NASA scientists have confirmed that satellite data shows a methane hot spot in the southwest United States that is so big that it was ignored for years as a possible instrument error. The cloud of methane gas — a short-lived climate pollutant (SLCP) that  is around 30 times more potent as a heat-trapping gas than carbon dioxide — takes up 2,500 square miles above the Four Corners region where Arizona, Colorado, New Mexico, and Utah intersect. The methane plume is about the size of Delaware and released about 0.59 million metric tons of methane into the atmosphere annually during the seven years it was studied from 2003 to 2009.

coal mining, coalbed methane, San Juan Basin, New Mexico

The methane cloud tracks back to 2003, before the natural gas hydraulic fracturing boom in the southwest, which has been blamed for releasing large amounts of methane. In fact, so much methane is released during fracking that it has contributed to methane’s place as the second emitter of greenhouse gas emissions in the United States. Since the cloud appeared before the boom, it seems that coal mining could be the culprit instead. According to NASA, the San Juan Basin in northwest New Mexico is the most active coalbed methane production area in the country. Coalbed methane is methane found in coal seams and supplies about eight percent of total natural gas production in the United States.

Related: Hundreds of Seeping Methane Plumes Discovered Off U.S. East Coast

The University of Michigan and NASA’s Jet Propulsion Laboratory (JPL) published the results of their study in the journal Geophysical Research Letters. The researchers used observations from the European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument that measured greenhouse gases from 2002 to 2012. “The results are indicative that emissions from established fossil fuel harvesting techniques are greater than inventoried,” said the study’s lead author, Eric Kort of the University of Michigan. “There’s been so much attention on high-volume hydraulic fracturing, but we need to consider the industry as a whole.”

+ Four corners: The largest US methane anomaly viewed from space

Via CityLab

Lead image via Preservation Nation, image via NASA