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News — Woods Hole, Mass. (Sept. 9, 2024) – While the urgent reduction of carbon dioxide (CO₂) and other greenhouse gas emissions is needed as the primary activity to curb climate change, there is broad agreement for the need to remove CO₂ already in the atmosphere. Given its outsized role in CO₂ storage, the ocean can’t be ignored for its potential for marine carbon dioxide removal (mCDR) to help improve our stressed climate system.

Several of the world’s leading scientific bodies, including the and , identified ocean iron fertilization (OIF) as an emerging climate solution, and over scientists signed onto a calling for expanded mCDR research. Governments around the world have invested tens of millions of dollars to advance ocean-climate solutions, signaling to the public sector, philanthropy, and academia the need to explore the role of the ocean in mitigating the effects of climate change.

Now, an article published in the journal Frontiers in Climate, “” spells out the work needed to assess the potential of OIF as a low cost, scalable, and rapidly deployable method of mCDR. According to an international experts group called “Exploring Ocean Iron Solutions” (ExOIS) that is organized around a responsible code of conduct, OIF needs to be studied to determine if it is an efficient, and environmentally and socially responsible method of mCDR.

“This is the first time in over a decade that the marine scientific community has come together to endorse a specific research plan for ocean iron,” said lead author, , Executive Director of the , and Senior Scientist in the Marine Chemistry and Geochemistry Department at the

OIF is a technique to add tiny amounts of the micronutrient, iron, to the ocean’s surface to promote the growth of marine plants, or phytoplankton. This growth removes CO₂ from the atmosphere, and as plankton die or are eaten, transfers some of that carbon as sinking particles for storage in the deep ocean. While large amounts of iron naturally enter the ocean, OIF is an effort to speed up that process.

“Given the ocean’s large capacity for carbon storage—more than 50 times larger than the atmosphere and 15-20 times larger than all land-based plants and soils—enhancing the ocean’s natural ability to store carbon should be considered,” according to , Project Manager for the ExOIS program, which is an independent program hosted at WHOI.

“Even if we could stop carbon emissions today, we would still need marine CDR because of all of the greenhouse gas CO₂ already in the atmosphere,” said Buesseler.

“Despite calls by the US National Academy of Science for research on carbon dioxide removal (CDR) – including marine CDR – there has been a significant gap in substantial open-ocean CDR research experiments in recent years, leaving the true efficacy and impacts of these methods largely uncertain,” said , Director of the Scripps Institution of Oceanography. She is not a co-author on the paper but has been involved in previous efforts to advance marine carbon dioxide removal studies. “It is essential to publish and openly discuss experiment frameworks like the one presented here. Peer review and open discussion of both the scientific and societal implications of this experiment are critical for advancing our understanding and application of CDR strategies.”

According to , CEO of Global Ocean Health, who is not a co-author on the paper, "We need a wide range of solutions if we're going to mitigate the devastating impacts of climate change in every community, and if ocean iron fertilization is going to be one such tool, it needs to be rigorously and independently studied and evaluated. The team assembled by Ken Buesseler and colleagues for this project brings the credibility, curiosity, and integrity we need to see in this field. We cannot let ocean-climate solutions become carnival acts, and that's why I am pleased serious projects like ExOIS are aiming to lead this work."

To move forward with understanding the suitability, efficacy, and impacts of OIF, the researchers focus on five key activities: field studies in the northeast Pacific Ocean; regional, global, and field study modeling; testing various forms of iron and delivery methods, which have differing advantages and disadvantages; advancing monitoring, reporting, and verification (MRV) for carbon and eMRV (which focuses on examining ecological changes); and advancing social science and governance efforts to go hand in hand with the physical science efforts.

