FARMINGTON - Scientists in specialized vans and planes will survey the skies over the Four Corners this month to learn more about a mysterious methane bloom.

In a packed lecture hall at San Juan College on Friday, researchers from the University of Colorado, University of Michigan, the National Oceanographic Atmospheric Administration, and NASA presented data on the local phenomenon and their plans to study it.

The recently discovered methane hot spot is the largest recorded in the U.S. and centers on the Colorado-New Mexico border in La Plata and San Juan, N.M., counties.

Methane, a natural and human-made greenhouse gas, is a contributor to global warming and smog.

The localized anomaly was revealed in a 2014 study by scientists analyzing climate data collected between 2003 and 2009 from the European SCIAMACHY satellite.

Eric Kort, a climate expert from the University of Michigan, specializes in greenhouse gases and was lead author of the study. Methane is of particular concern, he said, because, like carbon dioxide, it is a greenhouse gas, but its emissions are much more potent than carbon dioxide.

"That simply means if we increase atmospheric concentrations of methane, it is going to increase temperatures, and that has a global context as well as for local air quality concerns," Kort said.

Globally, atmospheric methane has risen in the last 200 years, going from 700 parts per billion (ppb) before the Industrial Age, to 1800 ppb today.

Methane revealed

Many suspects are fingered for the locally elevated concentration, both natural and human-caused.

Natural seepage of methane from geologic deposits in the San Juan Basin is a likely contributor; methane leaks from oil and gas wells and infrastructure are another.

A recent study of methane leaks in the U.S. showed "oil and gas sectors are important contributors, and that (methane) emissions are consistently underestimated," Kort said.

Also, the Four Corners is the No. 1 producer in the U.S. of coal-bed methane, a type of natural gas. And, according to the EPA, natural-gas emissions from the Four Corners approaches 10 percent of the nation's total.

A widely viewed satellite image showing the local methane hot spot alarmed the public, climate scientists, and environmentalists. But a lot of it was likely blown in from elsewhere and settled, officials said.

"It is a product of both emissions and wind transport," Kort said. "The signal stands out because of the isolated region, the dynamic nature of the winds, and mountains that block in the air and cause it to pool."

Other sources of methane are wetlands, landfills and cattle operations.

It was noted that large wildfires do not produce a lot of methane, but smoldering fires tend to produce more. The localized methane bloom is not concentrated enough to cause an explosive hazard.

Aircraft campaign

In the next two weeks, seven NOAA and NASA aircraft will take air samples to validate satellite data, and try to tease out methane produced locally verses methane that is blown in.

Some planes will measure overall greenhouse-gas emissions in the basin on a large grid pattern. Other planes will take point-source measurements while circling over identified spikes of methane such as well pads.

Wind direction and speed are factored into specific airborne testing areas to determine how much methane has been added because of wind transport, and the rate at which it is flowing out.

"We can see the background (methane) and the plume, and determine the total amount of methane added to the atmosphere," Kort said.

Isotope analyses can determine if the methane came from cows, landfills, or fossil fuels.

The aircraft are flying out of Durango, and two of them are from NASA's Jet Propulsion Laboratory.

"Once methane is emitted, it lives in the atmosphere for nine years and is blown all over the planet, which is why it has such high background levels," said Christian Frankenberg, a NASA scientist specializing in greenhouse gases.

Ground campaign

Two NOAA mobile methane labs will cruise public roads in La Plata and eastern Montezuma counties in the next two weeks taking measurements.

The strange-looking vehicles feature a pole that extending in front that has an attached air flask. Inside is a suite of computers and instruments.

"We will be mapping the methane plume and monitoring its persistence," said Gabrielle Petron, an atmospheric scientist with CU.

Air-quality instruments on the vans continually detect methane in real time, and will reveal spikes in concentration that will be mapped out. Montezuma County is on the fringe of the methane outcrop's western border, Petron said, and will be surveyed in the Mancos area.

The results of the ground and airborne methane studies are expected in one year.