American Southwest Contains Highest Level of Methane Gas, Study


High amounts of climate-changing gas methane have been discovered in the "Four Corners" region of southwest United States, according to a new study by the University of Michigan and NASA.

Using satellite data, the researchers found that over half a teragram of methane escapes per year from the region where Arizona, New Mexico, Colorado and Utah intersect. The amount is equivalent to entire emissions by coal, OIL, and gas industries of the United Kingdom every year.

Four Corners is located on North America's most productive coalbed methane basin. Coalbed methane is a variety of the gas stuck to the surface of coal. In recent decades, it's been tapped as a resource.          

"There's so much coalbed methane in the Four Corners area, it doesn't need to be that crazy of a leak rate to produce the emissions that we see. A lot of the infrastructure is likely contributing," said Eric Kort, assistant professor of atmospheric, oceanic and space sciences at the U-M College of Engineering and author of the paper, in a press release.

Natural gas is often deemed as more sustainable energy source than coal and oil because it discharges fewer pollutants when it burns.

Kort said that the controversial natural gas extraction technique, hydraulic fracturing, cannot be the main culprit as the highest concentration of methane gas was present even during pre-fracking periods.

"We see this large signal and it's persistent since 2003," Kort said. "That's a pre- fracking timeframe in this region. While fracking has become a focal point in conversations about methane emissions, it certainly appears from this and other studies that in the U.S., fossil fuel extraction activities across the board likely emit higher than inventory estimates."

The researchers said that Four Corners cannot be certainly the highest emitting region.

"One has to be somewhat careful in equating abundances with emissions," said study contributor Christian Frankenberg at Jet Propulsion Laboratory. "The Four Corners methane source is in a relatively isolated area with little other methane emissions, hence causing a well distinguishable hot-spot in methane abundances. Local or more diffuse emissions in other areas, such as the eastern U.S., may be convoluted with other nearby sources."

The finding is published in Geophysical Research Letters.         

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