I currently fall into the lukewarm camp. Not totally convinced one way or the other. Here is what I think I know, but the issue is so politicized its hard to separate the signal from the noise.
We know CO2 is a greenhouse gas that can cause warming, and there is now more of it in the atmosphere, and that increase will cause some warming. Nobody really disputes that part. I think this is the 97% consensus part. But this is a little smoke and mirrors, because the CO2 forcing by itself is not significant in the long term.
The big deal is whether that little bit of warming causes major positive feedback from other systems, especially the all powerful water vapor cycles. This is the absolute most critical question. If the water vapor feedback is strongly positive, there will be lots of warming. If it is neutral, negative, or very slightly positive, the warming from CO2 alone is irrelevant. There are good arguments for and against positive feedback:
Against:
A strongly positive feedback is unstable, and the earth should have already over heated as the sun continues to increase output. (
http://en.wikipedia.org/wiki/Faint_young_Sun_paradox)
the data doesn't seem to support it (with increased warming, we are seeing drying out of the upper atmosphere via latest satellite data, rather than constant RH. this indicates negative feedback)
the warming has stopped for 10-17yrs now with dramatically increasing CO2
For:
some data shows constant RH with increasing temps
logical conclusions from physics supports positive feedback
the models support it (this is the weakest argument in support, to me)