Arctic methane emissions persist in winter
Summer and winter, wet and dry, high and low, the Arctic tundra continues to emit methane.
Image: Bureau of Land Management (Delta WSR) via Wikimedia Commons
LONDON, 22 December, 2015 – The quantity of methane leaking from the frozen soil during the long Arctic winters is probably much greater than climate models estimate, scientists have found.
They say at least half of annual methane emissions occur in the cold months from September to May, and that drier, upland tundra can emit more methane than wetlands.
The multinational team, led by San Diego State University (SDSU) in the US and including colleagues from the National Oceanic and Atmospheric Administration, and the University of Sheffield and the Open University in the UK, have published their conclusion, which challenges critical assumptions in current global climate models, in the Proceedings of the National Academy of Sciences.
Methane, a potent greenhouse gas, is about 25 times more powerful per molecule than carbon dioxide over a century, but more than 84 times over 20 years. The methane in the Arctic tundra comes primarily from organic matter trapped in soil which thaws seasonally and is decomposed by microbes.
It seeps naturally from the soil over the course of the year, but climate change can warm the soil enough to release more methane from organic matter that is currently stable in the permafrost.
“Virtually all the climate models assume there’s no or very little emission of methane when the ground is frozen. That assumption is incorrect”
Scientists have for some years been accurately measuring Arctic methane emissions and incorporating the results into their climate models. But crucially, the SDSU team says, almost all of these measurements have been obtained during the Arctic’s short summer.
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