An unexpectedly high amount of the climate-changing gas methane, the main component of natural gas, is escaping from the Four Corners region in the U.S. Southwest, according to a new study by the University of Michigan and NASA.

 

The researchers mapped satellite data to uncover the nation's largest methane signal seen from space. They measured levels of the gas emitted from all sources, and found more than half a teragram per year coming from the area where Arizona, New Mexico, Colorado and Utah meet. That's about as much methane as the entire coal, oil, and gas industries of the United Kingdom give off each year.

 

Four Corners sits on North America's most productive coalbed methane basin. Coalbed methane is a variety of the gas that's stuck to the surface of coal. It is dangerous to miners (not to mention canaries), but 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.

 

Kort, first author of a paper on the findings published in Geophysical Research Letters, says the controversial natural gas extraction technique of hydraulic fracturing is not the main culprit.

 

"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 map shows anomalous U.S. methane emissions (that is, how much the emissions are higher or lower than average) for 2003-2009, as measured by SCIAMACHY. Purple and dark blue areas are below average. Pale blue and green areas are close to normal or slightly elevated. Yellows and red indicate higher-than-normal anomalies, with more intense colors showing higher concentrations. The Four Corners area is the only red spot on the map.

 

 

PHOTO: The Four Corners area (red) is the major U.S. hot spot for methane emissions in this map showing how much emissions varied from average background concentrations from 2003-2009 (dark colors are lower than average; lighter colors are higher).