Greenland's glaciers continue to break up.

• Position: Global Warming

Daily satellite images of Greenland have uncovered breakups at two of that country's largest glaciers in the last several months, report scientists from Ohio State University, Columbus. They expect that part of the Northern Hemisphere's longest floating glacier will continue to disintegrate within the next year. The researchers are using images updated daily from National Aeronautics and Space Administration satellites and time-lapse photography from cameras monitoring the margin of Greenland's glaciers.

First, an 11-square-mile piece of the Petermann Glacier in northern Greenland broke away. The loss is equal to half the size of New York City's Manhattan Island. Petermann previously dropped 33 square miles of floating ice between 2000-01. Petermann has a floating section of ice 10 miles wide and 50 miles long that covers 500 square miles.

What worries Jason Box, an associate professor of geography, and his colleagues, graduate students Russell Benson and David Decker, even more about the latest images is what appears to be a massive crack farther back from the margin of the Petermann Glacier that may signal an imminent and much larger breakup. "If the Petermann glacier breaks up back to the upstream rift, the loss would be as much as 60...