Methane Emissions Higher Than Estimated In Los Angeles Basin

LOS ANGELES (AP) — A sensor atop a Los Angeles County mountain has found that methane emissions in the area are up to 61 percent higher than government estimates, researchers said.

While the research was not specifically designed to find out where the greenhouse gas was coming from, the largest concentrations of methane were found at ground sites in Pasadena and across eastern LA County, according to a study published this week in the journal Atmospheric Chemistry and Physics.

"This is a tremendous result from a scientific experiment," said Charles Miller, a scientist at NASA's Jet Propulsion Laboratory and co-author of the study. "For the first time, we have the capability of making maps, or images, of the distribution of methane across the LA basin."

The methane sensor, operated by the Jet Propulsion Laboratory and installed at about 5,700 feet on Mount Wilson, measured emissions from September 2011 to October 2013.

Scientists used a spectrometer, an instrument that can detect pollutants in the air based on the way the molecules move through sunlight. They pointed the device at more than two dozen Southern California sites — including Angel Stadium in Anaheim, the Rose Bowl in Pasadena and the Santa Anita Park racetrack in Arcadia — taking measurements every 90 minutes.

Scientists estimated that more than 430,000 tons of methane were released each year across the region, more than would be expected by adding up emissions from all sources inventoried by the California Air Resources Board. That number is between 18 to 61 percent higher than widely used ground estimates, according to the study.

California air quality regulators participated in the study with scientists at JPL, the California Institute of Technology and the University of Michigan.

On Wednesday, the Obama administration laid out a blueprint for the first national regulations to cut down on methane emissions from new natural gas wells, aiming to curb the discharge of the potent greenhouse gas by roughly half. The White House set a new target for the U.S. to cut methane emissions by 40 percent to 45 percent by 2025, compared to 2012 levels.

Although just a sliver of U.S. greenhouse gas emissions, methane is far more powerful than carbon dioxide at trapping heat in the atmosphere.

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