The world economy has been walloped twice in the past four years by the prices of oil. In 2008, the cost of a barrel of oil had soared to $147 a barrel, weakening global growth even before the financial crisis killed it. Last year, the insurmountable crisis from the MENA region sent the prices to $127 a barrel, enough to stall the American recovery. With oil now back above $100 a barrel, and tensions with Iran running high, the worries are back. Will oil up rise, once again, disrupt the global economy?

For the moment at least, the answer is no. The cost of crude oil is back where it caused trouble in the past. But global growth is affected less by the level of the oil price than the rate of its rise. And so far that rise has been modest. A barrel of crude oil costs some 15% more than it did at the beginning of the year. However, in the first three months of 2011, the crude oil prices had surged by almost 35%.

Nor is this increase entirely a result of actual or feared problems with supply. Oil supply disruptions have indeed pushed up the prices. Rich-country oil stocks are at a five-year low and Saudi Arabia, the only OPEC producer with significant spare capacity is already pumping at a near-record rate. But part of the recent rise is demand-related. The world economy looks less fragile than it did at the beginning of the year as the odds of an imminent euro catastrophe have diminished and America’s recovery looks to be on stronger ground.

Although America’s strengthening recovery is better able to weather higher fuel costs, election-year politics is bound to bring pressure to ‘act’ against higher petrol prices. One misguided response would be a temporary cut in the petrol tax in an economy that already taxes fuel too lightly. A more dangerous idea would be prematurely to release supplies from the country’s strategic oil reserves to dampen prices. Obama did that last summer; the President will be tempted to do so again if petrol prices rise much further. At a time when there is a risk of a genuinely big supplies disruption, from Iran, that would be reckless. The odds of averting 2012 oil up rise depend disproportionately on America keeping its cool, both at home and abroad.