In October, when Romney was still fighting for the GOP presidential nomination, he was unequivocal about climate change: "My view is that we don't know what's causing climate change on this planet. And the idea of spending trillions and trillions of dollars to try to reduce CO2 emissions is not the right course for us." Now that he's seeking to appeal to the broader electorate, he has dialed that back a little; in a statement this month posted on the website Sciencedebate.org, he acknowledged that human activity is contributing to global warming but maintained that "there remains a lack of scientific consensus on the issue," so further research is needed. There is an overwhelming scientific consensus that the planet is warming and that human activity is the cause.

Above: Romney addresses the Republican National Convention on Aug. 30 in Tampa, Fla.

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