You think if they testified for the regulations they would have strong opinions on this.
Check it out:

All four former Environmental Protection Agency (EPA) administrators appointed by Republican presidents who testified in favor of the agency’s proposed power plant regulations at a Senate subcommittee hearing last week did not respond when asked if they agreed with President Obama that global warming was accelerating.

Sen. Jeff Sessions (R-AL) asked former EPA heads William Ruckelshaus, Christine Todd Whitman, William Reilly and Lee Thomas whether they agreed with Obama’s previous statements that the Earth is warming faster than previous predictions.