The world’s central bankers are meeting in Jackson Hole, Wyoming, and are congratulating themselves on saving the world and on greeting the burgeoning global recovery, as France and Japan record positive GDP growth and America records less-than-expected GDP decline.

Beware. The crisis is not over yet, not by a long shot. Call this the ‘cry of the party pooper economist’ if you wish. But it ain’t over until the fat deficit sags. Here is my argument.

GDP rises when imports fall by more than exports. And imports in America fell rapidly, giving GDP a boost. GDP rises by governments pump demand into the economy. And governments in America, Japan and Europe have been doing this desperately. America’s $1.2 trillion deficit is enormous. 

Now, it follows that when imports in one country fall, exports in other countries also decline, because world imports equal world exports. Exports were the powerful engine of global growth during the 1995-2007 boom. It is not good news that imports have fallen, because it implies that the growth engine, exports, also is sputtering. 

Nor is it good news that government demand has injected metamphetamine into the US and European economies. At some point, governments will need to find an ‘exit strategy’ for their fiscal stimulus plans, as government debt balloons alarmingly and as creditors refuse to lend any more. Just as metamphetamine (“speed”) addicts suffer withdrawal, so do economies when governments cut spending. And eventually they have to.

It is quite possible we will see weak sputtering recoveries that turn into new, mild recessions at the end of 2010. Companies should at least make this one of the scenarios that they seriously consider.

So, congratulations,  Ben Bernanke. You’ve managed to persuade your President, Barak Obama, to reappoint you as FOMC Chair. But plan on at least another year or two of long worried nights in your office on “H” St. in Washington. Your plans to play your saxophone again may have to be deferred.