AFP: A giant iceberg that snapped away from Greenland last week is a signal that global warming is causing the island’s continent-sized ice cap to melt faster than expected, scientists say. The 250-square-kilometre (100-square-mile) chunk, four times the size of Manhattan, broke away from the Petermann ice shelf on Greenland’s northwestern tip. The breakoff — the largest in the Arctic in half a century — points to Greenland’s worrying potential to stoke sea levels in the coming …