Observer: The Arctic’s sea covering has shrunk so much that the Northwest Passage, the fabled sea route that connects Europe and Asia, has opened up for the first time since records began. The discovery, revealed through satellite images provided by the European Space Agency (Esa), shows how bad the consequences of global warming are becoming in northerly latitudes. This summer there was a reduction of a million square kilometres in the Arctic’s ice covering compared with 2006, scientists have …