I am not a climatologist, but then hardly anyone else screaming about global warming is either. It seems obvious to me that warming is a net positive for humans. As the planet warms more areas become arable. The reduction in glaciation and the ice caps frees more water to the water cycle.
History teaches that the ice ages are droughty times which are hard on animal populations (including man) and the warm eras are times of great abundance. This is why I don't understand all of the current doom and gloom over potential warming. Unfortunately, it appears that the warming fear mongers are wrong and we are actually entering a cooling period.
This article in the Financial Post argues for the positive influence of CO2. I am not at all sure about the effects of carbon, but it does seem that high carbon levels follow warming, not the other way around.