- Marine-climate interventions have received increased money and attention in recent years.
- While many projects and ideas may be well-intentioned, they’re generally not subject to strong governance or oversight, and they often pose risks of social and ecological harm, according to a new paper.
- The authors call for local, national and global rules that will make interventions “safe, equitable and effective.”
A growing number of oceans-based solutions to the climate crisis have been tried or devised in recent years, thanks largely to an influx of funding. These range from replanting lost mangroves, to modifying the genome of corals, to pumping nutrient-rich deep water to the surface, to engineering clouds to be more reflective.
While many of these projects and ideas may be well-intentioned, marine-climate interventions, as they’re called, are generally not subject to strong governance or oversight, a new paper says. The lack of accountability in the field creates risks of serious harm and could accelerate a “social-ecological crisis,” according to the paper, published in the journal Science on July 31.
“As a group of interdisciplinary marine and climate scientists, we all started thinking, ‘hang on, what’s going on here?’” Tiffany Morrison, a professor of geography at the University of Melbourne in Australia and lead author of the paper, told Mongabay. “This is actually problematic. The field is moving so fast.”
Morrison and co-authors write that “the pace of interventions is outstripping capacity to prevent unintended consequences because governance systems to ensure responsible transformation of marine systems are not yet in place.” They call for local, national and global rules that will make interventions “safe, equitable and effective.”
What’s a marine-climate intervention?
Marine-climate interventions are generally aimed at reducing greenhouse gases in the atmosphere or helping people or marine life adapt to the changing climate. Examples include sending carbon to the seabed or deep sea; fertilizing seawater with iron to boost populations of carbon-absorbing phytoplankton; farming seaweed; developing offshore wind farms; and relocating coral reefs, sometimes with human-assisted evolution.
Interventions can differ widely in terms of potential benefits, risks, and the state of policy and oversight dealing with them, the paper notes. If lumping them all together is clunky, it can be a way of encouraging holistic thinking and drawing attention to less-heralded efforts, experts say. For instance, the authors are among those who count moratoriums on offshore oil and gas activities as marine-climate interventions.
“A lot of the hype is around the highly technological solutions, whereas actually we already have some more social, institutional or policy solutions,” Morrison said.
The paper calls out a tendency to “solve the symptoms of climate change rather than the causes” — that is, to deal with narrow local issues rather than addressing the sources of greenhouse gas emissions. While narrow work doesn’t preclude broader action, institutional focus on it “can crowd out more impactful solutions,” the authors write.
Dan Friess, a professor of Earth and environmental science at Tulane University in the U.S., who wasn’t involved with the paper, said it could help get experts out of their silos.
“People will talk about seaweed aquaculture, or people will talk about alkalinity enhancement, or they’ll talk about coastal adaptation,” Friess said. “But we talk about them all under the same umbrella very rarely. Even though there are lots of links between all of those different types of interventions.”
Friess is an expert in “blue carbon,” which refers mainly to natural carbon sequestration in seagrasses, marshes and mangroves. He said he hasn’t always considered other marine-climate interventions relevant to his work.
“Rarely do I read a paper or do I even think about talking about offshore oil and gas moratoriums alongside blue carbon,” he added. “But now I realize after reading this, I should be. Because if you’re a decision-maker, you’re dealing with all of these at once.”
An oceans bubble?
The Science paper is the second in an ongoing series by a loosely knit global team of researchers that Morrison is part of. The first, published in the journal Nature Climate Change in April, included survey results from marine-climate intervention practitioners; their responses led the authors to warn that “interventions are currently being tested and deployed in an under-regulated pseudo-scientific bubble.” The survey showed that for many projects, there was a lack of consensus among practitioners as to exactly what type of climate benefit they were after. Such lack of clarity makes evaluation and accountability harder, the study says.
The Science paper offers not primary research but a review of the field, which is growing fast. Marine-climate interventions were spurred on by a 2019 special report by the Intergovernmental Panel on Climate Change that described rapid changes to the oceans and drew attention to ocean-based responses. Between 2019 and 2022, the flow of philanthropic money toward ocean-climate solutions more than tripled, according to a report by Our Shared Seas, a philanthropic data and analysis initiative.
“It’s a bit of a gold rush,” Morrison said. “All of the funders have switched to funding this stuff.”
Morrison said some philanthropic bodies, such as multinational consortium Ocean Resilience and Climate Alliance, support effective and responsible marine-climate interventions, but others aren’t as diligent. Funders and scientists have a “de facto governance role” due to a regulatory vacuum, and this a problem because they aren’t accountable to the general public and because a wide variety of stakeholders are often left out of decision-making, Morrison said, echoing language in the new paper.
“For interventions where few established government policies exist (such as genetically modifying corals or removing and storing carbon in deep water), scientists, investors, and nongovernmental organizations are playing a governing role by default, affording them considerable influence over experimentation and implementation, but with limited formal boundaries and accountability,” the paper says.
The authors call for rules that would require public communication about a project’s risks and require credible monitoring, reporting and verification of climate benefits.
Kristina Gjerde, a senior high seas adviser to the Global Ocean Team at the IUCN, the global nature conservation authority, praised the authors for drawing attention to governance issues and for broadening discussions of marine-climate interventions. Gjerde, who wasn’t involved with the paper, said she was “super glad” it was published in Science, a leading journal.
