Could plankton really cure the world’s carbon glut?
Back in 1988, the oceanographer John Martin declared, “Give me half a tanker of iron dust, and I’ll give you an ice age.” Variants of Martin's idea about fertilizing phytoplankton with iron have spurred more than a dozen serious research initiatives. They have also drawn a cadre of true believers who reckon they can hack the ocean’s vast living carbon pump to fix the climate (or, as some claim, to grow more fish). A few early commercial exploits in iron fertilization have triggered protective reactions from international legal authorities who regard this approach as a reckless gamble with the only ocean we’ve got. So is fertilizing plankton a real climate solution? Is it an overblown dud? Or is it yet another way for people to unleash toxic algae, deplete oxygen, choke sea life, and unleash ecological havoc? Our colleagues at Ocean Visions convened a panel of experts in ocean science and policy to help craft recommendations on how philanthropies could help to sort out what’s really under the hood. I was fortunate to participate in this panel. Led by two respected consultants (Lydia Kapsenberg and Eric Schwaab), the group’s draft report is now out for public review and comment until October 30. See link below.—Brad WarrenReport Outlines Research Agenda for Potential Phytoplankton Carbon Solutions
The ocean’s smallest organisms could help fight climate change, improve ocean health
Ocean Visions | Sept 30, 2025
Ocean Visions today released a draft report outlining a prioritized research agenda for phytoplankton-based carbon dioxide removal. This potential set of climate solutions would build on the enormous productivity of ocean phytoplankton to capture and sequester additional carbon dioxide (CO₂). The draft report, developed through extensive expert consultation and literature review, identifies what is known and still unknown about this marine carbon dioxide removal (mCDR) pathway, and where the highest priority research and development is needed to close knowledge gaps and inform risk-benefit assessments. We are currently seeking feedback and response to the draft report and its recommendations until October 30, 2025.
Carbon dioxide pollution is disrupting the climate and driving ocean overheating and acidification, devastating marine life and diminishing the ocean’s ability to support life. While reducing emissions is urgent and paramount, it is no longer enough; we must also remove large amounts of the CO₂ pollution already in our atmosphere to meet climate targets (according to the Intergovernmental Panel on Climate Change (IPCC)). The ocean—covering 70 percent of the planet and already a major cycler of planetary carbon—will likely have to play a role in that removal.
Phytoplankton carbon dioxide removal involves adding nutrients to nutrient-limited parts of the ocean to stimulate growth of phytoplankton—the base of the ocean food web. Phytoplankton take up CO₂ via photosynthesis, and then lock it away when they die and sink to the deep ocean.
“Phytoplankton are among the most productive organisms on the planet, with great promise in helping clean up carbon pollution, but our understanding of many critical science questions is still insufficient. We need rigorous scientific research to close key knowledge gaps,” said Ocean Visions Senior Fellow and report co-author Eric Schwaab. “This report proposes a research road map to determine whether these potential approaches can be among the solutions needed to clean up the pollution that is currently causing so much damage to our climate and our ocean.”
The draft report maps the current landscape of phytoplankton-based carbon solutions, including ongoing science work, emerging approaches, and the scientific, technological, and socio-economic questions that remain. It identifies eight priority areas for research, proposes methods to reduce uncertainty, and recommends a phased decision-making structure. The request for public comment outlines a number of questions where we are seeking additional expert opinion.
Ocean Visions will host three public webinars on October 14, 2025 at 9:00 AM EDT, 12:00 PM EDT, and 7:00 PM EDT to accommodate diverse global participation. Input will inform the final research and development program, expected to be released in November.
“This initiative is all about building a robust and objective knowledge base to guide informed decisions by the public, stakeholders, and policymakers,” said Schwaab. “We must move ahead quickly with the research needed to determine which carbon removal pathways will meet society’s needs, and which should be discarded.”
Development of this draft report was closely guided by an international group of advisors bringing interdisciplinary scientific perspectives including oceanography, conservation, climate sciences, chemistry, and social sciences:
Mattias Cape, Marine Biogeochemical Scientist, Environmental Defense Fund
Leticia Cotrim da Cunha, Associate Professor and Coordinator of Laboratório de Oceanografia Química, Universidade do Estado do Rio de Janeiro
Anna-Maria Hubert, Assistant Professor, University of Calgary Faculty of Law
Tom Lawton, Senior Staff Scientist, John Hopkins Applied Physics Laboratory
Terre Satterfield, Professor of Culture, Risk and the Environment, The University of British Columbia
Brad Warren, Chief Executive Officer, Global Ocean Health
Angelicque White, Associate Professor, University of Hawaiʻi at Mānoa
For more information and to access the report and feedback form, visit: https://oceanvisions.org/phytoplankton-carbon-solutions/
