It’s been almost a century since the British economist Arthur Pigou floated the idea that turned his name into an adjective. In “The Economics of Welfare,” published in 1920, Pigou pointed out that private investments often impose costs on other people. Consider this example: A man walks into a bar. He orders several rounds, downs them, and staggers out. The man has got plastered, the bar owner has got the man’s money, and the public will get stuck with the tab for the cops who have to fish the man out of the gutter. In Pigou’s honor, taxes that attempt to correct for this are known as Pigovian, or, if you prefer, Pigouvian (the spelling remains wobbly). Alcohol taxes are Pigovian; so are taxes on cigarettes. The idea is to incorporate into the cost of what might seem a purely personal choice the expenses it foists on the rest of society.

Illustration by Tom Bachtell

One way to think about global warming is as a vast, planet-wide Pigovian problem. In this case, the man pulls up to a gas pump. He sticks his BP or Sunoco card into the slot, fills up, and drives off. He’s got a full tank; the gas station and the oil company share in the profits. Meanwhile, the carbon that spills out of his tailpipe lingers in the atmosphere, trapping heat and contributing to higher sea levels. As the oceans rise, coastal roads erode, beachfront homes wash away, and, finally, major cities flood. Once again, it’s the public at large that gets left with the bill. The logical, which is to say the fair, way to address this situation would be to make the driver absorb the cost for his slice of the damage. This could be achieved by a new Pigovian tax, on carbon.

In the past several weeks, as New York and New Jersey have continued to dig out from under the debris left by Hurricane Sandy, the possibility of a carbon tax has come to seem more likely than ever, that is, not very likely, but also not entirely out of the question. The reason for this is not so much the terrible cost of the storm, now estimated at more than sixty billion dollars. (The other day, Governor Andrew Cuomo said that Sandy had caused forty-two billion dollars’ worth of damage in New York State alone.) It’s that, as Washington edges toward the fiscal cliff, it has become obvious to just about everyone, except maybe House Republicans, that Washington needs more revenue.

Not long ago, the Congressional Research Service reported that, over the next decade, a relatively modest carbon tax could cut the projected federal deficit in half. Such a tax would be imposed not just on gasoline but on all fossil fuels—from the coal used to generate electricity to the diesel used to run tractors—so it would affect the price of nearly everything, including food and manufactured goods. To counter its regressive effects, the tax could be used as a substitute for other, even more regressive taxes, or, alternatively, some of the proceeds could be returned to low-income families as rebates (although, of course, this would cut down on the amount that could go toward deficit reduction).

Shortly after the C.R.S. report came out, the conservative American Enterprise Institute teamed up with its liberal counterpart, the Brookings Institution, to host a seminar on the subject, a collaboration that prompted the Wall Street Journal’s Web site to declare, “CARBON TAX IDEA GAINS WONKISH ENERGY.” “I think the impossible may be moving to the inevitable without ever passing through the probable,” Bob Inglis, a former Republican representative from South Carolina and a carbon-tax backer, told the Associated Press.

Perhaps because a carbon tax makes so much sense—researchers at M.I.T. recently described it as a possible “win-win-win” response to several of the country’s most pressing problems—economists on both ends of the political spectrum have championed it. Liberals like Robert Frank, of Cornell, and Paul Krugman, of Princeton, support the idea, as do conservatives like Gary Becker, at the University of Chicago, and Greg Mankiw, of Harvard. (Mankiw, who served as chairman of the Council of Economic Advisers under President George W. Bush and as an adviser to Mitt Romney, is the founding member of what he calls the Pigou Club.) A few weeks ago, more than a hundred major corporations, including Royal Dutch Shell and Unilever, issued a joint statement calling on lawmakers around the globe to impose a “clear, transparent and unambiguous price on carbon emissions,” which, while not an explicit endorsement of a carbon tax, certainly comes close. Even ExxonMobil, once a leading sponsor of climate-change denial, has expressed support for a carbon tax. “A well-designed carbon tax could play a significant role in addressing the challenge of rising emissions,” a spokeswoman for the company said recently in an e-mail to Bloomberg News.

One key player who has not embraced the idea is Barack Obama. The White House spokesman, Jay Carney, was asked about the tax last month, en route, as it happens, to visit storm-ravaged areas of New York with the President. “We would never propose a carbon tax, and have no intention of proposing one,” Carney told reporters. This was taken by some to mean that Obama was opposed to the tax and by others to mean just that he was not going to be the one to suggest it.

In either case, the White House is making a big mistake. Pigovian taxes are rarely politically popular—something they have in common with virtually all taxes. But, as Obama embarks on his second term, it’s time for him to take some risks. Several countries, including Australia and Sweden, already have a carbon tax. Were the United States to impose one, it would have global significance. It would show that Americans are ready to acknowledge, finally, that we are part of the problem. There is a price to be paid for living as we do, and everyone is going to get stuck with the bill. ♦