President Trump's head of the Environmental Protection Agency says he does not believe that carbon dioxide is a major cause of global warming.
"I believe 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," Pruitt said.
Those statements are at odds with an overwhelming body of scientific evidence showing that humans are causing the climate to warm by releasing CO2 into the atmosphere. The view that CO2 is a major heat-trapping gas is supported by reams of data, included data collected by government agencies such as NASA and the National Oceanic and Atmospheric Administration.
Pruitt's views are consistent with earlier comments he has made on the topic of climate change. As attorney general of Oklahoma, Pruitt often claimed that there was scientific uncertainty over whether humans are changing the climate.