There's a hard question that must asked of every plan that would combat climate change: how do you get developing countries, particularly China and India, to sign on to an emission control regime? Those countries, after all, have a fair point when they argue that most of the CO2 currently warming the planet rose from the tailpipes and smokestacks of Western nations--it's unfair of the West to change the rules after a 150-year head start. But without their participation, self-imposed carbon constraints in the industrialized world are bound to fail as manufacturers simply relocate to Asia. In fact, carbon dioxide emissions could actually increase.

Democrats have never properly explained how they would induce the Asian tigers (or Mexico or South Africa) to cooperate. Democrat Barack Obama promises only to "exert maximum pressure on China and India to do their part and make real commitments of their own" -- good luck with that! But there is simple solution: make trade contingent on tough carbon emission rules. Price the tariff on the cost to abate carbon emissions, plus a little extra for our trouble. The revenue raised could go to foster renewable fuels or conservation strategies, or fund tax credits to firms that do the most to reduce their carbon footprint.

The objection to such a fiendishly elegant solution has always been, I suppose, "free trade," and, frankly, I've never understood it. Somewhere along the way, trade became sacrosanct -- an end in itself, not a means to other ends (like, for example, heath and prosperity). Even mainstream Democrats, as beholden to corporate bankrollers as Republicans, have been willing to sacrifice the environment at free trade's altar.

That's why it was refreshing to hear Republican John McCain buck the conventional wisdom on regulating carbon this afternoon. McCain favors a markedly less-ambitious cap-and-trade system than his Democratic rivals (I'll be generous toward Senator Clinton), but speaking the Portland, Oregon, headquarters of Vestas - American Wind Technology*, he appeared far more ambitious in taking on India and China. "If the efforts to negotiate an international solution that includes China and India do not succeed, we still have an obligation to act," McCain said (or at least intended to say -- I'm working off the prepared remarks that were emailed to me this morning). "If industrializing countries seek an economic advantage by evading those standards, I would work with the European Union and other like-minded governments that plan to address the global warming problem to develop a cost equalization mechanism to apply to those countries that decline to enact a similar cap."

Mechanism, shmechanism -- it sounds like a tariff to me. And I say, great. I hope the Democrat(s) embrace McCain's position. Perhaps it's like Nixon going to China -- just as it took a rabid anti-communist to normalize relations with Red China, it might require a staunch free trader to take free trade off its pedestal.

*Vestas, the world's largest wind turbine manufacturer, is a Danish company, and Denmark itself is a leader in the wind industry: in 2006, Danish firms controlled about 40 percent of the market. How did this happen? Simple: beginning in the 1970s, the country invested in wind R&D and consumer subsidies to support the young industry. In 2006, the industry employed 22,000 Danes and had worldwide sales of about $8.2 billion -- not a bad return on an investment that by 2002 had totaled just $300 million.