Guardian: Climate change activists have chained themselves together on the northern runway at Heathrow, with the airport warning of some delays and cancellations for passengers. Thirteen demonstrators from direct action group Plane Stupid cut through a perimeter fence and entered the northern runway at 3.30am on Monday. Activists wore armlocks and lay on the runway, where police brought heavy machinery to cut them free. Plane Stupid said the protesters one of whom was dressed as a polar bear were campaigning...