evidence: Environmental Protection Agency Administrator Scott Pruitt said Thursday he does not believe carbon dioxide is a primary contributor to global warming. "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 told CNBC's "Squawk Box." [...] "The planet's average surface temperature has risen about 2.0 degrees Fahrenheit (1.1 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide and other human-made emissions into the atmosphere," NASA and NOAA said in January.