“At least one nightmare scenario can be safely crossed off worst-case climate list,” Andy Revkin writes by e-mail. “Even with intense ocean warming through this millennium, thawing won’t reach the big subsea methane deposits. There were ample signs this was overblown but new work goes farther.”
He has the full story on his Dot Earth blog:
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.
If you read the Independent of Britain, you’d certainly be thinking the worst. The newspaper has led the charge in fomenting worry over the gas emissions, with portentous, and remarkably similar, stories in 2008 and this week.
If you read geophysical journals and survey scientists tracking past and future methane emissions, you get an entirely different picture. …:
[T]he authors found that roughly 1 meter of the subsurface permafrost thawed in the past 25 years, adding to the 25 meters of already thawed soil. 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… [Read the rest.]
You may recall that SuperFreakonomics included a related discussion of methane, and why you may generate more greenhouse gases by eating hamburgers than driving a car:
Because cows — as well as sheep and other cud-chewing animals called ruminants — are wicked polluters. Their exhalation and flatulence and belching and manure emit methane, which by one common measure is about twenty-five times more potent as a green house gas than the carbon dioxide released by cars (and, by the way, humans). The world’s ruminants are responsible for about 50 percent more green house gas than the entire transportation sector.*
*See “Livestock’s Long Shadow: Environmental Issues and Options,” Food and Agriculture Organization of the United Nations, Rome, 2006; and Shigeki Kobayashi, “Transport and Its Infrastructure,” chapter 5 from IPCC Third Assessment Report, September 25, 2007.