The wave of new evidence of low climate sensitivity, the existence of which is denied by the CCC's David Kennedy and downplayed by Julia Slingo, has presented the IPCC with a dilemma. They could try to bluff it out, an approach that could be terminal given the widespread reporting of the new science in the media. Alternatively they could 'fess up. This too could be extremely damaging, but perhaps might not be the end of them.
Being good bureaucrats they have gone for the option that is most likely to lead to their survival. At least that is what I surmise from a posting at the Economist, which has managed to get its hands on a table from the IPCC's Fifth Assessment Report. According to the article, a draft of the WG3 report reveals that
at CO2 concentrations of between 425 parts per million and 485 ppm, temperatures in 2100 would be 1.3-1.7°C above their pre-industrial levels. That seems lower than the IPCC’s previous assessment, made in 2007. Then, it thought concentrations of 445-490 ppm were likely to result in a rise in temperature of 2.0-2.4°C.
Now of course, it's draft and its WG3, not WG1, so we have to be cautious. But there is at least a possibility that they are going turn down the alarm somewhat.