Another U-Turn

Flip-flop chatter over Romney's global warming stance heats up after Bay Stater tells Pittsburgh crowd Fri. "we don't know what's causing climate change."

In June, Romney said humans were partly responsible: "I believe that humans contribute to that. I don’t know how much our contribution is to that, because I know that there have been periods of greater heat and warmth in the past, but I believe we contribute to that."