Concerned Scientists Vs. 'Superfreakonomics' Author In October, SuperFreakonomics author Steve Levitt spoke with host Scott Simon and outlined some provocative ideas for addressing the problem of global warming, like pumping sulfur dioxide into the upper atmosphere to cool down the earth. The Union of Concerned Scientists took issue, and Levitt is back to discuss his ideas with Peter Frumhoff, director of science and policy for the UCS.

Concerned Scientists Vs. 'Superfreakonomics' Author

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The debate continues over just how to address the world's environmental problems. Now, earlier this fall we spoke with Steve Levitt, co-author of "SuperFreakonomics," and that book proposed some provocative solutions, including figuring out how to pump sulfur dioxide into the upper atmosphere to help cool down the Earth.

The Union of Concerned Scientists wanted to discuss the global cooling described in "SuperFreakonomics," and so we're joined now from the studios of WBUR in Boston by Peter Frumhoff, director of science and policy for the UCS. Professor Frumhoff, thanks very much for being with us.

Professor PETER FRUMHOFF (Union of Concerned Scientists): It's my pleasure, Scott.

SIMON: And from the studios of WBEZ in Chicago, the author, co-author of "SuperFreakonomics," Steve Levitt, is back with us. Professor Levitt, thank you very much for being with us.

Professor STEVE LEVITT (Co-author, "SuperFreakonomics"): Well, thank you, Scott.

SIMON: And before we join the discussion, please, Steve Levitt, remind us of the kind of global warming solutions presented in the book that some people have questioned.

Prof. LEVITT: In our book we start from the premise that the current climate science conclusions are correct and the Earth is getting warmer and we need to do something about it. And from that point we ask the question: What is the cheapest and most effective way to cool the Earth quickly if we had to? And working with leading scientists, we've come to the conclusion that geo-engineering approaches, such as directing sulfur dioxide into the stratosphere or creating lightning clouds over the oceans are a cheaper, a quicker and a good short-term approach that will be more effective than carbon mitigation in the short run. Although, of course, carbon mitigation in the long run is probably still an admirable goal.

SIMON: Peter Frumhoff?

Prof. FRUMHOFF: Well, the - proposing a geo-engineering solution, for example, by increasing sulfate aerosols in the stratosphere, mimicking the actions of volcanoes, is basically substituting one big experiment with the Earth that we're driving - that is, our carbon pollution - with another, sending large quantities of sulfur dioxide into the atmosphere, into the stratosphere.

Most scientists who've looked carefully at this highlight that there are significant risks that Mr. Levitt and his co-author, Mr. Dubner, didn't mention in their book, making this neither a cheap nor easy nor simple solution to climate change.

SIMON: Well, Steve, let me get to pick up on that. Wouldn't there be some risk in loading the atmosphere with sulfur dioxide?

Prof. LEVITT: Of course there's risk, but the path we're on has risk as well. I mean, I think the idea that a bunch of leaders of nations are going to get together in Copenhagen and come up with a real solution to reducing carbon dioxide emissions that's meaningful and will have an effect in the short run is, I think, an unreasonable conclusion.

Even if we were to radically cut the amount of carbon dioxide we're emitting, we still would expect the Earth to warm for another 50 to 100 years because of the long half life carbon dioxide in the atmosphere.

So the most attractive feature of this approach is that, number one, it's very cheap. Carbon mitigation by contrast is extremely expensive. The estimates are we have to spend one to two percent of GDP per year for the next 50 years to deal with the problem. What I think the beauty of these geo-engineering solutions are - number one, you can do them immediately. They will have immediate affects on the temperature, whereas carbon mitigation will not. Number two, they're completely reversible. If we don't like what happens, we stop putting sulphur dioxide into the stratosphere and we will undo everything, we will see no trace of it within a year or two.

And number three, what it really does is it buys us time. Technology, there's almost, I would say, almost certain that we will be much more effective in taking carbon dioxide out of the air 50 years from now than we are now. So we want to buy time.

SIMON: Go head, Peter Frumhoff.

Dr. FRUMHOFF: So if I may, the illusion that it's cheap and easy is frankly nonsense. Increasing stratospheres, layers of sulphur dioxide, doesn't address the problem that carbon dioxide is causing by increasing the acidity of the oceans, as carbon gets absorbed in the oceans.

And it's frankly not reversible. If we need to do it, we put it in the atmosphere, we have to do it every year at increasing levels to offset the growing concentrations of carbon dioxide we wouldn't have reduced otherwise. And if we needed to stop doing it we'd all of a sudden have the large leap of increased heating associated with the carbon dioxide they wouldn't have otherwise reduced.

Dr. LEVITT: These geo-engineering solutions can be a stopgap, an insurance policy for the globe if things turned very ugly. I think it's very hard to justify an argument against that kind of investment.

Dr. FRUMHOFF: The challenge is that your book actually leads a casual reader to believe that it's a substitute for rather than a potential backstop for reducing our greenhouse gas emissions, and we're actually seeing the U.S. and China and other nations in advance of Copenhagen putting real emissions reductions targets on the table for meaningful political dialogue. That's important. It's critical to see that move forward.

To have though geo-engineering be the solution is a little bit like designing a health care system based on the emergency room. You may need it, but you don't want to go there as your first resort.

Dr. LEVITT: And if the U.S. were to meet the standards that Barack Obama has proposed, what will happen to the temperature of the Earth over the next 50 years?

Dr. FRUMHOFF: Well, we're going to see some warming. There's no doubt. In fact, all scientists recognize that we need to find a way to adapt to the warming that's already locked in. But we can constrain the worst impacts of global warming by reducing our emissions dramatically today. That's what the scientists are calling for.

And indeed, if we don't do it - even if you went to a geo-engineering approach such as you suggest, the other collateral impacts of carbon dioxide increase that we really can't avoid addressing if we're really to protect the planet for our kids and grandkids.

Dr. LEVITT: You simply cannot ignore the fact that spending one to two percent of GDP on reducing carbon emissions will have an enormous, enormous negative impact on future economies. The costs are enormous, the risks of doing nothing are also enormous. We need to think not just as climate scientists, not just environmentalists, but as economists when we face this important issue.

SIMON: Steve Levitt, University of Chicago economist and author of the new book "SuperFreakonomics," and Peter Frumhoff, director of Science and Policy with the Union of Concerned Scientists.

Gentlemen, thank you both very much.

Dr. FRUMHOFF: Thank you, Scott.

Dr. LEVITT: Thank you.

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