The Four Corners region of the southwestern U.S.– where Arizona, Utah, Colorado and New Mexico meet - is one of the most ruggedly scenic locales you could imagine.
But Four Corners has another, more puzzling distinction. As a 2014 study of data from a European satellite by NASA and University of Michigan researchers revealed, a 2,500-square mile area near the intersection produces the nation's biggest concentration of methane, a greenhouse gas that's many times more potent than carbon dioxide, and a significant contributor to global warming.
Now, as scientists launch a team effort to figure out the cause for the massive methane plume, another more troubling question arises. Is the hotspot an anomaly, or an indication that previous measurements have underestimated the amount of methane that's being released into the atmosphere?
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If the latter is true, it could have disturbing implications for the struggle against climate change.
Nobody knows yet why Four Corners is giving off so much methane - an amount equivalent to almost 15 million tons of carbon dioxide, or the equivalent of adding 3.1 million cars to the road every year, according to ThinkProgress.
For much of the 2003-2009 period in the satellite study, the area didn't have a lot of hydraulic fracturing, or fracking, for oil and gas,a process that some are concerned is a source of methane emissions. But Four Corners is a major coal mining area, and a source of coal-bed methane, which supplies about 8 percent of the nation's natural gas.
The plume discovered over Four Corners, raises the possibility that large amounts of methane are escaping from the mines - a problem that hasn't been factored into the equation before.
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There's also the possibility, as ThinkProgress notes, that we've simply been underestimating the amount of methane that human activities are releasing, and that there are other large, yet-undiscovered plumes elsewhere on the planet.
A 2014 review of study data concluded that actual U.S. methane emissions are about 61 percent higher than government estimates.
Photo: Satellite data has revealed a massive methane hotspot in the Four Corners region. Credit: NASA