Peter Sinclair of the Yale Climate Forum has just released an accessible video on Youtube including interviews with Dr Charles Miller (NASA's CARVE mission) and Dr Anton Vaks, author of this study about permafrost melt
Thanks RaenorShine.
In Peter Sinclair's brief interview co-author of this paper, Anton Vaks of Oxford University, explains these findings much more clearly than the press release did, which changes everything!
First, they are referring to a 1.5C temperature increase over pre-industrial times rather than the present, so as we already have 0.8C of warming there's only another 0.7C needed to reach the point he's concerned about.
And second, Anton Vaks says, "We have probably managed to put a finger on the threshold of when exactly the continuous permafrost begins to melt. This is probably the tipping point." So he seems to think that GHG release from permafrost is not a linear process with respect to temperature, but that the 1.5C is a threshold that will cause a major release to begin.
As others on the video point out, in theory at least we have control over GHG emissions from fossil fuels, but in the case of permafrost there's no way to control it and once started it would just go on by itself. There's a related article on the Yale Climate Change Forum which is worth reading:
http://www.yaleclimatemediaforum.org/2013/02/video-on-frozen-dirt-and-methane-we-cannot-go-there/Peter Sinclair says he's editing his interview with Dr Vaks and will post an extended version soon, so there's more to come on this scary subject.