Tackling climate change -- a bargain

That's the headline on an article in The Economist about the third report from the Intergovernmental Panel on Climate Change. The report concludes that to stabilize CO₂ concentrations at 535-590 parts per million (substantially above the current level of ca. 380ppm -- source) would reduce the average annual growth of GDP by less than 0.1% (p. 15), corresponding to a carbon price of $20-50 per metric ton. The Economist concludes:

The world would barely notice such figures; so one might think that climate change can be easily sorted. The problem, of course, is that the numbers work only if they are applied globally. If a few countries – even a few big countries – adopt a carbon price, it will make little difference. All the world's big emitters need to do it. Which brings the world straight back to the problem that sank Kyoto. No country alone can make a difference, and it is in every country's interest to ensure that everybody else bears the burden. As the IPCC report convincingly argues, the technology and the economics of this problem are easily soluble. It is the politics that is so difficult.