Just because I'm a cynic, just because I know a good scientist questions everything, doesn't mean I actually have to do that. If three plumbers tell me I have a plumbing problem, I sometimes just bow to their expert opinions. As I understand it, the vast majority of experts on climate think that humans are causing global warming. In this case, I'm willing to take them at their word. Could the vast majority of experts be wrong, absolutely, there are previous examples (plate tectonics for a 20th century example).