The landscape of Jackson Hole, Wyoming, where central bankers gathered at their annual conference last week, is spectacular and forbidding. Jagged peaks and vast empty spaces stretch across the horizon. For the attendees, however, it was both a vista and a metaphor. Having lived through a precipitous global economic drop, they now must forecast how steep or flat will be the incline of recovery.

Ben Bernanke, chairman of the Federal Reserve, painted a sober but reassuring picture of US prospects. The basis for sustained recovery is in place, and canny Fed officials are now alive to the dangers of both deflation and inflation. Similarly Jean Claude Trichet, head of the European Central Bank, spoke about how the dust had begun to settle on the crisis. Policymakers and financial markets seem to be looking at what comes next.

Such optimism, however, may be premature. We have analysed data on numerous severe economic dislocations over the past three-quarters of a century; a record of misfortune including 15 severe post-second world war crises, the Great Depression and the 1973-74 oil shock. The result is a bracing warning that the future is likely to bring only hard choices.