Iceberg poses no threat to Antarctic personnel

12/16/04

Annual long-range supply effort, icebreaking operations are on schedule

Arlington, Va.--National Science Foundation (NSF) officials said today that iceberg B-15A is not blocking access to McMurdo Station, the U. S. logistics hub for much of the nation's research activity in Antarctica, contradicting widely circulated reports to the contrary.

Karl Erb, Director of NSF's Office of Polar Programs said the real effect of the enormous iceberg had been to shield large parts of the Ross Sea from wind and ocean currents, with the result that sea ice had formed over a larger area than usual in the sea-lanes approaching McMurdo Sound. Before McMurdo Station can be resupplied icebreakers have to open a channel each year through which the resupply ships can proceed, and the icebreaker task will be more difficult this year. Erb expressed confidence that the U.S. Coast Guard and its crew aboard the icebreaker USCGC Polar Star will succeed. He added that NSF is currently arranging for a backup icebreaker that can assist the Polar Star if necessary. This is in response to a Coast Guard recommendation.

"There is absolutely no truth to reports circulating widely that the stations are facing a crisis when it comes to supplies of any kind, including food. Personnel at McMurdo and South Pole stations are in no danger," Erb said.

Some news media have conveyed the misimpression that an enormous iceberg, B-15A, is blocking ship access to the McMurdo Station seaport.

The U.S. research station at the geographic South Pole is more than 800 miles inland, and supplies are airlifted there from McMurdo after arriving on ships.

B-15A is a fragment of a much larger iceberg that broke away from the Ross Ice Shelf in March 2000. Scientists believe that the enormous piece of ice broke away as part of a long-term natural cycle (every 50-to-100 years, or so) in which the shelf--which is roughly the size of Texas-- sheds pieces much as human fingernails grow and break off.

The berg initially drifted toward McMurdo Sound and grounded near Cape Crozier on Ross Island. It has since broken into pieces that still are very large. Some remain in place, but the largest splinter--B-15A, approximately 100 miles long--is moving north at roughly 1-3 three kilometres per day.

The berg's fate is unclear, as it depends on unpredictable winds, tides and other forces, but possibilities include colliding with the floating Drygalski Ice Tongue or continuing north, eventually to melt. If it's the former, the impact with the ice tongue could come as soon as Dec. 24.

The U.S. Coast Guard icebreaker Polar Star left Seattle, Washington, on Nov. 4 and should reach the edge of the sea ice about Dec. 27. It will begin immediately to cut a channel in the sea ice for the supply ships.

Officials agreed that the position of B-15A presents no obstacle to navigating the ship to the ice edge and beginning its work of opening a channel through this year's roughly 80 nautical miles of sea ice. In a normal year, the icebreaker clears a channel through perhaps 10 miles of first-year ice.

In some prior years, the Coast Guard deployed both the Polar Sea and the Polar Star to open the channel but the Polar Sea is in dry dock for a major refit. NSF is negotiating to bring a chartered icebreaker to assist the Polar Star this year.

Source: Eurekalert & others

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