As millenarian prophecies go, “the peak is nigh” does not pack the same doom-laden punch as a promised “end”. Except, that is, in oil circles.

Oil resources are finite. “Peak oil” theorists posit that about half of all the world’s crude has been used and that output will soon peak prior to an irreversible decline. Such thinking has helped propel crude to the $100 per barrel level it touched yesterday. Conventional oil fields are like champagne bottles: once “opened”, pressure forces out some of the contents. Eventually field pressure drops and, barring using such techniques as re-injecting gas, output inevitably declines. Back in the 1950s, Marion King Hubbert, a US geoscientist, correctly forecast – to within a few years – when output in the US’s lower 48 states would peak (it was 1970). The “Hubbert curve” is a totem of peak oil theorists.