Methane escaping from melting permafrost is one of the identified potential (it is not certain) large and fast feedbacks. It could amplify human induced global warming a lot, and fast. Hot topic blogged about it. (Link via Stoat.) I haven’t read any articles on the subject and claim no expertise on how likely, fast or significant these events are, though anybody with even a basic understanding of physics should understand the basic issue.
Now, I bet in a very short time as the issue comes into more general knowledge, it is turned onto its head, and certain people start saying how rising greenhouse gases are caused by melting permafrost, just look at how it’s melting and emitting gas, naturally, and how this is not related not human emissions. (Similarly how the “CO2 lags warming” and “CO2 from the oceans” have been used as “evidence” against anthropogenic global warming – when they are evidence for it, since they show the role of CO2 as a feedback greenhouse gas in paleoclimate).