The Energy Grid

China, for example, is still growing faster than just about anyone else, so not only should they be able to afford the extra cost of eschewing coal, but it's paramount that they do it. And the best way to bring that about is to get them to agree to a global treaty that effectively prices coal (and oil and gas) out of everyone's price range.

No one wants to be denied the right to shop at Wal-Mart, of course. Even those who think of themselves as far too sophisticated to ever grace its aisles would bristle at being told they now can shop only at Whole Foods. And the vast majority of China's population can still only dream about being able to afford a Wal-Mart lifestyle. (Don't let the urban-focused media coverage fool you.)

But if those of us who really can afford the more expensive energy options put our money where our mouths are, then at least we stand a chance of convincing the rest of the world to do the same. A carbon tax or sufficiently tight cap-and-trade system can, at least in theory, force us off our fossil-fuel habit. It's all about setting an example.

If that doesn't do the trick, the Wealthy West can then impose trade tariffs on those nations who refuse to get with the program. Indeed, the American Clean Energy and Security Act comes with just such an option, inserted at the very last minute before Friday's vote. Barack Obama doesn't like it much, arguing this week that "we have to be very careful about sending any protectionist signals out there."

But the fact is the international free trade regime already makes allowances for this sort of thing, as Reuters columnist John Kemp lays out:

LONDON, June 26 (Reuters) - Nothing in international trade law would prevent countries that introduce carbon taxes or cap-and-trade programmes from supplementing them with excise duties, tariffs or other measures on imports from countries that don't.

The absence of a single international carbon price risks causing significant trade distortions as well as undermining the effectiveness of emissions reduction programmes if business migrates from countries with a high carbon price to ones with a low or zero one.

So the question of whether control programmes can be buttressed with measures such as tariffs and other restrictions to "level the playing field" and prevent "carbon leakage" is crucial to the success of the system as well as its political acceptability.

While the issue of "greenhouse tariffs" has aroused bitter opposition from developing countries such as India and China, the rules are fairly clear, and the World Trade Organisation (WTO) has helpfully set them out in a joint report on "Trade And Climate Change" published in conjunction with the United Nations Environment Programme (http://www.wto.org/english/res_e/booksp_e/trade_climate_change_e.pdf).

Of course, such tariff barriers would effectively kill Wal-Mart's business model. The political costs of such action would be high. But anyone who thinks that business as usual is still an option isn't playing with a full deck.

And once we have some kind of level playing field, it shouldn't be hard to interest the developed world in supplying clean tech to the developing world. Not if that's the only way to get us all into a position where we don't need those tariffs anymore.