Putting carbon back in soil may mitigate climate change

New York

THE last great hope of avoiding catastrophic climate change may lie in a substance so commonplace that we typically ignore it or else walk all over it: the soil beneath our feet.

The Earth possesses five major pools of carbon. Of those pools, the atmosphere is already overloaded with the stuff; the oceans are turning acidic as they become saturated with it; the forests are diminishing; and underground fossil fuel reserves are being emptied. That leaves soil as the most likely repository for immense quantities of carbon.