A vast ice shelf hanging on by a thin strip looks to be the next chunk to break off from the Antarctic Peninsula, the latest sign of global warming's impact on Earth's southernmost continent. Scientists are shocked by the rapid change of events. Glaciologist Ted Scambos of the University of Colorado was monitoring satellite images of the Wilkins Ice Shelf and spotted a huge iceberg measuring 25 miles by 1.5 miles (41 kilometers by 2.5 kilometers - about 10 times the area of Manhattan) that appeared to have broken away from the shelf. Scambos alerted colleagues at the British Antarctic...