He is promoting his new book but he is, none the less, putting a counter point to the current "We're all dooooomed" popular opinion.
"My topic today sounds humorous but unfortunately I am serious. I am going to argue that extraterrestrials lie behind global warming. Or to speak more precisely, I will argue that a belief in extraterrestrials has paved the way, in a progression of steps, to a belief in global warming. Charting this progression of belief will be my task today. "