Late last week, the head of the U.S. Environmental Protection Agency dismissed carbon dioxide emissions as being a primary cause of global warming. Speaking to CNBC, Scott Pruitt said: “I think that measuring with precision human activity on the climate is something very challenging to do and there’s tremendous disagreement about the degree of impact, so no, I would not agree that it’s a primary contributor to the global warming that we see." He went on to say "but we don't know that yet...we need to continue the debate and continue the review and the analysis."

That statement put Pruitt at odds with the agency he leads and it was widely condemned by scientists and environmental activists. The EPA's homepage cites carbon dioxide as the primary greenhouse gas contributing to climate change, a view backed by NASA and the National Oceanic and Atmospheric Administration. According to Pew Research, however, some Americans do agree with Pruitt's view. They found that 48 percent of people in the U.S. believe climate change is due to human activity, 31 percent attribute it to natural causes and 20 percent say there is no evidence to support it.