The bad smell hovering over the global economy

Attempts at economic stimulus have left a bad smell. Central banks are starting to think the unthinkable - helicopter money

All is calm. All is still. Share prices are going up. Oil prices are rising. China has stabilised. The eurozone is over the worst. After a panicky start to 2016, investors have decided that things aren't so bad after all.

Put your ear to the ground though, and it is possible to hear the blades whirring. Far away, preparations are being made for helicopter drops of money onto the global economy. With due honour to one of Humphrey Bogart's many great lines from Casablanca: "Maybe not today, maybe not tomorrow but soon."

Related: Helicopter money is closer than you think