Elevated carbon dioxide concentrations can increase carbon storage in the soil, according to results from a 12-year carbon dioxide-enrichment experiment at Oak Ridge National Laboratory. The increased storage of carbon in soil could help to slow down rising atmospheric carbon dioxide concentrations. The Department of Energy-sponsored free-air carbon dioxide-enrichment, or FACE, experiment officially ended in 2009. The conclusion and final harvest of the ORNL FACE experiment provided researchers with the unique opportunity to cut down entire trees and to dig in the soil to quantify the effects of elevated carbon dioxide concentrations on plant and soil carbon.