Article body copy A new 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. To avert this fate, carbon emissions need to drop—fast. But many scientists also believe tha...