Cars, bombs, and climate change

What especially bugs my critics is the idea that cutting carbon is a cure that is worse than the disease - or, to put it in economic terms, that it would cost far more than the problem it is meant to solve. "How can that possibly be true?" they ask. "After all, we are talking about the end of the world. What could be worse - or more costly - than that?"

They have a point. If we actually face, as Al Gore recently put it, "an unimaginable calamity requiring large-scale, preventative measures to protect human civilization as we know it," then no price would be too high to pay to stop global warming in its tracks. But are the stakes really that high?