The Arctic Ocean seems to be emitting substantial amounts of methane, an important human-influenced greenhouse gas.

Eric Kort, now at NASA's Jet Propulsion Laboratory in Pasadena, California, and his team measured atmospheric methane levels during five flights over the Arctic carried out in 2009 and 2010. They detected high methane levels near the ocean surface that were not accompanied by high carbon monoxide levels, indicating that the methane did not arise from combustion. The researchers estimate that the methane-emission rate is similar to that seen off the coast of Siberia and attributed to melting permafrost.

Because high methane levels were observed over open water near sea ice, the authors say that Arctic Ocean methane emissions may increase as more sea ice melts.

Nature Geosci. http://dx.doi.org/10.1038/ngeo1452 (2012)