Who are you to say what plays a role and what doesn't? Why the tunnel vision? Why not look at the grand scope of things? There are thousands of factors that impact the worlds climate, why carbon dioxide alone? What about methane, H2O, natural sources of carbon, the level of biomass on the ground? All of these things play an important role. Without question, CO2 by all present data appears to be the most important, but what have we missed? We've missed something in just about every human endeavor in history, why is there no fear now? What are the consequences if we're wrong?
The only thing there is a consensus of opinion on is that the world is warming and we are the cause. What the specifics are, how, why, what can be done.....lots of disparity.
Science doesn't prove, it predicts:
http://www.livescience.com/environment/070716_gw_notwrong.html
One of many thousands of articles, even the scientists will agree on that one.