Cathrate Guns

The Clathrate Gun is back in its holster for a moment.  The Cathrate Gun is the popular name for the theory that a warming of the oceans waters will excelerate the release of the methane gas that is trapped at the ocean bottoms, and cause a super acceleration of global warming.  Given that methane, molecule for molecule, has at least 20 times the heat-trapping properties of carbon dioxide, it’s important to get a handle on whether these are new releases, the first foretaste of some great outburst from thawing sea-bed stores of the gas, or simply a longstanding phenomenon newly observed.

Siberian shelf methane emissions not tied to modern warming
Colin Shultz, American Geophysical Union Vol 92, No 49, Pager 464, 6 December 2011 (Hat Tip: Andrew Revkin, NYT)

Eight thousand years ago, a rising sea inundated the vast permafrost regions off the northern coast of Siberia. Comprising the modern east Siberian shelf, the region holds enormous quantities of methane hydrates bottled up in remnant subterranean permafrost zones that are, in turn, trapped beneath the ocean waters.

Forecasting the expected future permafrost thaw, the authors found that even under the most extreme climatic scenario tested this thawed soil growth will not exceed 10 meters by 2100 or 50 meters by the turn of the next millennium. The authors note that the bulk of the methane stores in the east Siberian shelf are trapped roughly 200 meters below the seafloor, indicating that the recent methane emissions observations were likely not connected to the modest modern permafrost thaw. Instead, they suggest that the current methane emissions are the result of the permafrost's still adjusting to its new aquatic conditions, even after 8000 years.

So the results are somewhat positive.  Yes the gas is being released.  It’s just been going on for some time, and is not greatly effective by current warming trends.  According to Revkin’s NYT piece, there is no evidence for increased methane emissions in the last 20 years.

John Barnes in his Mother of Storms covers this scenario with the release being caused by a tactical nuclear strike in the North Pacific.