The head of the Environmental Protection Agency said Friday that coal communities could get left behind as the energy market shifts away from coal to other cleaner resources.

"On the whole, what's happened is jobs continue to grow," EPA administrator Gina McCarthy said addressing a climate conference in Washington. "What happens, though, is some communities may get left behind."

"You don't change the entire dynamics of the economics for those communities, or deny they exist, you invest in those communities so they can continue to have opportunities for moving forward," she said.

She was answering questions posed by host Bill Nye, on what happens to coal communities under her agency's climate regulations. McCarthy said the effects on coal communities have been due to the cost of owning and operating coal plants. Some coal operators don't want to make the changes to comply with pollution controls and decide to shut down. "But that's the choice of the market," she said.

She said the transition in those states has been underway for decades since the 1980s when the more economical coal was mined out. Now they are going after deeper coal that is more expensive to mine, and its making the economics harder. "The market right now is saying it isn't competitive."

Still, she did not write off coal. She said "coal will be around for a while. But the challenge we have is to actually invest in those communities."

She said the administration wants to send money to West Virginia and Kentucky, through its Power Plus program, to revitalize those regions hardest hit by thousands of coal layoffs.

The program would help workers transition to other jobs, while making investments in digital infrastructure like broadband.