See that small "hot spot" in the U.S. Southwest near the Four Corners region? It shows an extraordinarily dense concentration of the greenhouse gas methane. At triple the standard ground-based estimate, it's the largest concentration ever seen over the United States. So what's causing it?

Methane is a particularly nasty greenhouse gas. It's very efficient at trapping heat in the atmosphere, and like carbon dioxide, it contributes to climate change. This particular spot near the Four Corners intersection of Arizona, Colorado, New Mexico, and Utah covers an area about 6,500 square kilometers (2,500 square miles), which is about half the size of Connecticut.

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From 2003 to 2009, this area released about 0.59 million metric tons of methane into the atmosphere. That's nearly 3.5 times the estimate for the same area in the European Union's Emissions Database for Global Atmospheric Research. The results were recently published in the journal Geophysical Research Letters. The researchers used observations made by the ESA's SCIAMACHY instrument, which measured greenhouse gases from 2002 to 2012. The hotspot persisted throughout the study. And in fact, the spot was so anomalous that the scientists suspected an instrument error. But it's very real.

Anomalous U.S. methane emissions (or how much the emissions differ from average background concentrations) for 2003 to 2009, as measured by the European Space Agency's SCIAMACHY instrument. 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 – the area where Arizona, Colorado, New Mexico and Utah meet — is the only red spot on the map. (Image and caption: AGU/NASA/JPL-Caltech/University of Michigan.)

A release from the American Geophysical Union explains what's behind the hot spot:

The study's lead author, Eric Kort of the University of Michigan, Ann Arbor, noted the study period predates the widespread use of hydraulic fracturing, known as fracking, near the hot spot. This indicates the methane emissions should not be attributed to fracking but instead to leaks in natural gas production and processing equipment in New Mexico's San Juan Basin, which is the most active coalbed methane production area in the country.

Natural gas is 95-98 percent methane. Methane is colorless and odorless, making leaks hard to detect without scientific instruments.

"The results are indicative that emissions from established fossil fuel harvesting techniques are greater than inventoried," Kort said. "There's been so much attention on high-volume hydraulic fracturing, but we need to consider the industry as a whole."

Coalbed methane is gas that lines pores and cracks within coal. In underground coal mines, it is a deadly hazard that causes fatal explosions almost every year as it seeps out of the rock. After the U.S. energy crisis of the 1970s, techniques were invented to extract the methane from the coal and use it for fuel. By 2012, coalbed methane supplied about 8 percent of all natural gas in the United States. [emphasis added]

So coalbed methane is to blame, along with shoddy practices.

Thankfully, something is being done about it. Back in March of this year, the Obama Administration announced a strategy to reduce methane emissions under its Climate Action Plan. The strategy includes improving the measurement and monitoring of methane emissions and assessing current methane emissions data.

[Via AGU]