The summary for policy makers is here. It's long so I haven't read the whole thing. If you want a summary of the summary, there's a good article on it here in Nature News:
The report, a consensus document put together by 600 scientists and agreed by representatives of 113 countries, predicts continued warming of 0.2 °C per decade for the coming few decades.
Over the twenty-first century it predicts a range of 1.1-2.9 °C warming in a scenario with low emissions of greenhouse gases, and 2.4-6.4 °C in a high-emissions scenario. The warming is expected to be greatest over land and in the north, and the chance of heat-waves increasing in frequency is greater than 90%.
Well, that tells us a couple of things. First of all, early "leaks" which said that the upper bound for temperature had been lowered were wrong. As was pointed out by climate scientists at the time, the reporters had confused climate sensitivity (i.e. the increase in temperatures expected from a 2x CO2 scenario) with actual projected temperatures. In the case of climate sensitivity, the upper bound stayed the same but the lower bound went up. In the case of projected temperatures, the upper bound increased.
Secondly, there is a huge difference, particularly in the upper bound, between the low emissions scenario and the high emissions scenario. That means that lowering emissions may have a very large impact, contrary to what the "climate skeptics" have been saying (the argument that nothing we do will matter is kind of their last ditch "plan C" attempt at justifying inaction, after their all their previous claims have bitten the dust).
More from RealClimate and Deltoid.
