SAN JOAQUIN VALLEY (CBS SF) — A small hot spot in California’s Central Valley is likely the second largest concentration of the greenhouse gas methane seen over the United States, according to a new study of satellite data by scientists at NASA and the University of Michigan.

While NASA scientists cannot confirm whether the origin of the gas buildup is from natural deposits, industry, agriculture, or livestock, California environmental measurements provide clues.

Anyone traveling Interstate 5 through the San Joaquin Valley can smell the cattle ranches miles before seeing a single head of cattle. The Harris Ranch Coalinga feedlot is the largest ranch on the West Coast, producing about 150 million pounds of beef per year.

Add that on top of several other feedlots, landfills and manufacturing plants in the area, and it creates a 1,500 square mile hot spot that sits in Fresno and Kern Counties, making it one of the most highly concentrated methane emitting areas in the country.

In 2012, methane contributed to 8.3 percent of greenhouses gases emitted by California, according to the Calfornia Air Resources Board, but methane is greatly under-measured.

Dave Clegern of the California Air Resources Board says the agency is working to locate the sources of what is called “fugitive methane,” which is what escapes through leaks, pipe breaks and some natural sources. The area highlighted on the NASA map is an area of heavy oil and gas production, which is likely the source of much of the “fugitive gas” in Bakersfield area.

The study published Thursday in GeoPhysical Research Letters measured greenhouse gases from 2002 to 2012 using the European Space Agency’s Atmospheric Chartography instrument.

The report did not mention Harris Cattle Ranch, or any single facility as responsible for methane emissions, but plenty of research points to livestock and agriculture as sources.

For instance, another analysis of satellite data showed that during 2004, livestock in the U.S. emitted more methane into the atmosphere than the oil and gas industry.

An adult steer may be a very small source by itself, emitting only 80-120 kgs of methane, but with about 100 million cattle in the U.S., the EPA reports that livestock is one of the largest sources of methane. Like carbon dioxide, methane is very efficient at trapping heat in the atmosphere, contributing to global warming.

But the Central Valley of California’s methane emissions pales in comparison to the Four Corners intersection of Arizona, Colorado, New Mexico and Utah. The origin of that methane is thought to be mineral deposits.

Methane in the Central Valley is about 50 percent weaker and not present in all seasons and years than those observed in the Four Corners, according to the NASA and University of Michigan study.

And it’s no surprise. New Mexico is home to the San Juan Basin, which is the most active coal-bed methane production area in the country.

Eric Kort, the study’s lead author, noted the study predates the widespread use of fracking.

“There’s been so much attention on high-volume hydraulic fracturing, but we need to consider the industry as a whole,” Kort said.

This summer, the Obama Administration issued a Climate Action Plan to among other things, develop a strategy to reduce methane emissions. The plan outlines steps to cut methane emissions from landfills, coal mining, agriculture, and oil and gas systems through both voluntary actions and new laws.

The California Air Resources Board is also working to develop more state regulations to regulate oil and gas production and carbon offset for agriculture.

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