President Trump's Environmental Protection Agency chief on Sunday admitted the climate is "changing" and that the "real issue" is how much human activity is affecting this "warming trend," including carbon dioxide emissions.

"Human activity contributes to that change in some measure. The real issue is how much we contribute to it," EPA administrator Scott Pruitt told "Fox News Sunday" host Chris Wallace.

Pruitt called for the U.S. to determine the amount people and companies have contributed to global warming, including the use and output of carbon dioxide and methane, an update of a previous comment he had made minimizing the impact of human activity.

"The issue is how much we contribute to it from a human activity perspective and then what can be done about it from a process perspective," Pruitt added.

Many conservatives acknowledge some degree of human contribution to global warming but question whether it is enough to warrant stringent regulations that could cost thousands of jobs.

However, Pruitt is being investigated by the Office of Inspector General for breaking the agency's rules for scientific integrity for making public statements on March 9 that carbon dioxide emissions were not "a primary contributor" to global warming.

Pruitt maintained the Obama administration's Clean Power Plan was not the proper way to respond to the global problem, claiming it was an attempt to "reimagine authority" on the policy.