Is no one allowed to have or express a politically incorrect personal opinion anymore? I tend to buck group-think myself on a regular basis — it’s part of how intelligent people think, and it’s very useful, even if the thoughts often aren’t politically correct.

Yes, it appears that global warming is a reality, and the evidence suggests that we humans could be at least partly responsible for it. But he’s absolutely correct when he says “I am not sure that it is fair to say that is a problem we must wrestle with.” No one is sure of that. It would be foolish for us not to try to do something about it, whether we’re sure or not, but he’s not arguing against that. His opinion is equally valid, and he shouldn’t feel any need to apologize for holding it.