The paper notes that field studies are needed to fill the knowledge gaps and target uncertainties as to whether OIF is sufficiently effective, scalable, and reproducible for mCDR. The authors said field experiments should be significantly larger and longer in duration as compared with previous OIF studies. Even at these larger pilot scales, no permanent changes are expected, as iron is rapidly and naturally depleted and mixed in the ocean. The amount of iron added during field experiments will be many thousands of times less than the amount of iron added naturally to the ocean, such as during volcanic eruptions. However, with an increase in scale comes the ability to better quantify CO₂ drawdown in the surface ocean, while also assessing the ecological and environmental consequences.

Modeling is needed for experimental planning, for synthesizing field trial results, and for predicting and extrapolating results to regional and global scales, which will be required to evaluate carbon impacts, climate effects, and overall changes to the ocean carbon cycle and ecosystem.

“We have learned in the past that conducting inexpensive and hence inconclusive field trials, or moving ahead without appropriate checks and oversight, will shut down progress as governments and the public pushback against the unknown risks of OIF and mCDR, while ignoring its potential,” the article states.

It is essential to involve public groups in discussions about whether OIF might be responsibly implemented. “It will be important to give particular attention to groups that have been historically excluded from decision-making on ocean spaces," Buesseler added.

“This paper lays out ideas on how to study what coastal rights holders and communities think about OIF, and to make sure that their views and priorities actually shape what further explorations of OIF should look like,” said journal article co-author , director of research at the Institute for Responsible Carbon Removal at American University, Washington, D.C.

“The new design for conducting OIF experiments will integrate all the latest observational assets and produce insights from the field data, and that will advance our modeling capability to accurately assess the impact of OIF on carbon removal and ecosystem response,” said journal article co-author professor at Xiamen University, China.

“Today, we have the opportunity and obligation to invest in the knowledge necessary to ensure that we can make scientifically and ethically sound decisions for the future of our planet. There is no path forward to solving the climate crisis that excludes the oceans for CDR, which along with emissions reduction will be necessary to reduce human suffering and environmental and ocean damage due to climate change,” the article concludes.

The authors acknowledge the contributions of all the participants at the Moss Landing Marine Laboratories (MLML) Exploring Ocean Iron Solutions workshop in May 2023. Financial support for the workshop was provided by the Astera Institute along with the Biological Oceanography Lab at MLML, and more generally from the MLML, San José State University. Support to produce this report was provided by the Astera Institute, the McConnell Family Foundation, and WHOI.

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Authors: Ken O. Buesseler¹, Daniele Bianchi², Fei Chai³, Jay T. Cullen⁴, Margaret Estapa⁵, Nicholas Hawco⁶, Seth John⁷, Dennis J. McGillicuddy Jr.¹, Paul J. Morris¹, Sara Nawaz⁸, Jun Nishioka⁹, Anh Pham², Kilaparti Ramakrishna¹, David Siegel¹⁰, Sarah R. Smith¹¹, Deborah Steinberg¹², Kendra A. Turk-Kubo¹³, Benjamin S. Twining¹⁴, Romany M. Webb¹⁵, Mark Wells⁵, Angelicque White⁶, Peng Xiu³, and Joo-Eun Yoon¹⁶

Affiliations:

¹Woods Hole Oceanographic Institution, Woods Hole, MA, USA

²University of California Los Angeles, Los Angeles, CA, USA

³Xiamen University, Xiamen, China

⁴University of Victoria, Victoria, BC, Canada

⁵University of Maine, Orono, ME, USA

⁶University of Hawai’i M膩noa, Honolulu, HI, USA

⁷University of Southern California Dornsife, Los Angeles, CA, USA

⁸American University, Washington, DC, USA

⁹Hokkaido University, Hokkaido, Japan

¹⁰University of California Santa Barbara, Santa Barbara, CA, USA

¹¹Moss Landing Marine Laboratories, Moss Landing, CA, USA

¹²Virginia Institute of Marine Science, Gloucester Point, VA, USA

¹³University of California Santa Cruz, Santa Cruz, CA, USA

¹⁴Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, USA

¹⁵Sabin Center for Climate Change Law, Columbia University, New York, NY,USA

¹⁶Center of Remote Sensing & GIS, Korea Polar Research Institute, ROK

About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit