Some fig trees can convert surprisingly large amounts of carbon dioxide into stone, ensuring that the carbon remains in the soil long after the tree has died. This means that fig trees planted for forestry or their fruit could offer additional climate benefits through this carbon-sequestration process. All trees take up CO2 from the air, and most of that carbon typically ends up as structural molecules used to build the plant, such as cellulose. Some trees, however, convert CO2 into a crystal compound called calcium oxalate, which bacteria in the tree and the soil can then convert to calcium carbonate, the main component of stones like limestone and chalk. Carbon…