This just in: Saving the planet would be cheap; it might even be free. But will anyone believe the good news?

I’ve just been reading two new reports on the economics of fighting climate change: a big study by a blue-ribbon international group, the New Climate Economy Project, and a working paper from the International Monetary Fund. Both claim that strong measures to limit carbon emissions would have hardly any negative effect on economic growth, and might actually lead to faster growth. This may sound too good to be true, but it isn’t. These are serious, careful analyses.

But you know that such assessments will be met with claims that it’s impossible to break the link between economic growth and ever-rising emissions of greenhouse gases, a position I think of as “climate despair.” The most dangerous proponents of climate despair are on the anti-environmentalist right. But they receive aid and comfort from other groups, including some on the left, who have their own reasons for getting it wrong.

Where is the new optimism about climate change and growth coming from? It has long been clear that a well-thought-out strategy of emissions control, in particular one that puts a price on carbon via either an emissions tax or a cap-and-trade scheme, would cost much less than the usual suspects want you to think. But the economics of climate protection look even better now than they did a few years ago.