THE DISPUTE: There's a split between leading environmental groups over whether the boom in natural gas drilling, or fracking, will help or hurt efforts to fight climate change. That's because while natural gas is a far cleaner burning fuel than coal, the methane in the gas is also a potent greenhouse gas. If too much methane leaks into the atmosphere, that negates the benefits over coal.
THE REACTION: Environmentalist Michael Shellenberger said the EPA revisions are "great news" and "kind of an earthquake." But 350.org founder Bill McKibben said the news doesn't change the fact that natural gas is still a fossil fuel that emits some greenhouse gas.