From 2002 to 2012, European satellite data consistently showed a “hotspot” of methane being emitted in the U.S. Southwest, but the amount was so large that scientists thought it was a phantom discovery and didn’t rush to explore the area.
“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 said.
The European Space Agency’s Scanning Imaging Absorption Spectrometer for Atmospheric Chartography consistently showed a bright red patch in the Four Corners region of the country, where Arizona, Colorado, New Mexico and Utah meet.
But eventually, Frankenberg and colleagues from NASA and the University of Michigan spent a year making measurements at ground level. Their findings validated satellite data from 2003-09 that showed concentrations of methane of about 1.3 million pounds of emissions per year, nearly 80 percent greater than U.S. Environmental Protection Agency (EPA) estimates.
Their results were published Oct. 9 in the journal Geophysical Research Letters.
Methane is one of several greenhouse gases present in the Earth’s atmosphere, and is less plentiful than carbon dioxide. But methane is arguably worse, since it is 80 percent more efficient than CO2 in short-term trapping of heat in the atmosphere. As an example: the amount of methane emitted in the Four Corners region is capable of trapping more heat than all the carbon dioxide produced by Sweden in a year.
The Four Corners hotspot released 590,000 tons of methane emissions into the atmosphere every year from 2003 to 2009, on average. That’s the equivalent of almost 15 million tons of carbon dioxide, or adding 3.1 million cars to the road every year.
The report says the source of the gas probably isn’t hydraulic fracturing, or fracking, because the data was gathered before the controversial practice became widespread. Rather, it says the methane probably is leaking from methane extraction from underground coal deposits.
This isn’t the first time methane emissions have been underestimated. Research published in February in the journal Science said the EPA had been reporting only 50 percent of the amount of methane in the atmosphere because it wasn’t including the gas that escapes while being shipped and sent through pipelines.
The EPA estimates that the Four Corners methane leak could annually exceed the amount of gas lost every year from gas pipelines; in 2012 that was the equivalent of 13 million metric tons of carbon dioxide.
As big as it is, the Four Corners hotspot isn’t the worst methane emitter in the country. In 2012, the EPA says, methane from farming generated enough methane to equal 201 million tons of CO2, landfills produced 117 million tons of CO2 equivalent, and methane from land use and forestry emitted 15 million tons of CO2 equivalent.
By Andy Tully of Oilprice.com
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