The seas already act as a powerful buffer against the worst dangers of climate change, drawing down about a quarter of human-driven carbon dioxide emissions and absorbing the vast majority of global warming. Carbon dioxide dissolves naturally into seawater where the air and ocean meet. 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 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 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 within 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, Ocean Visions, the Grantham Environmental Trust and others. 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.

Antonius Gagern, the program director for ocean carbon dioxide removal at Additional Ventures, will lead 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,” “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 that the planet already pulls down carbon dioxide over very slow timescales: Rainwater dissolves basic rocks, producing calcium and other alkaline compounds that eventually flow into the oceans through rivers and streams. 

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