Say David is right and the 2008 presidential election comes down to Obama vs. McCain. That means we're looking at historic, though frankly probably inadequate, climate-change legislation.

On foreign policy, McCain has been an abysmal apologist for the Iraq debacle. That doesn't bode well. But Obama, to prove he's not a weak-kneed liberal, might be goaded into taking crudely aggressive stances -- just as Bill Clinton seemed to take a poke at Iraq every time Monica-gate took a turn for the worse.

On farm and food policy, they look like a wash. At least McCain has dared speak bluntly now and again on the fraud that is corn-based ethanol (although he has cravenly reversed that position). Obama hails from a Big Ag state, loves ethanol, and once even (according to Ken Sliverstein in the November 2006 Harper's, unavailable online) hitched a ride on the Archer Daniels Midland corporate jet.

I'm wondering, given the viable options on the table, if all the machinations leading up to the 2008 election might be more noise than signal.

Rather than obsessing over who's up and who's down, we might more usefully spend our time thinking real hard about how to thwart odious long-term trends playing out before our eyes: like, say, the rise in consumption of noxious fuel sources like coal, nuclear, and tar sands in response to high oil prices.