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Methane even escapes from freezing permafrost

The autumn freeze in the Arctic squeezes the gas out of some high-latitude wetland soils

The annual freeze of wetland soils lying atop permafrost in many high arctic regions may trigger a long-noted yet mysterious rise of atmospheric methane concentrations over such areas each fall, a new study suggests.

The bacteria-aided decomposition of organic material in high-latitude wetlands in large part depends on soil being warm. During the summer, the breakdown process generates prodigious amounts of methane.

As autumn slides toward winter, methane emissions should wane. Nevertheless, scientists have for decades detected an unexplained uptick in atmospheric methane at arctic latitudes during autumn, says Torben Christensen, a biogeochemist at Lund University in Sweden. Now, in the Dec. 4 Nature, he and his colleagues describe a phenomenon that could explain this anomaly in atmospheric chemistry.

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