Large iceberg breaks free from Antarctica

Satellite image of the 345 square mile iceberg B-20

WASHINGTON (CNN) - An iceberg 10 times the size of Manhattan Island has broken free from Antarctica's Ross Ice Shelf, The National Ice Center reported Friday.

Iceberg B-20, as it is identified by the ice center, was discovered Wednesday by satellite monitoring. The exact date the 345-square-mile berg broke off the ice shelf could not be determined because of cloudiness in the area but it is thought to have been between Sept. 20 and 26.

The 30-mile-long, 11.5-mile-wide iceberg is in the Ross Sea, south of the Pacific Ocean.

The Ross Ice Shelf, on the part of Antarctica closest to Australia and New Zealand, is one of two massive ice fields on the continent that have been the site of increased "calving" of huge icebergs. While Iceberg B-20 is large, it is dwarfed by others that have separated from the Ross and Ronne Ice Shelves in recent years.

Many scientists have speculated that the increase in the separation of ice from the Antarctic continent is caused by human-induced global warming, but few claim firm scientific evidence to support that.

Whatever the cause, the introduction of land-based ice from Antarctica into ocean waters could have some impact on sea levels.

Marine safety experts warn that an increase in icebergs off Antarctica, in the North Atlantic and along cold-water shorelines like Alaska's Prince William Sound could raise the risk of ships colliding with icebergs.

None of the Antarctic icebergs are currently in the path of heavily used shipping lanes.

The Associated Press contributed to this report.

For more NATURE news, myCNN.com will bring you news from the areas and subjects you select.

See related sites about NATURE

Note: Pages will open in a new browser window

External sites are not endorsed by CNN Interactive.