But scientists and startups are exploring whether these global commons can do even more to ease climate change, as a growing body of research finds that nations now need to both slash emissions and pull vast amounts of additional greenhouse gas out of the atmosphere to keep warming in check.
Ocean alkalinity enhancement (OAE) refers to various ways of adding alkaline substances, like olivine, basalt, or lime, into seawater. These basic materials bind with dissolved inorganic carbon dioxide in the water to form bicarbonates and carbonates, ions that can persist for tens of thousands of years in the ocean. As those CO2-depleted waters reach the surface, they can pull down additional carbon dioxide from the air to return to a state of equilibrium.
The ground-up materials could be added directly to ocean waters from vessels, placed along the coastline, or used in onshore devices that help trigger reactions with seawater.
Carbon to Sea is effectively an expansion of the Ocean Alkalinity Enhancement R&D Program, which Additional Ventures launched in late 2021 with the Astera Institute, the Grantham Environmental Trust, and others. Ocean Visions, a nonprofit research group working to advance ocean-based climate solutions, is also a partner, though not a funder. Early last year, the organizations began accepting applications for research grants for “at least $10 million” that could be put to use over the next five years. The program has committed $23 million to the research field so far.
Schroepfer, who will serve as a board chair of Carbon to Sea, said that he decided to support the field of ocean alkalinity enhancement because he consistently heard that it was a promising approach to carbon removal that needed to be closely studied, but “nobody was stepping up to do the actual funding of the work.”
“The way you get started is by doing,” he says. “And by moving, in particular, the science forward and making sure that the people who can answer these fundamental questions have the resources and time to answer them thoroughly.”
Antonius Gagern, previously the program director for ocean carbon dioxide removal at Additional Ventures, is leading the new organization.
“In looking at the different ways that the ocean is already using natural carbon pumps to sequester CO2 permanently, ocean alkalinity enhancement has emerged as, for us, the most promising one for a number of reasons,” Gagern says.
It’s “extremely scalable,” it’s “very permanent,” and it “doesn’t mess with” biological systems in the ways that other ocean-based approaches may, he adds.
‘A substantial climatic impact’
Other observers also consider ocean alkalinity enhancement a promising approach, in part because it’s one of the major ways the planet already pulls down carbon dioxide over very long time scales: rainwater dissolves basic rocks, producing calcium and other alkaline compounds that eventually flow into the oceans through rivers and streams.
These processes naturally sequester hundreds of millions of tons of carbon dioxide per year, by some estimates. And the planet has more than enough of the reactive materials required to bond with all the carbon dioxide humans have emitted throughout history.
There are potentially some additional benefits as well. Alkaline substances could reduce ocean acidification locally and might provide beneficial nutrients to certain marine organisms.
Andreas Oschlies, a climate modeler at the Helmholtz Centre for Ocean Research in Kiel, Germany, agrees that it’s one of the few carbon removal approaches that could “really deliver at scale and have a substantial climatic impact.”
“The minerals are not limiting and the reservoir, the ocean, is not limiting,” he says.
(Oschlies hasn’t received research grants from the Additional Ventures consortium but is a senior advisor to a project that has.)
He’s quick to stress, however, that there are significant challenges in scaling it up, and that far more research is needed to understand the most effective approaches and secondary impacts of such interventions.
Notably, some approaches would require mining, grinding, and moving around massive amounts of alkaline materials, all of which entails a lot of energy and environmental impacts.
“It’s a huge operation, of course, similar to fossil fuels or coal mining,” he says. “So these are all side effects we have to take into account.”
(Not all these concerns would necessarily be raised by other methods, however, like using electrochemistry to remove acid from seawater or processing existing waste from mines.)
There are additional challenges and uncertainties as well.
Several recent lab experiments found that these approaches didn’t work as well or easily as expected. Indeed, in some instances the addition of such substances reduced alkalinity as well as the uptake of carbon dioxide. This raises the possibility that these methods may only work in limited areas or circumstances, or could be more costly or complex to implement than hoped.
