Senator Hillary Clinton made headlines yesterday for her "bold and comprehensive plan" (her campaign's words) to reduce America's carbon emissions 80 percent by 2050. Recalling a visit to devastated forests near Barrow, Alaska, Clinton said, "There are no climate change skeptics inside the Arctic Circle."

Welcome aboard, Senator--most of your colleagues are already here. Senator Barack Obama, for one, outlined his commitment a month ago -- he didn't wait for Gore to snare his Nobel. And Senator John Edwards laid out a plan back in March.

I'll be honest, though -- I didn't know any of this. Nor did I realize that Clinton, Edwards, and Senator Christopher Dodd have paid to offset the carbon emissions generated by their campaign's SUVs and chartered planes until I read it in today's Washington Post. Maybe it's just me, but until very recently, the agenda-setters, whomever they are, seemed to have deemed global warming a third-tier issue in the presidential campaign, behind health care, immigration, the war. This despite the ruckus from Al Gore and the ominous scientific reports that are materializing with increasing frequency.

Anyway, now that Gore has his Peace Prize, that's starting to change (see, for instance, this recent effort from the New York Times). Needless to say, the plans are, for all practical purposes, identical -- all equally "bold and comprehensive." All would set up a cap and trade program that allows polluters to profit by reducing their emissions. All would use the sale of emissions permits under the program or redirect subsidies from oil companies to fund research into new energy projects and cushion the impact on consumers and automakers. All would dramatically raise consumption of renewable fuels and ruthlessly promote efficiency in cars, homes, and offices -- say goodbye to soft white incandescence and the Ford Explorer. (And say hello, perhaps, to the Ford Ka?) I won't bore you with further details, but you can peruse Edward's offering here, Obama's here, and Clinton's here.

I have only a couple questions. First why all the enthusiasm for convoluted cap and trade programs, which reward middlemen and brokers, but are difficult to administer and produce uncertain results? (To appreciate just how convoluted these programs are, and who might benefit from them, see this 2006 profile of Richard Sandor, founder of the Chicago Climate Exchange, which appeared in the New York Times Magazine.) Why not a straight carbon tax? Christopher Dodd has proposed such a measure, which lets all of us, producers and consumers alike, know up-front the cost of our carbon habit?

Secondly, how would any of the Democrats protect our industries from competitors (in, oh say, China) unburdened by similar greenhouse gas regulations? None of the plans put global warming into the context of the global economy. Indeed, increasingly in the last couple decades leaders in both parties have taken the sanctity of unfettered free trade as axiomatic. But unless the U.S. figures out how to package externalities like emissions into the trade regimes, we'll simply outsource our pollution to other shores, just as we outsource our jobs.