I believe there is a fair amount of evidence that we are heating up. For now. 30 years ago we were cooling.
I don't believe there is ANY science that shows its CO2 causing it, when there are so many factors that affect climate, AND that the earth has heated up much faster in the past (before there were any cars about).
The thing that really gets me is the total amount of CO2 is less than .04% of the total atmosphere. That's not 4 percent, but 4/100 percent! The rest is nitrogen, oxygen, and argon. And finally, greenhouse theory states that the upper atmosphere should be heating more than at ground level. Its not.
Personally, I blame deforestation and the effect of heat islands (cities), for any human involvement. Makes much more sense. Guess where most of the temps taken over the past 100 years to measure changes have been located? Cities, which have ever more asphalt.
BTW, it is almost certainly deforestation that has eliminated most of the glacier on Kilimanjaro. There are brutally hot updrafts which rip up the mountain there, which didn't exist before they leveled the forest on it's flanks. Also, there is no significant heating in equatorial regions. Any changes are within margin of error.
Although I am an environmentalist big time, I also think its crap science to blame CO2. We should cut the pollution anyway though. Its bad by itself. I believe the Green movement will be a mega boom economically in the long run. imagine all the new industries and jobs.
We need a Kyoto protocol to stop wasting the forests.