If the world does not reduce its greenhouse gas emissions, the U.S. Southwest is almost guaranteed to suffer decades-long megadroughts by the end of this century, says Mashable, citing work by a group of U.S. researchers. The paper, which builds on earlier findings that climate change would increase the chance of long-lasting droughts, is the first to put a number on the risk.
Lead author Toby Ault, an assistant professor at Cornell University, told Mashable, “Megadroughts are virtually certain in a business-as-usual greenhouse gas emissions scenario.” Ault said the higher temperatures expected to result from greenhouse gas emissions boost the chances of a megadrought by 70 to 99 percent by 2100, based on scenarios in which temperatures rise by 2, 4, or 6 degrees C.
The risk of megadrought is not affected by potential changes in precipitation, including higher annual rainfall. “That’s because the rising air temperatures would drive higher evaporation rates on the ground; the warmer the soil, the less likely it is to lock in moisture,” says Mashable.