At the very least, the chaos following the collapse of the euro will mean a second dip to the US recession. The loss of the European export market, and the likely surge in the dollar that will result from a worldwide flight to safety, would be enough to turn a weak positive growth number into a negative.
However, it is also likely that the financial panic following the collapse of the euro will lead to the same sort of financial freeze-up that we saw following the collapse of Lehman Brothers. In this case, we won’t be seeing unemployment just edge up by a percentage point or two, we will be seeing unemployment possibly rising into a 14-15 per cent range. This would be a really serious disaster.
Fortunately, the Fed has the tools needed to prevent this sort of meltdown. It can simply take the steps that the ECB has failed to do. First, and most importantly, it has to guarantee the sovereign debt of eurozone countries. The Fed simply has to commit to keep the interest rate yields on debt from rising above levels where it risks creating a self-perpetuating spiral of higher debt leading to higher interest rates, which in turn raises the deficit and debt.