CHARLOTTE, N.C. (MCT) — It was just six words, but when President Barack Obama gave a shout-out to global warming in his acceptance speech this month, he reintroduced an issue that had all but disappeared from the political debate.

“Climate change is not a hoax,” Obama said, an assertion that brought Democratic National Convention delegates to their feet, as he pledged to continue approaching energy policy in a way he said would “continue to reduce the carbon pollution that is heating our planet.”