📚 Fossil-Fuel Production May Be Responsible For Much More Atmospheric Methane Than Scientists Thought

Fossil-fuel production may be responsible for much more atmospheric methane than scientists previously thought, according to new research published today in the journal Nature. The results, if they hold, suggest that methane needs to be managed even more tightly than was accounted for in multilateral initiatives such as the 2015 Paris Agreement -- not to mention many policies on the national and local level. Bloomberg reports: Scientists aren't challenging the top-line amount of fossil methane that enters the atmosphere every year -- that number stays at about 194 million metric tons, says Benjamin Hmiel, a post-doctoral fellow in Earth science at the University of Rochester and the study's lead author. Rather, they're challenging how much of the total comes from natural versus industrial sources, an important distinction for policy-makers. Conventional wisdom has held until now that fossil sources emit roughly 50 million tons of methane. The new paper's estimate is dramatically smaller: Just 5 million tons, at most, come from natural sources, or "seeps," the study says. "If it's not coming from seeps, then it's coming from fossil-fuel operations," says Rob Jackson, a Stanford professor of Earth system science who wasn't involved in the study. "There's really no other explanation for it. It's kind of a zero-sum game." The Nature study takes advantage of a rare, radioactive form of the carbon atom that decays over several thousand years. Carbon-14 is present in trace amounts in the biosphere, embedded in naturally occurring molecules such as methane and carbon dioxide, but fossil fuels have no carbon-14 in them. Hmiel and his colleagues visited Greenland three times over two years to drill samples out of ice sheets dating back 300 years, then analyzed the gases trapped in it looking for carbon-14. This allowed scientists to establish a pre-industrial level for natural methane emissions.

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