Findings of a new study funded by NASA and the National Oceanic and Atmospheric Administration (NOAA) have revealed that most of the sources of greenhouse gas methane over the Four Corners region of the United States are natural gas production facilities.

In the new study published in the Proceedings of the National Academy of Sciences, researchers conducted an extensive airborne survey to analyze a previously identified methane emissions hot spot in the Four Corners regions of Arizona, Colorado, New Mexico and Utah.

Study author Christian Frankenberg, from NASA's Jet Propulsion Laboratory, and colleagues identified more than 250 sources of the methane hot spot, which include gas wells, pipelines, storage tanks and processing plants.

Using airborne spectrometers, which can identify certain atmospheric gases including methane, by way these gases absorb sunlight, researchers measured these individual sources and found that these sources emitted gas at rates that range between a few pounds to 11,000 pounds per hour.

They also found that only 10 percent of the individual methane sources are behind half of the emissions. Only a few were natural seeps from underground formation and there was just one vent from a coal mine.

"We identified more than 250 point sources, whose emissions followed a lognormal distribution, a heavy-tail characteristic," Frankenberg and colleagues wrote in their study.

"The top 10% of emitters explain about half of the total observed point source contribution and ∼1/4 the total basin emissions. "

Methane is the primary component of natural gas, a commonly used fuel source. It is also a very potent greenhouse gas 86 times more efficient at trapping heat than carbon dioxide. If this gas leaks into the air before it is used, it traps heat in the atmosphere, which contributes to global warming.

Methane emissions in the Four Corners regions are primarily linked to the production and transport of natural gas from coal beds. Emissions have spiked in recent decades amid boom in natural gas drilling.

Because it is colorless and odorless, the greenhouse gas is difficult to detect without using scientific instruments. The researchers said that the study provided a proof of concept for detecting airborne methane.

"If there's a desire to identify and address the largest methane emitters, our approach provides a way to do that. The method shows that you can easily fly over an area and actually see the plumes in real time," said study co-author Eric Kort, from the University of Michigan.

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