Icebergs dead ahead!

Mariners concerned about peril
of floating Connecticut-size masses

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WASHINGTON (CNN) -- Three enormous icebergs with the combined size of Connecticut have broken away from Antarctica's Ronne Ice Shelf and are floating free.

Mariners are concerned that these enormous bergs could break up and drift northward into the foggy waters of the South Atlantic Ocean, creating navigation hazards.

Observers at the National Ice Center say they believe the roughly rectangular icebergs broke loose sometime between May 4 and 6.

The Ronne Shelf is in the Weddell Sea, which is in the portion of Antarctica nearest to the continent of South America.

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During the past several years, there has been an unusually rapid calving, or detaching, of icebergs from the Ronne Ice Shelf and the Ross Ice Shelf, which is in the area of Antarctica closest to New Zealand. Some scientists say the increased activity could be an early sign of global warming.

The center, which is operated jointly by the U.S. Navy, Coast Guard and National Oceanic and Atmospheric Administration, gave the bergs alphanumeric identification numbers.

The largest iceberg, A-43A, measures 107 miles by 21 miles (211 kilometers by 33 kilometers); A-43B is 53 miles by 23 miles (85 kilometers by 37 kilometers); and A-44 is 41 miles by 20 miles (65 kilometers by 32 kilometers).

The National Ice Center documents a berg's point of origin and assigns it a number at its first sighting. The number is based on the quadrants into which Antarctica is divided. For example, A-44 is the 44th iceberg that the ice center has found in quadrant A, which is the area due south of South America.

Despite their size, the three icebergs will not contribute to the anticipated sea level rise associated with most predictions of global warming. Only land-bound ice, adding its volume to ocean waters, would contribute to the 1- to 3-foot rise in sea levels that climate scientists predict for the coming century.