Paul Krugman mentions the unthinkable in connection with increasing oil prices:

The consequences of that scarcity probably won’t be apocalyptic: France consumes only half as much oil per capita as America, yet the last time I looked, Paris wasn’t a howling wasteland. But the odds are that we’re looking at a future in which energy conservation becomes increasingly important, in which many people may even — gasp — take public transit to work.

Drive no more than the French! Take the bus! I believe that the survivors would envy the dead in that kind of world.