Central banks are pulling out all the stops to turn around the global economy. They’re pumping money into their economies, creating negative interest rates and buying billions of dollars in bonds. Yet experts are worried some of these strategies will not be enough to turn around the slump in the world. “Major central banks have run out of ammo,” says Ed Yardeni, chief investment strategist at Yardeni Research.

Central bankers are trying to stabilize their economies and currencies as they navigate through the volatility of the global slowdown, market meltdowns and investors pulling cash out. But many admit they don’t know what to do next. “The world is an uncertain place, and all monetary policymakers can really be sure of is that what will happen is often different from what we currently expect,” Stanley Fischer, the No. 2 at the U.S. Federal Reserve, said in a recent speech. FULL REPORT