The sudden collapse of thawing soils in the Arctic might double the warming from greenhouse gases released from tundra, warn Merritt R. Turetsky and colleagues.

One scientist has tantalizing results, but others are not convinced. By John J. Berger.

Generating three centimeters of top soil takes 1,000 years, and if current rates of degradation continue all of the world's top soil could be gone within 60 years, a senior UN official said. By Chris Arsenault.

Right now, the government rents farmland to help protect soil and water. But once the land is farmed again, the benefits disappear. Environmentalists want to change that. By Dan Charles.