U.S. Secretary of State John Kerry attracted some attention the week before last by describing climate change as "perhaps the world's most fearsome weapon of mass destruction." Another part of his remarks, though, was just as revealing.
After saying we should not listen to those who deny that human activity is warming the globe, he said: "Nor should we allow any room for those who think that the costs associated with doing the right thing outweigh the benefits. There are people who say, 'Oh, it's too expensive, we can't do this.' No. No, folks."
For Kerry, then, the benefits of reducing carbon emissions so obviously exceed the costs that no debate on the question is necessary or even tolerable. But he's wrong. The cost-benefit calculation is the weak point in the case for reducing carbon emissions. It's possible to reject that case without questioning the science behind it.