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."
"But we don't know that yet. ... We need to continue the debate and continue the review and the analysis."
The statement contradicts the public stance of the agency Pruitt leads. The EPA's webpage on the causes of climate change states, "Carbon dioxide is the primary greenhouse gas that is contributing to recent climate change."
Pruitt's view is also at odds with the conclusion of NASA and the National Oceanic and Atmospheric Administration.
"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.
Sen. Brian Schatz, D-Hawaii, co-chair of the Senate Climate Action Task Force, slammed Pruitt for his comments, calling his views "extreme" and "irresponsible."
"Anyone who denies over a century's worth of established science and basic facts is unqualified to be the administrator of the EPA. Now more than ever, the Senate needs to stand up to Scott Pruitt and his dangerous views," he said in a statement.