I’m betting that Ben Bernanke, Mark Carney, Jean-Claude Trichet, Mervyn King and others of their ilk – heads of central banks in the U.S., Canada, Europe and England respectively − are having some sleepless nights these day. The global economy is sailing off into uncharted waters that are full of sea monsters and tempests, with compass readings that are no longer accurate and few comely mermaids to guide them.

This is not your tried and true old economy where everyone knew what to expect in a down cycle, followed by a steady and predictable upturn. Not since the Great Depression …