From Smithsonian Magazine

Anew method for combatting climate change feels like a bit of modern-day alchemy: scientists have figured out how to take carbon dioxide out of the ocean and turn it into harmless rock.

For every tonne of carbon dioxide we pump into the air, roughly a quarter of it gets absorbed by the ocean like a giant, watery sponge. All of this excess carbon dioxide is acidifying the water and threatening organisms, such as those with calcium carbonate shells, that are sensitive to the change.

“You’re talking about removing some 10 to 20 gigatonnes of [carbon dioxide] per year, starting from 2050, probably for the next century,” says Gaurav Sant, a civil and environmental engineering professor and director of the Institute for Carbon Management at the University of California, Los Angeles.

To date, most efforts to capture carbon have focused on direct air capture—trying to pull the gas out of the atmosphere. But to make carbon capture more efficient, Sant’s research team is turning to the ocean for help.

Oceans and other large bodies of water can hold more than 150 times more carbon dioxide than the air. Sant and his colleagues’ idea is that if you can remove carbon from the ocean, the water will absorb more from the atmosphere to maintain a state of equilibrium. Now, they’re proposing an innovative way of getting carbon out of the ocean—by turning it into rock.