The IPCC report is out, and it says pretty much what we knew it would say: Anthropogenic emissions of greenhouse gases are real, they have already warmed the planet, and they pose a major risk, but prompt action now could prevent catastrophic global warming in future. I highly recommend reading the report summary: it's full of very interesting information and very compelling charts, like this one:

In the New York Times, Elisabeth Rosenthal and Andy Revkin have a good summary of the summary:

If carbon dioxide concentrations reach twice their pre-industrial levels, the report said, the climate will likely warm some 3.5 to 8 degrees. But there would be more than a one in 10 chance of much greater warming, a situation many earth scientists say poses an unacceptable risk.
Many energy and environment experts see such a doubling as a foregone conclusion sometime after midcentury unless there is a prompt and sustained shift away from the 20th-century pattern of unfettered burning of coal and oil, the main sources of carbon dioxide, and an aggressive quest for expanded and improved nonpolluting energy options.

They also note that the IPCC, by its very nature, errs on the side of conservatism:

Scientists have recently reported evidence that the glaciers and ice sheets in the Arctic and Antarctic could flow seaward far more quickly than estimated in the past and have proposed risks to coasts could be much more imminent. But the I.P.C.C. is proscribed by its charter from entering into speculation and so could not include such possible instabilities in its assessment.

Meanwhile, Brad DeLong points to a story about how Exxon-Mobil-funded denialists are already trying to pay scientists to "undermine" the report – since clearly none of the thousands of scientists who worked on the IPCC report have sufficient skepticism. What annoys me is the way in which the IPCC report, which is truly the gold standard for any scientific project, is criticised as though it were the work of a small group of cranks. None of its critics really take its methodologies and results seriously, as opposed to deciding at the outset that it must be wrong – probably because if they did, then they wouldn't be nearly as critical.

Natural Disasters, Diseases and the Environment