Over at Gristmill, John Tirman of MIT’s Center for International Studies notes the bogosity of one particular piece of mud the right-wing anti-science machine has been flinging: a petition supposedly signed by more than 17,000 scientists stating that there’s “no convincing scientific evidence” for human-caused global warming. Read the whole thing. (If it were what it purports to be, that fact would be reflected in the peer-reviewed scientific literature, which it is not.) But don’t hold your breath waiting for Chicago’s own Heartland Institute to apologize for its role in spreading this disinformation.

Those who harp on the supposed uncertainty of global warming rarely mention that uncertainty runs both ways, thus there’s a possibility that the mainstream view of climate scientists might be unduly optimistic. Florida State University oceanographer Jeff Chanton and colleagues at the University of Alaska Fairbanks and the Northeast Science Station in Cherskii, Russia, just published an article in the peer-reviewed journal Nature [if there’s a link I haven’t found it] reporting how one potential positive-feedback loop actually is contributing to warming. As Siberian permafrost melts into lakes, it releases methane–a greenhouse gas 20 times more potent but shorter-lived than carbon dioxide. “My fellow researchers and I estimate that an expansion of these thaw lakes between 1974 and 2000, a period of regional warming, increased methane emissions by 58 percent there,” says Chanton in an FSU press release. This methane dates from the Pleistocene. More melting leads to more methane which leads to more melting. Best story so far is at Seed.

At the other end of the earth, Antarctic ice cores dating back 800,000 years have been analyzed now (the last 150,000 years’ results apparently haven’t been published yet), according to a BBC report quoting Dr. Eric Wolff of the British Antarctic Survey. Current levels of carbon dioxide are outside the natural range seen in that time, and today’s rate of change is unprecedented: “In the core, the fastest increase seen was of the order of 30 parts per million (ppm) by volume over a period of roughly 1,000 years.  The last 30 ppm of increase has occurred in just 17 years.  We really are in the situation where we don’t have an analogue in our records.”