It appears that there is no danger from methane in the arctic.

[N]ew research led by Princeton University researchers and published inThe ISME Journal in August suggests that, thanks to methane-hungry bacteria, the majority of Arctic soil might actually be able to absorb methane from the atmosphere rather than release it. Furthermore, that ability seems to become greater as temperatures rise.

http://bishophill.squarespace.com/blog/2015/8/18/defusing-the-methane-bomb.html