A so-called carbon tax would put a price on any carbon released into the atmosphere. But even for the greenest voters, a tax increase that would help the environment is likely to be a hard sell. "There's no question that, politically, tax is a four-letter word. But we have to really convince voters that this is not an overall tax increase; it's really a tax shift," said Gregory Mankiw, an economist and former chairman of President Bush's Council of Economic Advisors.
Mankiw, who supports a tax, speaks with John Ydstie.