U.S. Methane Study Says Emissions 50 Percent Higher Than EPA Estimates

WASHINGTON (AP) — The United States is spewing 50 percent more methane — a potent heat-trapping gas — than the federal government estimates, a new comprehensive scientific study says. Much of it is coming from just three states: Texas, Oklahoma and Kansas.

That means methane may be a bigger global warming issue than thought, scientists say. Methane is 21 times more potent at trapping heat than carbon dioxide, the most abundant global warming gas, although it doesn't stay in the air as long.

Much of that extra methane, also called natural gas, seems to be coming from livestock, including manure, belches, and flatulence, as well as leaks from refining and drilling for oil and gas, the study says. It was published Monday in the Proceedings of the National Academy of Science.

The study estimates that in 2008, the U.S. poured 49 million tons of methane into the air. That means U.S. methane emissions trapped about as much heat as all the carbon dioxide pollution coming from cars, trucks, and planes in the country in six months.