Bloomberg: A 19-square-mile (50 kilometers) ice shelf attached to an island in Canada’s northern arctic for thousands of years has broken from land, another sign of the effect of global warming, scientists said. Nearly the size of Manhattan, the 4,500-year-old Markham Ice Shelf separated from Ellesmere Island in early August and is now floating in the Arctic Ocean, said Luke Copeland, director of the Laboratory for Cryospheric Research at the University of Ottawa. Copeland and …