I agree with Steve, and while i recognize my opinion and insight doesn't count for much, I have been disappointed with the scientists, and now skeptical science, who seem to keep saying that the historic record doesn't show such a spike, so it's 'unlikely' there will be one.
Firstly, despite what they have said about previous analogs, I don't see them as being the same as current warming, as the rate of warming, as Steve has pointed out, makes a huge difference to the effect of any methane thawing.
I'm not seeing any previous warming like we're seeing now, including where sea levels are over the shelf, what the arctic sea ice is doing, the injection of ghg we have seen, and the rate of warming we're seeing/going to see.
Regardless of the facts about the mechanism by which the ESAS methane is supposed to thaw according to Wadhams' new disputed paper, you'll probably see this in the news today: "Climate change on pace to occur 10 times faster than any change recorded in past 65 million years, Stanford scientists say"
and climate central's piece on it:http://www.climatecentral.org/news/ecosystems-face-unprecedented-changes-in-the-next-century-16301
If you read the articles, you'll note a quote from Diffenbaugh:“The key difference is the rate of change,” said co-author Noah Diffenbaugh, a climate scientist and Senior Fellow at the Woods Institute for the Environment at Stanford University, in an interview. “The combination of rate and magnitude over the next century is unprecedented. In the context of the geological record of the last 65 million years, this (change in the 21st century) is likely to be an order of magnitude, or two or three orders, more rapid.”
As if one order of magnitude wasn't enough already.
enough to be concerned.
enough to see there's no historic analog.
And yet people are still insisting the paleo-record means there's nothing to worry about: a large methane release is "unlikely".
I don't follow their logic at all.
The mechanism Wadhams is suggesting seems to be supported by observed data, including observed sea temperatures, perhaps it might need more years to be more certain, but it certainly shouldn't be dismissed based on not having seen anything like what he's suggesting in the paleo-record.
As for the mechanism:
How many years has sea ice been retreating so far and for so long over the ESAS? probably less than 20. (http://climate.nasa.gov/key_indicators#seaIce
How many years have summer sea surface temperatures over the ESAS been above zero in summer? well it used to be mostly ice so again, probably less than 20 (http://www.esrl.noaa.gov/psd/map/images/sst/sst.month.anom.hov.io.gif
Any previous retreat of sea ice would have been more gradual, and any thawing too.
Any previous warming of summer temps would also have been more gradual, and any thawing too.
Wadhams' mechanism does indeed appear to be a new one, only possible because of the retreating sea ice. coupled with the rate of change and rate of warming, and how critical to the impact of methane release the rate of thawing is, I can't see how the mechanism is unsound or comparable to previous warmings.
That leaves me convinced that there is definitely reason to be concerned.