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Scientists Discover Southwest US is a Methane 'Hot Spot'

Oct 10, 2014 05:43 PM EDT
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methane "hot spot" in southwest US
Scientists have discovered a massive methane "hot spot" in the southwest United States - a surprising development considering that the region is the largest leakage ever of the greenhouse gas, and more than triple the standard ground-based estimate.

(Photo : NASA/JPL-Caltech/University of Michigan)

Scientists have discovered a massive methane "hot spot" in the southwest United States - a surprising development considering that the region is the largest leakage ever of the greenhouse gas, and more than triple the standard ground-based estimate.

So how exactly did experts overlook a 2,500-square-mile cloud of methane hovering above the Four Corners region of the Southwest?

Scientists first noticed the data years ago amid satellite measurements collected by the European Space Agency's (ESA) Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument. From 2002 to 2012, SCIAMACHY collected atmospheric data over the United States. The bright red patch, or "hot spot," over the Four Corners persisted throughout the study period, but the readings were so extreme scientists still waited several more years before investigating the region in detail.

"We didn't focus on it because we weren't sure if it was a true signal or an instrument error," Christian Frankenberg from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Cali. said in a statement.

Well it turns out that it was no error. Using SCIAMACHY satellite data as well as ground-based measurements from 2003 to 2009, researchers found that the region where Arizona, New Mexico, Colorado, and Utah intersect had atmospheric methane concentrations equivalent to about 1.3 million pounds of emissions a year. That's roughly 80 percent higher than the Environmental Protection Agency figures, and more than triple the amount previously estimated by European scientists.

The new study, done by NASA and the University of Michigan, was released Thursday by the journal Geophysical Research Letters.

While methane isn't the most plentiful of the heat-trapping gases in the atmosphere - unlike carbon dioxide - it certainly is the best at its job. Methane is more than 80 percent potent at trapping heat in the short term compared to carbon dioxide. No doubt, scientists are worried about its increasing amounts - the newly identified hot spot is the size of Delaware - and the fact that they are clearly having trouble tracking emissions.

Methane is a colorless, odorless gas, making leaks hard to detect without scientific instruments.

Usually hydraulic fracturing, or "fracking," is blamed for massive methane emissions. The authors of the new study are careful to note that the controversial method, which is used to extract natural gas and oil from the ground, is not liable for the Southwest's methane cloud.

The fracking fever hadn't really even caught on during the time this study was conducted. Other industrial activity in the region is likely the culprit, according to researchers, coal mining specifically.

(Photo : Flickr: Simon Fraser University)

"While fracking has become a focal point in conversations about methane emissions, it certainly appears from this and other studies that in the US, fossil fuel extraction activities across the board likely emit higher than inventory estimates," Eric Kort, lead author of the study and assistant professor of atmospheric, oceanic and space sciences at the University of Michigan, said in a university news release.

Natural gas is often advertised as a more sustainable energy source than coal, given that it releases fewer pollutants when it burns. But even a recent related study shows that unfortunately, natural gas usage won't help curb carbon emissions.

Methane does take up residence in Earth's atmosphere due to both natural and human-made sources, but according to the news release, wetlands, landfills, agriculture, and even certain bacteria contribute to build-up of the heat-trapping gas.

But Four Corners residents, rest assured. The higher methane levels are not a local safety or a health issue for residents; it's only factor in global warming.

According to Kort and his colleagues, though the hot spot can be seen from space, it doesn't necessarily mean that there aren't areas elsewhere in the country where more methane is emitted if it's dispersed by wind.

"One has to be somewhat careful in equating abundances with emissions," cautioned Frankenberg. "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."

However, the region will "further spur an effort to understand methane emissions in the US," Terry Engelder, a professor of geosciences at Pennsylvania State University in State College, who was not involved in the study, told The Christian Science Monitor.

Unfortunately, SCIAMACHY is no longer operating, so researchers can't conduct similar studies in other parts of the world. For now, Kort plans to continue investigating the southwest United States, taking readings from an airplane next year to get even closer to identifying the methane leaks.

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