Entergy CEO: Maybe trace amounts of carbon dioxide will kill us all

Entergy CEO steps up demand that the industry deal with global warming

"I can think of no time in history when the planet is in as much peril as it is today," he said. "We were not supposed to be facing the possibility of mass extinctions in anybody's lifetime ... but here we are."

Leonard dismissed as a "trick answer" the arguments of critics of climate change science that it's uncertain whether the effects of global warming will be good or bad.

"What we can't be certain about is how bad is it going to be: Are we going to end up with 25 percent of species extinct? Or 50 percent? Is man going to be one of those species?" he said. "There are no good outcomes at all," he said.