As Bernanke put it this week, the central banks can control the availability of credit in the financial system as a stimulus to pushing on moderate economic growth. Without the easy money, the rate of growth would decline. So, with fiscal policy restricted in terms of a massive stimulus to economic activity, it has fallen on the Fed and the ECB and the BOE and the PBOC to protect the global economy against a return to deflation, recession and widespread austerity.