This is a pretty big question. One that many seem to think is "answered." All the scientists agree, anyone who disagrees is in the pockets of the oil companies or, insane.
I may be insane, but I am certainly in nobody's pocket. It seems to me this is not a cut and dry case. There are debates on both sides, and, virtually all of the science supporting climate change being caused by increased CO2 emmissions, specifically human caused CO2 emmissions seems to be the result of computer simulation.