Giant Chunk of Ice Breaks off Greenland Glacier

Yesterday, an iceberg twice the size of Manhattan broke off from Petermann Glacier, one of Greenland's largest and just the latest in a process scientists attribute to global warming. The iceberg that broke off was 46 miles square. Two years ago, the same glacier lost an area of 97 square miles. Scientists say the Greenland ice sheet itself is being reduced not just in size but also in volume. Glaciologist Ted Scambos is lead scientist at the National Snow and Ice Data Center at the University of Colorado.