Satellite Data Reveals Largest Methane Signal in the United States

Where can you find the most methane emissions in the United States? Scientists may have found that out with the use of a new map. They've mapped satellite data in order to uncover the nation's largest methane signal seen from space.

In this case, the researchers measured levels of the gas emitted from all sources. They took satellite data and then ran it through a mathematical model to account for mountains and valleys, which can trap methane. They found that more than half a teragram per year came from the area where Arizona, New Mexico, Colorado and Utah meet. These emissions constitute about as much methane as the entire coal, oil and gas industries of the United Kingdom give off each year.

The area is home to North America's most productive coalbed methane basin. Coalbed methane is a variety of the gas that's stuck to the surface of coal. While it's dangerous to miners, in recent decades it's been trapped 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," said Eric Kort, one of the researchers, in a news release. "A lot of the infrastructure is likely contributing. We see this large signal and it's persistent since 2003. 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 findings reveal the satellite measurements can be used to identify large sources of methane. This, in turn, can pinpoint areas that should be monitored in the future. In fact, the technique could be used for finding leaks.

"We've demonstrated that satellite measurements can help identify, locate and quantify anomalous methane emissions in regions that are unexpected," said Kort.

The findings are published in the journal Geophysical Research Letters.