Back in October, scientists discovered that the Four Corners region of the United States was a methane "hot spot," releasing large amounts of the greenhouse gas. And amidst the battle against climate change, scientists are still struggling to solve this methane mystery.

It's hard to imagine how until recently we could have missed a 2,500-square-mile cloud of methane hovering above the Four Corners region of the Southwest - where Arizona, Utah, Colorado and New Mexico meet.

Scientists actually first noticed the data years ago, but the measurements obtained were so extreme that they wanted to wait a few years before investigating the region in detail.

Last year, researchers at the University of Michigan and NASA conducted a detailed analysis using images from a European satellite taken from 2003-2009.

It turns out the data didn't lie. This methane "hot spot" is the nation's biggest concentration of methane - more than triple the standard ground-based estimate. And with methane being a more potent heat-trapping gas than even carbon dioxide (CO2), the site is a major contributor to global warming, concerning scientists everywhere.

To gain better insight into the methane concentration, NASA, along with researchers from several other institutions, are using a suite of airborne and ground-based instruments that will yield more detailed data than satellite observations.

"With all the ground-based and airborne resources that the different groups are bringing to the region, we have the unique chance to unequivocally solve the Four Corners mystery," Christian Frankenberg, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a news release.

The planes are carrying the Hyperspectral Thermal Emission Spectrometer (HyTES) and the Next-Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng), which combined can make highly sensitive measurements of methane, and show how methane levels vary even every few feet, allowing scientists to identify individual sources. (Scroll to read on...)

While most of the time people focus on CO2 as the most important greenhouse gas, methane plays just as important a role when it comes to climate change. It is the third most abundant greenhouse gas, and though there may be less of it in the atmosphere compared to CO2, it packs a much bigger punch.

Currently, more than half of atmospheric methane comes from human-related sources, such as livestock, landfills and leaks of natural gas into the atmosphere during mining, storage, transportation and distribution.

Not to mention it also comes from natural sources, such as lakes and swamps, natural-gas pipelines, deep-sea vents, and even damming beavers.

Although these sources may contribute much more to climate change than the Four Corners hot spot, it's still the largest leakage ever of the greenhouse gas - an amount equivalent to almost 15 million tons of CO2, or the equivalent of adding 3.1 million cars to the road every year, according to ThinkProgress.

Although it's still up for debate, the methane is likely not from fracking, NASA said, since the data analyzed is from 2003-2009, before the fracking boom. Instead, the scientists hypothesize that the leaks are coming from coalbed methane extraction, a process of getting natural gas from underground coal beds.

There's also the possibility 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.

Nonetheless, scientists are optimistic that their efforts will resolve the mystery and determine the quantity of methane emissions which are contributing to the climate change.

"If we can verify the methane detected by the satellite and identify its sources, decision-makers will have critical information for any actions they are considering," concluded one of the scientists, Gabrielle Pétron.

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