Methane is an important part of the anthropogenic radiative forcing Methane emissions have a direct GHG effect, and they effect atmospheric chemistry and stratospheric water vapour which have
additional impacts natural feedbacks involving methane likely to be important in future — via wetland response to temperature / rain change, atmospheric chemistry and, yes, arctic sources There are large stores of carbon in the Arctic, some stored as hydrates, some potentially convertible to CH4 by anaerobic resporation [from wikianswers:
Without oxygen.