EPA Chief Gina McCarthy told the Senate this week that the Clean Power Plan’s impact on climate change is “not the benefit that you’re trying to establish or quantify.”

Montana Sen. Steve Daines pressed her to evaluate the cost-benefit analysis of the policy, which is expected to have a multi-billion dollar economic effect, raise utility prices by double digits in most states, and which has already cost hundreds of coal jobs.

The senator pointed to an analysis by the Cato Institute, which used EPA modeling and discovered that if the U.S. slashes carbon emissions as the Clean Power Plan mandates, the impact on global warming is less than two-hundredths of a degree Celsius by 2100.

McCarthy side-stepped the cost-benefit analysis, arguing, “We are trying to get domestic and international agreements which this Clean Power Plan has helped to initiate to get worldwide response to what is essentially a worldwide problem.”

But, as we’ve noted before, the world’s biggest emitters have little reason to cut back on carbon—and, for the sake of their impoverished citizens, much reason to stick to the status quo. The U.S.-China emissions deal is heavily one-sided in Beijing’s favor and to our detriment, while the Paris Climate Conference is nonbinding and unenforceable.

It’s worth watching the jaw-dropping McCarthy-Daines exchange in its entirety.