RealClimate - Climate Science: "RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists. We aim to provide a quick response to developing stories and provide the context sometimes missing in mainstream commentary. The discussion here is restricted to scientific topics and will not get involved in any political or economic implications of the science"
This looks line a nice site to get familiar with the science behind global warming. I admit that beyond the basics, I'm kinda in the dark here. The recent article The Wall Street Journal vs. The Scientific Consensus is an interesting display of how myths about global warming get propagated.