Krugman flags a new paper (pdf) on the subject. He summarizes:
The normal, cautious thing is to say that there’s no way to attribute any particular event, like a heat wave in the Ukraine, to global warming — and news media have basically been bullied by this argument into rarely mentioning climate change even when reporting on extreme weather. But Hansen et al make an important point: this argument is much weaker when we’re talking about really extreme events, like temperatures more than 3 standard deviations above historical norms. Such events would almost never happen if there weren’t a rising trend in global temperatures; so when they become quite common, as they have, it’s fair to call them evidence of warming.
Agreed. And look: 9 of the 10 hottest years on record have occurred since 2000. Does any sane person think this is pure coincidence?
(Photo: A weed grows out of the dry cracked bed of O.C. Fisher Lake on July 25, 2011 in San Angelo, Texas. The 5,440 acre lake which was established to provide flood control and serve as a secondary drinking water source for San Angelo and the surrounding communities is now dry following an extended drought in the region. The lake, which has a maximum depth of 58 feet, is also used for boating, fishing and swimming. The San Angelo area has seen only 2.5 inches of rain this year. The past nine months have been the driest in Texas since record keeping began in 1895, with 75% of the state classified as exceptional drought, the worst level. By Scott Olson/Getty Images.)
The Dish 