There seems to be two sources of "frozen" methane. The one you're referring to is on the ground of the oceans kind of trapped in ice. The other one is organic m

There seems to be two sources of "frozen" methane. The one you're referring to is on the ground of the oceans kind of trapped in ice. The other one is organic matter inside permafrost on land. When this warms bacteria become active and decompose the organic matter releasing methane. It was only a naive relation I saw between the bacteria inside the cows stomach and the one in the permafrost ;-)