After the credit squeeze, are we heading for an energy crunch? Look at the oil price, which has collapsed to less than $60 a barrel from its July record of $147, and this might seem improbable. The financial crisis and the gathering global economic storm have sapped world petroleum demand, leaving markets awash with crude. The long-term danger lies in the effect lower prices have on investment decisions by producing countries and the oil majors. When the world recovers, it may find energy a scarcer resource.

The recent bull run in oil, as in other commodity markets, was always unsustainable. A weakening dollar was a substantial trigger for a flight by investors to commodities in 2007. When the US currency recovered, oil prices fell. The belief, too, that emerging economies had decoupled and would somehow be immune from the US downturn has proved false. The oil price remains subject to cyclical swings in supply and demand.