However, we also have strong evidence from multiple independent lines of data that CO2 sensitivity is between 2 and 4.5 and at some compelling evidence that net feedback due to clouds is positive. (realclimate.org)
The fact of the matter is that IPCC has relied in AR4 on models, which assume a strongly positive net feedback from clouds, while subsequent physical observations show that the primary impact of clouds with warming is increased albedo and higher SW reflection resulting in an overall negative cloud feedback. (judithcurry.com)
In fact, my reading of the IPCC report says that the climate «consensus» is that net feedback in the climate system is positive and tends to add 2 more degrees of temperature for every one added from CO2. (climate-skeptic.com)