AS THE developed-world economy tries to gain momentum, it faces a persistent headwind. The oil price remains stubbornly over $100 a barrel, acting like a tax on Western consumers. Some blame the high price on evil speculators—Barack Obama unveiled plans to increase penalties for market manipulation on April 17th. But there is a simpler explanation: that supply is inadequate to keep up with rising demand.

The concept of peak oil—the idea that global crude production may be at, or close to, its limit—is far from universally accepted. One leading asset manager talked recently of the world being “awash with energy” because of the exploitation of American shale gas. Nevertheless, oil is still the main fuel for cars and trucks. And crude output (as opposed to alternatives such as biofuels and liquids made from gas) has been flat since 2005.

A number of countries (including Britain, Egypt and Indonesia) have turned from net oil exporters into importers in recent years. And although rich countries have curbed their energy-guzzling a little, demand continues to surge in emerging markets.

This has left the oil market very vulnerable to temporary supply disruptions, such as the war in Libya. Speaking at a conference in Dublin this week, organised by the Institute of International and European Affairs and the Association for the Study of Peak Oil and Gas, Chris Skrebowski, a consulting editor of Petroleum Review, argued that spare capacity in the oil market could be eroded by 2015.

The peak-oil concept was devised by the late M. King Hubbert, who correctly predicted in 1956 that oil output in the lower 48 states of America would peak by around 1970. At the conference Michael Kumhof, an economist at the International Monetary Fund, presented the findings of a forthcoming working paper which showed that adding the idea of a “Hubbert peak” to energy production greatly improved the ability of a model to forecast oil prices. Based on an expected 0.9% annual increase in production over the next decade, the model predicts that real oil prices will nearly double over the same period.

The economic damage caused by such a rise is predicted to be modest, perhaps 0.2% of global GDP a year. In the past changes in oil prices have had a limited long-term impact, since any losses to oil importers are matched by gains by oil exporters. To the extent that high oil prices played a role in the recessions of the early 1980s and 2008-09, the main reason is that oil-producing countries tend to have a lower marginal propensity to consume their income, denting global demand.

Nevertheless, Mr Kumhof worries that if oil prices are high enough, the economic impact might increase substantially. On the most extreme assumptions, it could be 2% a year.

Even if the world can find more oil—in the Arctic or tar sands, say—the longer-term question is whether the era of “cheap energy” is over and how the world can adjust if it is. Developed economies are built on easy access to cheap energy, importing goods that are transported from around the world, with consumers driving many miles to work in air-conditioned offices and then flying off to sunny climes for their annual holidays. Persistently high oil prices would clearly lead to substitution (electric cars, natural-gas-powered trucks) but the transition costs could be significant.

Furthermore some potential substitutes for, or new sources of, oil (such as biofuels and tar sands) are a lot less efficient, in the sense that they require significant amounts of energy simply to produce. To the extent that this equation (energy return on energy invested, or EROI) is deteriorating, that must surely have an effect on economic growth.

“What is the minimum EROI that a modern industrial society must have for its energy system for that society to survive?” ask Carey King and Charles Hall in a recent paper*. The academics' answer: “Complex societies need a high EROI built on a large primary energy base.”

This issue is not much considered by mainstream economists, who are too busy focusing on monetary policy, the impact of fiscal austerity or the need for labour-market reforms. But just as the industrial revolution was built on coal, the post-second-world-war economy was built on cheap oil. There will surely be a significant impact if it has gone for good.

“Relating Financial and Energy Return on Investment”, October 2011.

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