Michael Brune, head of the Sierra Club, said the negative impact of shale fracking is underestimated.

WSJ: As Fossil Fuels Rebound, Green Investing Takes a Hit

"The wildfires, storms and droughts we've seen over the past few years have shown us we need to make even steeper reductions in emissions that were proposed a few years ago, " says Michael Brune, executive director of the Sierra Club.

WSJ: Rise in U.S. Gas Production Fuels Unexpected Plunge in Emissions

Director Michael Brune and Robert F.

FORBES: Just Yelling "Stop!" is Not an Effective Energy Policy