An area of an Antarctic ice shelf almost the size of New York City has broken into icebergs this month after the collapse of an ice bridge widely blamed on global warming, a scientist said Tuesday. "The northern ice front of the Wilkins Ice Shelf has become unstable and the first icebergs have been released," Angelika Humbert, glaciologist at the University of Muenster in Germany, said of European Space Agency satellite images of the shelf. More on Climate Change