When plants are burned or decay, carbon is released, combining with oxygen to become CO 2 . But when the same plants are heated in a kiln without oxygen, a process called pyrolysis, about half of that carbon turns into charcoal, a substance so inert it takes hundreds of years to revert to CO 2 .

Pyrolysis can be performed on an industrial level—a Wisconsin-based company called best Energies sells a device that processes about two tons of wood or other biomass (including turkey waste) an hour—or on a small scale anywhere on earth. The resulting “agrichar” or “biochar” makes a great soil amendment, which means fewer greenhouse-

enhancing fertilizers, and more crops that can be turned into more biochar…It’s the most virtuous of circles.