facing significant monitoring and verification challenges. The authors contend that proposed deployment zones span every ocean basin, making the impacts inherently transboundary and potentially violating international law, including the CBD moratorium and UNCLOS.

• Proposed deployment zones for these technologies span every ocean basin, meaning no country is exempt from potential physical, ecological, and social consequences that would extend across borders.
• The report identifies severe limitations in monitoring, reporting, and verification (MRV) for mCDR, arguing that the inability to accurately account for CO2 uptake undermines the fundamental premise of these technologies.
• Ocean Alkalinity Enhancement (OAE) at a climatically relevant scale (one gigaton of CO2) would require mining operations comparable to the current global iron ore industry, potentially causing significant health and community impacts in mineral-rich regions like North Africa, the Middle East, South Asia, and Central America.
• Ocean Fertilization (OF) is projected to be attempted in high-nutrient low-chlorophyll (HNLC) regions, but may rob nutrients from downstream regions, leading to declines in marine biomass and fish communities in the Atlantic, Pacific, and Indian Oceans.
• Biomass sinking, including the use of crop residues or seaweed, risks smothering seafloor life and causing chemical changes such as reductions in oxygen and increases in hydrogen sulfide, methane, and nitrous oxide.
• Marine Cloud Brightening (MCB) carries the risk of 'termination shock,' where a sudden cessation of the technique would lead to an abrupt rise in temperatures.
• Surface albedo enhancement techniques targeting the Arctic, such as scattering hollow glass microspheres, have been found by some researchers to potentially accelerate sea ice melt and pose ecotoxicological risks to the food chain.
• The report argues that marine geoengineering is a 'dangerous distraction' that diverts resources and political will away from the necessary fast and funded phaseout of fossil fuels.
• Current global governance, including the Convention on Biological Diversity (CBD) moratorium and the London Convention/London Protocol (LC/LP), restricts marine geoengineering to small-scale scientific research, yet there is a growing number of open-ocean experiments often linked to commercial carbon credit markets.

APA

Carlson, A. M., Church, M., & Day, B. (2025). A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins. Center for International Environmental Law. https://www.ciel.org/wp-content/uploads/2025/10/A_Gathering_Storm-_How_Marine_Geoengineering_Threatens_All_Ocean_Basins_report.pdf

Chicago

Carlson, Alana M., Mary Church, and Benjamin Day. A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins. Center for International Environmental Law, 2025. https://www.ciel.org/wp-content/uploads/2025/10/A_Gathering_Storm-_How_Marine_Geoengineering_Threatens_All_Ocean_Basins_report.pdf.

Wikipedia

{{cite report |last1=Carlson |first1=Alana M. |last2=Church |first2=Mary |last3=Day |first3=Benjamin |title=A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins |publisher=Center for International Environmental Law |date=2025 |url=https://www.ciel.org/wp-content/uploads/2025/10/A_Gathering_Storm-_How_Marine_Geoengineering_Threatens_All_Ocean_Basins_report.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{carlson2025gathering, author = {Carlson, Alana M. and Church, Mary and Day, Benjamin}, title = {{A Gathering Storm: How Marine Geoengineering Threatens All Ocean Basins}}, institution = {Center for International Environmental Law}, year = {2025}, url = {https://www.ciel.org/wp-content/uploads/2025/10/A_Gathering_Storm-_How_Marine_Geoengineering_Threatens_All_Ocean_Basins_report.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }