A new study out on Monday says that the United States’ is emitting far more of the greenhouse gas methane than previously thought. The study, published by the National Academy of Sciences, estimates that in 2008 the US emitted 50 percent more methane gas into the atmosphere than was previously thought by the Environmental Protection Agency.

The new data indicates that methane could be a bigger challenge in combating global warming than scientists previously thought, according to the Associated Press. Here’s more from the AP:

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.

The new research, NBC News reports, “is based on atmospheric methane measurements taken from the top of telecommunications towers that stick more than 1,000 feet into the air as well as from airplanes.”