BJORN LOMBORG: The Danish political scientist argues there are better ways to spend the money currently being spent on climate change prevention, including funding research and development for new energy technologies.

Scientific American: Is climate change a problem?

Bjorn Lomborg: Yes, it's a problem and it's man-made because of the burning of fossil fuels. We need to fix it but we need to fix it smartly.

BL: I don't agree with that assessment, already then I pointed out that it was a real problem. But for both books, it was the United Nations Intergovernmental Panel on Climate Change, which has thousands of scientists and experts determining what is the best knowledge we have of this problem. They have spent 17 years poring over data and are telling us that it is mankind that is the cause.

SA: What are sound estimates of the damage from climate change?

BL: Impact estimates range from a couple percentage points plus or a couple percentage points minus global gross domestic product [, or GDP]. There is a pretty big diversity in the estimates. The most likely estimate, if you look at Richard Tol and Gary Yohe's overview of all the peer-reviewed studies, is probably around 1 percent damage. Around 1 percent of our future GDP will be lost to climate change.

SA: What should be done about the problem?

BL: Basically, we need to stop burning fossil fuels before the end of the century. We need to find a way to deal with climate change within this century. Most people seem to say that means that we need to cut emissions right now. But cutting very much right now is a very expensive way of doing no good. Cuts like those in the Kyoto Protocol cost $180 billion annually and only postpone global warming by seven days at the end of the century. It's a very expensive way of doing very little. We need to cut the cost of cutting carbon dioxide. That is, we need to invent solutions, invest in research and development of noncarbon-emitting energy technologies like solar power and wind, carbon capture and storage as well as, most likely, fusion and fission.

SA: Where do cost estimates of the Kyoto Protocol, like $180 billion, come from?

BL: $180 billion is the average of all the macroeconomic energy models out of Stanford Energy Forum, the biggest collection of peer-reviewed published studies. It ranges from about $50 billion up to $450 billion. I take the average, which is probably a reasonable indicator. Since we never got the full Kyoto Protocol [with U.S. participation], it's very unclear what the actual cost would be. But $180 billion assumes that politicians worldwide are smart about how they are dealing with it. If they're not—like insisting that reductions happen inside their own country [instead of in whatever country they can happen most cheaply]—it could be much more expensive.

SA: Should this be viewed as an insurance or risk management problem?

BL: It's not an insurance question. You are not going to get your money back if climate change happens like you would if your house burns down. It could be a risk reduction policy. If there's a huge risk, it means that intuitively we should be buying more carbon cuts, but the ones that we have actually identified are not big risks. The last couple of predictions of big risks have been pretty poor. If you look back, we've had many predictions of these kinds of risks and they've all been wrong. The West Antarctic ice sheet collapsing was put to rest in 2001 IPCC report. El Niños getting much worse after 1998 was also wrong. We were worried about the Gulf Stream stopping and that was wrong. Now we worry about Greenland. Perhaps we should be a little more careful before we accept these as risks. But what if there is something lurking out there that could be bad? Well, that goes both ways. It could also happen that if we don't keep on pounding out CO₂ emissions it could be bad. Unless we have good information that tells us this will be a problem, then it's really not an argument for going either way.