10/21/2010 02:32 pm ET | Updated May 25, 2011

Sparring with Bjorn Lomborg -- Round II

My last encounter with Bjorn Lomborg, author of The Skeptical Environmentalist, was a Harvard debate shortly after he published that book. Now he's followed up his newest book, Cool It, with a movie of the same title, and the Commonwealth Club here in San Francisco agreed to host us for a second debate.

Lomborg has boiled down his message -- perhaps for cable talk shows -- to a few simple points: It's cheaper and safer to accept the risks of global warming than to kick our addiction to carbon energy. Trying too hard to solve the climate crisis will cost too much and interfere with solving more immediate problems like poverty, disease, and conflict. And, lastly, if climate change really does turn out to be a big problem, the only solution will be to go to extreme geoengineering.

Somehow, just building a clean-energy economy didn't make his list of possible solutions. He said his economist friends "all" agree that it's just "too expensive and wasteful." He did score good points on the weaknesses of both the Kyoto Protocol and current versions of cap and trade -- even resorting to quoting climatologist Jim Hansen as an ally.

But Lomborg stayed firmly rooted in the abstractions of macroeconomics, declining to challenge me when I pointed out that replacing the entire U.S. fleet of coal-fired power plants with cleaner energy (efficiency, renewables, and natural gas) would cost about as much as the $100 billion in medical costs that's imposed by those plants every year. The climate benefits would be free.

Similarly, while Lomborg said that renewables like wind, biofuels, and solar are so wastefully expensive that we shouldn't deploy them until more research brings their costs down, he was silent when I pointed out that for the 1.5 billion people in the world who aren't on the grid, solar is already cheaper than the diesel generators and kerosene they're currently using.

Lomborg claimed that smarter public policy would be a better way to avoid disastrous floods than curbing carbon emissions would be -- although he admitted that global warming will make flooding much worse.

But Lomborg had no answer when I asked what simple public-policy solutions would avoid the flooding of rice paddies in the coastal areas of Bangladesh, or could have averted this year's catastrophic floods in Pakistan. (Actually, there is an answer to the second question -- if Pakistan had preserved instead of devastating its forests, the flooding crisis would have been greatly diminished -- but Lomborg astonishingly dismissed the idea of protecting forests globally as "just too expensive.")

What does he favor instead? Well, more research into better low-carbon technology, which I applaud. But then he jumps immediately to research on extreme geoengineering -- things like dumping massive quantities of "white" air pollutants and acid-sulfur particles into the atmosphere. This is not just risky -- it's foolish. It's like refusing to fund a local fire department to protect my house, while hiring an expensive architect to plan what I might replace my house with if it does burn down.

How does Lomborg justify this? By saying that if the extreme consequences of climate change, like melting the Antarctic ice cap, come to pass, then the only thing that will work fast enough might be geoengineering. It's hard to know if he really believes this -- or if geoengineering, like clean-tech research, is fundamentally just a way to look like he is for something, even as he resolutely defends our addiction to carbon.