mdsolar writes: 'Paul Krugman, who won a Nobel Prize for understanding world trade, has proposed carbon tariffs as a way to get China to cut greenhouse gas emissions. He wrote, "China is enormously dependent on access to advanced-country markets — a lot of the coal it burns can be attributed, directly or indirectly, to its export business — and it knows that it would put this access at risk if it refused to play any role in protecting the planet. More specifically, if and when wealthy countries take serious action to limit greenhouse gas emissions, they're very likely to start imposing "carbon tariffs" on goods imported from countries that aren't taking similar action. Such tariffs should be legal under existing trade rules — the World Trade Organization would probably declare that carbon limits are effectively a tax on consumers, which can be levied on imports as well as domestic production. Furthermore, trade rules give special consideration to environmental protection. So China would find itself with strong incentives to start limiting emissions." As I read it, Article XX of the General Agreement on Tariffs and Trade does indeed allow us to unilaterally impose tariffs on China.'