Fracking leads to methane spike in atmosphere

From National Geographic:

Scientists have measured big increases in the amount of methane, the powerful global warming gas, entering the atmosphere over the last decade. Cows or wetlands have been fingered as possible sources, but new research points to methane emissions from fossil fuel production—mainly from shale gas operations in the United States and Canada—as the culprit.

The “massive” increase in methane emissions occurred at the same time as the use of fracking for shale gas took off in the U.S., says Robert Howarth, an ecologist at Cornell University and author of the study published Aug 14 in the journal Biogeosciences.

“We know the increase is largely due to fossil fuel production and this research suggests over half is from shale gas operations,” Howarth says in an interview.

This big methane increase matters because methane heats up the climate over 80 times more than an equivalent amount of carbon dioxide (CO2) in the first 20 years after it is released into the atmosphere, according to the Intergovernmental Panel on Climate Change. After 20 years most of the methane becomes CO2, which can last for hundreds of years.

Methane released from shale gas production has a slightly different chemical fingerprint compared to methane from cow burps (not farts as commonly believed) and wetlands. Previous studies show that shale gas generally has less carbon-13 relative to carbon-12 (denoting the weight of the carbon atom at the center of the methane molecule) than does methane from conventional natural gas and other fossil fuels such as coal, Howarth said.

The study took previous data on the chemical composition of methane in the atmosphere and applied a series of equations to parse out how much of this lighter form of methane could be attributed to shale gas. That lighter form of methane released during fracking is a substantial component of the overall methane rise since 2008.

A 2015 study led by John Worden of NASA’s Jet Propulsion Laboratory found that methane levels were unchanged for years, but increased sharply after 2006, growing by 25 million tons a year. Using satellites and other measures they concluded that fossil fuels were responsible for between 12 and 19 million tons of this additional methane and the rest was likely biological sources.

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