“The people focusing on many of these climate interventions are very narrowly focused,” Gjerde told Mongabay. “It’s ‘what can we do to change the alkalinity here? What can we do to change the production of phytoplankton here?’ … So the things that have been raised in this article are really timely and important.”
Many interventions involve potential trade-offs that require careful deliberation, Gjerde said.
“What sort of harm are you willing to accept to the marine environment to have some temporary influence on climate change?” she said in explaining how knotty the issues at hand are.
“This is exactly the type of debate that is too big for any commercial interest or even a scientific research interest,” she added.
Gjerde said some interventions, such as engineering clouds, would require human maintenance for decades to centuries — a “huge social investment” — and need to be judged against other climate solutions like rejigging transport systems.
Gjerde said the Science paper should have focused even more on international governance because the questions that marine-climate interventions raise need to be worked out at the global level so that social and ecological harm can be addressed consistently. She said, for example, that the United Nations General Assembly should adopt a resolution on marine geoengineering that enshrines the precautionary principle and establishes a system of liability for states and private actors. She warned of the potential harmful impacts posed by marine geoengineering, which are wide-ranging and laid out in a paper published in May in Environmental Research Letters; she said the Science paper should have noted these threats.
Both Gjerde and the Science paper’s authors cited the Nagoya–Kuala Lumpur Supplementary Protocol on Liability and Redress, which creates legal pathways for enforcement and redress, as an example of a model governance framework that could be applied to other interventions. The treaty deals primarily with the transboundary movement of genetically modified organisms. Dozens of countries have agreed to it as an add-on to the Convention on Biological Diversity.
How to balance speed with good process?
Ocean Visions is a U.S.-based nonprofit that supports ocean-climate startups. Its CEO, Brad Ack, told Mongabay that he agrees with the fundamental finding of the Science paper that rules are needed to ensure that interventions are safe, equitable and effective.
“The main difference, if it even exists, is that Ocean Visions would argue that the mounting risks of climate-driven disruption to oceans and planetary stability are underweighted in our risk analyses of potential interventions,” Ack told Mongabay in an email. “We do not have [a] risk-risk framework that adequately includes the enormous risks of surpassing critical tipping points in the earth system that would have unimaginable potential consequences.”
Ack called for the implementation of governance mechanisms that enable responsible interventions that will allow climate goals to remain achievable.
Weighing the importance of speedy climate action against democratic processes, which are seldom speedy, can be complicated. Neil Adger, a professor of geography at the University of Exeter in the U.K. and a co-author of the Science paper, told Mongabay in an email that “many interventions ride roughshod over other users and conservation interests” and consequently faced local opposition. (He wasn’t referring to Ocean Visions-related projects.)
Adger cited a case from southwest England in which Canada-based startup Planetary Technologies tried to set up an ocean alkalinity enhancement operation but recently abandoned the effort after running up against local resistance. Such projects involve adding alkaline substances to the sea — like giving them an antacid, as proponents sometimes say. The chemistry change allows the ocean to draw more carbon dioxide out of the atmosphere.
Planetary Technologies, whose business model involves selling carbon credits, conducted a small trial in St. Ives Bay in Cornwall in 2022, in which it added a magnesium-hydroxide slurry to treated wastewater flowing into the bay. The trial had regulatory approval, but the general public wasn’t advised or consulted until afterward, according to local advocacy and conservation groups.
“In effect the company was gaining the benefits, through selling the carbon, while any unforeseen risks were borne by the locals — a new form of extractivism,” Adger said.
A spokesperson for Planetary Technology declined to comment for this story but shared a link to the company’s explanation of the Cornwall project.
Adger emphasized the need for strong democratic input into marine-climate interventions.
“[W]e call in our paper for all proposed interventions to be subject to robust deliberation with all affected parties, giving strong weight to Indigenous and local knowledge of the seas around us,” he said.
Banner image: A green sea turtle (Chelonia mydas) swims along the Great Barrier Reef off Australia. Scientists in Australia are making efforts to bioengineer more resilient corals as part of an effort at “assisted evolution” in response to climate change. Image courtesy of Amanda Cotton/Ocean Image Bank.
Ocean-based carbon storage ramps up, bringing investment and concern
Citations:
Morrison, T. H., Pecl, G., Nash, K. L., Hughes, T., Cohen, P. J., Layton, C., … Ogier, E. (2025). Governing novel climate interventions in rapidly changing oceans. Science, 389(6759). doi:10.1126/science.adq0174
Ogier, E. M., Pecl, G. T., Hughes, T., Lawless, S., Layton, C., Nash, K. L., & Morrison, T. H. (2025). Novel marine-climate interventions hampered by low consensus and governance preparedness. Nature Climate Change, 15(4), 375-384. doi:10.1038/s41558-025-02291-4
Gallo, N. D., Metaxas, A., Lidström, S., Hetherington, E., Alfaro-Lucas, J. M., Amon, D., … Yasuhara, M. (2025). Illuminating deep-sea considerations and experimental approaches for mCDR proposals. Environmental Research Letters, 20(6), 061003. doi:10.1088/1748-9326/add8a6
Feedback: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.
Credits
This story first appeared on Mongabay
This article is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.
You may republish this article, so long as you credit the authors and Mongabay, and do not change the text. Please include a link back to the original article.
