Environment News Service: Protesters from the climate action group Plane Stupid this morning shut down Britain’s third largest airport by cutting through the perimeter fence and camping on the runway, surrounding themselves with fortified security fencing. The protest at Stansted Airport just north of London began at 3:15 this morning while airport’s only runway was temporarily closed for maintenance work. Plane Stupid aimed to prevent the scheduled reopening of the runway at 5 am. The group said its …