It's not critical thinking. In both cases, one side presents evidence before their peers, and the other side says anything they can't understand must be stupid. We already have this side of the issue from the teenagers; why do we need to give it creedence by citing adults who still think this way?
The globabl warming sketpics have been presenting evidence for as long as the issue has been brought up. They have been labeled anti-science unfairly, by the media, certain NGOs, and the pro-warming scientists. They have been demonized and ridiculed rather than engaged and debated. Every time a skeptic demands to debate Al Gore, he refuses or invents some reason as to why his schedule cannot allow him to do so.
Al Gore is really irrelevant to global warming. I know a lot of folks think he "invented" the idea or something but that is silly... He's not a scientist and has nothing to do with the theory. It is like expecting Brad Pitt to give a public debate about the sociology behind China invading Tibet and their treatment of Tibetans.