A drought that has been punishing the American West for the past two decades is among the worst dry spells there in 1,200 years, and it’s been made 38 percent more severe by global warming, finds Columbia climatologist Park Williams. He says that as climate change increasingly spurs extreme droughts, the region can expect even more wildfires, invasions of destructive bark beetles, and shortages of drinking water. Pictured above is Lake Mead, on the Nevada-Arizona border, where water levels have dropped more than one hundred feet since 2000.
