Contest - Steele's "What do you know about global warming?" quiz post

Local contrarian Russ Steele has a blog post up plugging a "What do you know about global warming?" quiz.

I went through the first few questions, and there's a hole in its logic that you can drive a Prius through.

Can you spot it? First person to do so gets a free coffee (from me) at Java John's.

(to make this one easy, here's a hint)