Environmental Research Letters (2015 v10 044003; doi:10.1088/1748-9326/10/4/044003) / by Tyler Lark, Holly Gibbs and Meghan Salmon
[Yale Environmental 360] Biofuel crops expanded onto 7 million acres of new land in the U.S. over a recent four-year period, replacing millions of acres of grasslands, according to new research from the University of Wisconsin. Using high-resolution satellite imagery, the researchers calculated that converting grasslands to croplands for corn and soy biofuels could have emitted as much carbon dioxide as 34 coal-fired power plants operating for one year, or the equivalent of an additional 28 million cars on the road. Nearly 80 percent of cropland expansion replaced grasslands, which store large amounts of carbon in their soils. Among them were 1.6 million acres of undisturbed natural grassland, equivalent in area to the state of Delaware, according to the report published in Environmental Research Letters. The study is the first comprehensive analysis of land-use change across the U.S. between 2008 and 2012, following the passage of the federal Renewable Fuel Standard. The law says that biofuels are supposed to be grown on existing cropland, but current federal monitoring efforts capture only national-level, aggregate land-use changes.