If you want some insight into the nuances of the actual scientific debate on global warming at present, I suggest starting here. Prof. Pielke has some interesting things to say, such as:
Recently the SPM of IPCC’s AR4 stated that it’s now very likely that most of the warming of the last 50 years is the result of anthropogenic CO2. Are Global Circulation Models crucial to ‘prove’ that AGW is already taking place the last 50 years?
My answer is ‘no’. The primary aspect that GCM’s have claimed to be able to show skillfully is a globally averaged surface temperature trend (e.g. see). But the models do this without including all the forcings. The models are incomplete. What they have shown is that CO2 is just one important climate forcing, but the 2005 National Research Council report Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties shows there are other first order climate forcings. Another problem is that our research suggests that the actual warming, particularly the minimum near surface-air temperatures on land, have been overstated. There is a warm bias in these data. So if the models agree with the temperature trends, they do this, at least in part, for the wrong reasons.
Read the whole thing.