The eruption of Iceland’s Eyjafjallajökull volcano last last week shut down air traffic into and out of, and all across northern Europe. “Chicago cut off from the continent,” I thought — a strange predicament for our global city. Who was trapped here and couldn’t get home? Who was there and desperately needed to be here? What business couldn’t be conducted? What concerts would have to be canceled? Would an unheralded conductor get the chance of a lifetime to lead the CSO because a famous maestro was stuck in Berlin?