BRIEF: EPA May Have Underestimated Methane Leaks From Oil and Gas

(Inside Science) -- Methane emissions from U.S. oil and gas operations are 63 percent higher than government estimates, according to a new study. The findings suggest the fossil fuel industry is contributing to climate change far more than previously thought -- but there may be a simple way to solve the problem.

Methane is the main component of natural gas, and pound-for-pound it is about 84 times more potent as a greenhouse gas than carbon dioxide, over a 20-year timescale. The new paper, published today in the journal Science, integrates findings from several prior studies that measured methane downwind of oil and gas facilities between 2012 and 2016.

The researchers estimate that the fossil fuel industry leaks about 13 million metric tons of methane each year, enough to fuel 10 million homes. The short-term global warming effects from that much methane are about the same as those from all natural gas burned in the country.

“The methane leaks double the climate impact [of natural gas production and use] on a 20-year basis,” said first author Ramón Alvarez, an atmospheric chemist with the Environmental Defense Fund in Austin, Texas, and one of many researchers from more than a dozen institutions involved in the study.

The U.S. Environmental Protection Agency’s lower estimates for methane emissions are calculated using a different method. Instead of measuring the overall emissions downwind of facilities, the EPA calculates how much methane should be released from each type of equipment, then multiplies by the number of pieces of such equipment. According to Alvarez, the EPA’s emissions-per-equipment values may represent best-case scenarios, largely ignoring unusual conditions and malfunctions.

The researchers attribute most of the discrepancy between their own and the EPA’s estimates to equipment malfunctions and abnormal operating conditions, since large emission rates are only measured at a small minority of sites at any given time, said Alvarez. Thus, companies may be able to drastically reduce emissions just by fixing malfunctioning equipment. And because methane breaks down in the atmosphere faster than CO2, cutting methane emissions could have a relatively rapid impact on the climate.