A NASA study released on Monday confirms that a methane “hot spot” in the Four Corners region of the American southwest is directly related to leaks from natural gas extraction, processing, and distribution.

The 2,500-square mile plume, first detected in 2003 and confirmed by NASA satellite data in October 2014, is said to be the largest concentration of atmospheric methane in the U.S. and is more than triple a standard ground-based estimate. Methane, the primary component of natural gas, is a highly-efficient greenhouse gas—84 times more powerful than carbon dioxide, and a significant contributor to global warming.

The study, published in the Proceedings of the National Academy of Sciences and funded primarily by NASA and the National Oceanic and Atmospheric Administration (NOAA), surveyed industry sources including gas processing facilities, storage tanks, pipeline leaks, and well pads, as well as a coal mine venting shaft.

It found that leaks from only 10 percent of the individual methane sources are contributing to half of the emissions, confirming the scientists’ suspicions that the mysterious hotspot was connected to the high level of fracking in the region.

There are more than 20,000 oil and gas wells operating in the San Juan Basin, where Arizona, Colorado, New Mexico, and Utah meet. The U.S. Energy Information Administration estimates that overall annual gas production in the basin is as much as 1.3 trillion cubic feet, mostly from coal bed methane and shale formations. 

“NASA’s finding that the oil and gas industry is primarily responsible for the ‘hot spot’ is not surprising,” stated the Western Environmental Law Center, a nonprofit public interest law firm. “In fact, the researchers found only one large source of methane not related to oil and gas operations: venting from the San Juan coal mine. This discovery renders attempts to point the finger at other potential emissions sources, like coal outcrops and landfills, definitively refuted.”