Central bankers are racing to shield their economies from fiscal tightening and lopsided currency swings that threaten a new global recession.

In the 72 hours after a Group of Seven conference call on Aug. 7, the Federal Reserve pledged to keep interest rates near zero through at least mid-2013, the European Central Bank intervened in bond markets and the Bank of England indicated it's ready to add more stimulus if needed. Japan signaled renewed concern about the yen and Switzerland yesterday stepped up its fight to curb an "overvalued" franc.

"Central bankers have so far been the tower of strength," said Stefan Schneider, chief international economist at Deutsche Bank AG in Frankfurt. "Lawmakers have done everything to destroy belief in their ability to solve the problems they're facing."