A new study throws doubt on a 1998 analysis that determined the plants and soils of the U.S. and southern Canada were absorbing as much carbon dioxide as the two societies emitted. For the study, which was published in the July 23 issue of the journal Science, researchers from the Woods Hole Research Center in Massachusetts examined land-use changes in the U.S. from 1700 to the present. Since 1945, forest growth, fire suppression efforts, and the abandonment of cropland have helped suck up more CO2, but these changes only offset “10 to 30 percent of U.S. fossil fuel emissions,” the study says.