In last night's third debate, which was supposed to be about domestic issues, I didn't hear a single mention of oil. Not one word about those three little letters. Yet oil — supply, cost and dwindling geological reserves — is the greatest domestic crisis we are likely to face in this decade: Greater than the deficit, jobs, taxes, health care, social security, you name it. Even greater than all of them combined.

I'm not making this up. David Owen is. In a fascinating article in the current New Yorker, "Green Manhattan" (unfortunately not online), which makes the counterintuitive case that our big cities are more energy efficient and friendlier to the environment than our sprawling suburbs, Owen quotes a warning from "Out of Gas: The End of the Age of Oil," by David Goodstein, a professor at the California Institute of Technology.

With roughly half the planet's total petroleum supply already consumed, according to Goodstein's book, "the world will soon start to run out of conventionally produced, cheap oil," and we've got less than 10 years to solve the problem. As Owen writes, "a devastating global petroleum crisis will begin not when we have pumped the last barrel out of the ground but when we have reached the halfway point, because at that moment, for the first time in history, the line representing supply will fall through the line representing demand," and "we will probably pass that point within the current decade, if we haven't passed it already."

The result is that "various well-established laws of economics are about to assert themselves, with disastrous repercussions for almost everything." (Italics added.) And here's Goodstein's capper: "Civilization as we know it will come to an end sometime in this century unless we can find a way to live without fossil fuels." Does that need repeating? I think it does: "Civilization as we know it will come to an end sometime in this century unless we can find a way to live without fossil fuels." If that seems far away to you, how about this? We'll be starting down that road by 2015.