From 2009 to 2010 NASA’s has performed five flights over the Beaufort and Chukchi Seas at high and low altitudes. Methane was measured during these flights and it was found to be .5% higher than background levels. The origin of this methane seepage is unaccounted for though it is obviously coming from the ocean since the higher levels are concentrated around leads in the ice. Methane is a very potent greenhouse gas with a global warming potential 72 times greater than carbon dioxide over 25 years and 20 times more potent over 100 years.
More information is available at http://bit.ly/IbbmcK and the original source is Atmospheric observations of Arctic Ocean methane emissions up to 82° north in Nature Geosciences published online on April 22.