Scientists are beginning to question the ramifications of a giant Delaware-sized methane hot spot high up in the air. The “giant plume” is the largest collection of greenhouse gas in the air above the U.S. and is likely the result of natural gas leaks. It’s located over a stretch of desert in Southeast New Mexico, and NASA scientists have studied the methane cloud as a potent climate changer for the past three years. When it first appeared, scientists questioned its existence. “We couldn’t be sure that the signal was real,” NASA researcher Christian Frankenberg told the Washington Post. But NASA...