John McCain.Photo: twinkletoez6.  John McCain

U.S. senator from Arizona, former presidential nominee

Before: He cosponsored the first climate bills in the U.S. Senate in the mid-noughties, and made cap-and-trade a key part of his platform during his 2008 run for president. “Instead of idly debating the precise extent of global warming, or the precise timeline of global warming, we need to deal with the central facts of rising temperatures, rising waters, and all the endless troubles that global warming will bring,” he said in May 2008. “We stand warned by serious and credible scientists across the world that time is short and the dangers are great.”

After: In 2009, he derided cap-and-trade as “cap-and-tax.” In 2010, he questioned whether global warming is “man-made or natural.”