During a townhall meeting in Lebanon, New Hampshire, the former Massachusetts governor was asked whether he believed humans were contributing to temperatures creeping upwards. Romney responded that humans play some role, but that it's not clear what.
"Do I think the world's getting hotter? Yeah, I don't know that but I think that it is," Romney said. "I don't know if it's mostly caused by humans."
"What I'm not willing to do is spend trillions of dollars on something I don't know the answer to," he added."
I generally like Romney and find him to be quite affable. However it must be frustrating to even his most ardent supporters that the guy will so easily change his position if he thinks that a different perspective would improve his standing.
Don't get me wrong, in real world experience alone the guy is head and shoulders above someone like Obama who never so much as managed a hot dog stand before becoming president. Actually, almost any of the GOP declared candidates would be better than Obama IMO.
EDIT: Special thanks to Mr. Day for posting the latest real science on the subject from researchers in Switzerland which seems to point towards climate change being more heliocentric (as opposed to anthropogenic) than was previously thought possible.