Some of the minerals contain trace heavy metals, which can collect in marine ecosystems. They could also alter the light conditions and biogeochemistry of the waters in ways that might harm or help various organisms.
Finally, the fact that carbon removal happens as a second step in the process makes it challenging to accurately monitor and measure how much CO2 the process really removes, particularly with approaches that occur in the turbulent, variable open oceans. That, in turn, could make it difficult to incentivize and monetize such efforts through carbon markets.
CarbonPlan, a San Francisco nonprofit that evaluates the scientific integrity of carbon removal projects and techniques, ranks ocean alkalinity enhancement on the low end of its “verification confidence levels,” which evaluate the degree to which long-term carbon removal and storage “can be accurately quantified” with existing tools and approaches.
“There is a lot of natural variability associated with these processes, which means it can be hard to discern a signal from the noise,” Freya Chay, program lead for carbon removal at CarbonPlan, said in an email.
“We’re still in exploration mode when it comes to OAE—there is a lot to learn about how to measure, monitor, and effectively deploy these technologies,” she added.
‘Getting the science right’
These challenges are precisely why it’s crucial to fund a coordinated research program into ocean alkalinity research, Gagern says. One of Carbon to Sea’s top priorities will include “getting the science right,” he says, by supporting studies designed to assess what approaches work most effectively and safely, and under what conditions.
He says that improving systems for monitoring, reporting, and verifying the carbon actually removed through these processes will also be a “major, major focus,” with efforts to develop, test, and refine sensors and models. Finally, Carbon to Sea will also prioritize “community building” in the nascent field, striving to draw in more researchers across disciplines and encourage collaborations through conferences, workshops, and fellowships.
One of Carbon to Sea’s initial grantees is the Ocean Alk-Align consortium, an international group of researchers studying the potential and environmental safety of ocean alkalinity enhancement.
“The award from Carbon to Sea enables us to rigorously investigate the promise of OAE for meaningful climate change mitigation and provides us with significant resources to tackle important questions through independent scientific study,” said Katja Fennel, who leads the consortium and is chair of the department of oceanography at Dalhousie University, in a prepared statement.
The program’s additional funding will likely go to a mix of research groups and startups.
A variety of companies are already exploring a handful of approaches. Project Vesta has been studying the potential for spreading fine olivine along beaches. A UCLA spinout, Equatic, is pairing alkaline materials and electricity to strip carbon dioxide from seawater and produce a clean form of hydrogen in the process. Ebb Carbon says it’s using electricity and membranes to produce an alkaline solution from the wastewater generated by desalination plants and industrial sites. The solution can then be returned to the ocean.
In addition, alkaline substances don’t necessarily have to make it to the oceans for carbon removal to occur. There’s also growing research and commercial interest in a broader category known as enhanced weathering. One startup, Lithos, is encouraging farmers to add crushed basalt rock to their fields, to increase crop yields and sequester carbon. Meanwhile, Travertine, a company spun out of the University of California, Berkeley, is developing ways of using mining waste to suck down and store away CO2.
Other funders of Carbon to Sea include the Builders Initiative, Catalyst for Impact, the Chan Zuckerberg Initiative, the Kissick Family Foundation, OceanKind, and the Thistledown Foundation.
Additional Ventures provides funding to accelerate research and development in three major areas: climate change, biomedical research, and community and democracy. Schroepfer also recently established a climate-focused venture capital investment firm, Gigascale Capital.
He says it’s crucial to kick-start ocean alkalinity research now because it can take years to build momentum behind a substantial, multifaceted scientific program and do the community engagement necessary to move the field forward.
“We should have started a long time ago, but here we are,” he says. “We’re starting now, so that if we need this as a technique—and it is promising—in the future years, we’ve laid the groundwork for it to be a possible tool for humanity.”
Update: This story was updated to clarify the role of Ocean Visions in the consortium, to note that some of the concerns raised don’t apply to all proposed methods, and to include additional comments.
