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We often talk about climate change as a matter of science, but the biggest questions are really about money: How much would it cost to fix it and what price we will pay if we don't. Well, we're about to meet the man who invented the field of climate economics. And he says the best way to tackle climate change is also through dollars and cents. William Nordhaus wrote a book that lays out his idea in simple terms.
NPR's Richard Harris took a trip to Yale University to talk to this celebrated economist.
RICHARD HARRIS, BYLINE: The buzz here on the Yale campus is that it's only a matter of time before Bill Nordhaus lands the Nobel Prize. But there's not a trace of haughtiness in the gentle, 72-year-old's demeanor.
BILL NORDHAUS: Come on upstairs.
HARRIS: He tromps up the staircase of this 19th century building in his mud boots. Silver hair sweeps across his high brow. Nordhaus' expansive suite is part parlor, part library and part office. He's been at Yale since 1967. And as we settle into a couple of chairs, he says his ideas about climate change date back to 1974, when he was a research scholar in Austria.
NORDHAUS: And I happened to share an office with a climatologist. And I was doing energy research. And he said: Well, you know, this is where energy research is going to be going. And I said, well, OK, tell me about it. And that's how it started.
HARRIS: Some scientists were starting to think about climate change back in the early '70s, but Nordhaus says not so in the world of economics.
NORDHAUS: It was a zero on the intellectual Kelvin scale in economics. There was nothing at that point.
HARRIS: Nordhaus started to grapple with the basic question. Climate change was looming because people were burning cheap fossil fuels. Carbon dioxide is building up in the atmosphere and each ton increases the risk of sea level rise, shifting climate, and other changes that are likely to cost a huge amount of money to address in the future. Right now, nobody pays for that, and it wasn't even clear what the price should be.
NORDHAUS: When we did our first calculations they actually spun out these shadow prices. And I remember looking at them and trying to think of what in the world does that mean.
HARRIS: He realized that those shadow prices actually represented the cost of putting carbon dioxide into the atmosphere. And with that, climate change suddenly became a problem that could be attacked with the tools of economics.
NORDHAUS: Actually from an economic point of view, it's a pretty simple problem.
HARRIS: If people would simply pay the cost of using the atmosphere as a dump for carbon dioxide, that would create a powerful incentive to dump less and invest in cleaner ways to generate energy. But how do you do that?
NORDHAUS: We need to put a price on carbon so that when anyone, anywhere, any time does something that puts carbon dioxide in the atmosphere there's a price tag on that.
HARRIS: After that initial inspiration, a lot of Nordhaus' work has been figuring out how big a price we should pay and what form it should take. It could be a carbon tax, preferably in place of other taxes. Or it could be a cap-and-trade system, where polluters buy and trade the rights to put carbon in the air. California and Europe are starting to put policies like this in place.
NORDHAUS: The real point of the pricing is not to gouge people, not to extract resources from people. It's to tilt the playing field in such a way that people, firms, governments, everybody move toward carbon free or low carbon activities.
HARRIS: Nordhaus has laid out how to do this in a book, called the "Climate Casino." The not-so-subtle point of the title is that we're gambling with our future if we don't do anything about climate change. And Nordhaus knows the challenge isn't the economics, it's us. His studies show that it makes economic sense to start paying the price now, even though the benefits would be decades away.
NORDHAUS: That's a pretty tough one because we're going to have to be grownups, I think. There are lots of things we do where the investments come way, way in the future. Educating four-year-olds, I mean that's an investment that goes way in the future as well.
HARRIS: But for this to affect the climate, he finds that at least half of the planet needs to work together, or it will be all pain and no gain.
Nordhaus is hardly a saber-rattler on this subject. Though he sees the potential for very serious problems down the road, he still says that global warming can actually be good for agriculture, at least up to a point. And he says we shouldn't do any more to address climate change than what makes economic sense, even if that means letting the planet warm up more than the international target of two degrees Celsius.
I now that sometimes environmentalists get frustrated that you sound calm and they don't feel calm.
NORDHAUS: Well, what can I say about calm? What I like to think of the economics as a cool head in the service of a warm heart, and that's my approach to this.
HARRIS: People who have been dubious about climate change have, over the years, quoted Nordhaus' work to argue that it doesn't require urgent action. But lately, urgency has been creeping into Nordhaus' voice.
NORDHAUS: At some point you move from calm to concerned. I'm not at panic, but I'd say there are some pretty deep concerns about what's going on, particularly at the slow pace of the steps that countries are taking to deal with climate change.
HARRIS: His numbers show that the world can actually afford to take the steps we need to rein in climate change, provided that we make smart choices about how to do it.
Richard Harris, NPR News.