Tuesday, March 05, 2019

Atmospheric methane has been rising for more than a decade; could accelerate global warming, climate change

Carbon dioxide is the biggest driver of climate change, but environmental scientists are increasingly worried about a second atmospheric gas: methane. Though there's a lot less of it in the air, it's much better at trapping heat; a ton "causes 32 times as much warming as one ton of CO2 over the course of a century," Julia Rosen reports  for the Los Angeles Times. However, it dissipates faster than CO2.

Methane is produced by a number of things, about half of them human-caused, like agriculture (cow burps, flatulence and waste), fossil-fuel operations and gas emissions from landfills. Atmospheric methane levels stopped increasing 20 years ago, but began rising again in 2007 and accelerated in 2014. Scientists aren't certain why, but they know the surge will likely speed up global warming, Rosen reports. It's probably a combination of many factors, some of which humans can influence; one could be that global warming is releasing more methane from wetlands and other natural features.

Daniel Jacob, an atmospheric chemist at Harvard University, said that plugging leaks from oil and gas wells needs to be a priority. Since methane is the primary ingredient in natural gas, companies have a financial incentive to stop leaks, he told Rosen.

A few of the nation's fossil-fuel operations are the biggest culprits for methane leaks, which Debra Wunch, an atmospheric physicist at the University of Toronto, says is "both scary and a good thing" possibly because it's easier to convince a few operations to change than all of them. "At the Barnett Shale in Texas, 2 percent of the facilities produce half of the field’s methane emissions. In Southern California, the Aliso Canyon leak released roughly 100,000 tons of methane in 2015 and 2016 — the equivalent of burning 1 billion gallons of gasoline," Rosen reports.

Scientific experiments indicate that ranchers could reduce livestock methane emissions by feeding them more fats or seaweed. "Capping landfills and using the methane they produce for electricity would help too," Rosen reports.

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