The Heat Is Online

Warming Waters Trigger Massive Iceshelf Rupture


(Oct. 22, 1998)

WASHINGTON - An iceberg larger than the state of Delaware has broken off the Ronne Ice Shelf in Antarctica in what scientists believe may be a sign of global warming, the U.S. National Ice Center announced today.

The iceberg, named A-38, measures 92 miles long (147 km) and 30 miles (50 km) wide and covers an area of about 2,751 square miles. The Ronne Ice Shelf is the second largest in Antarctica, located in the southern Weddell Sea.

The last time an iceberg of this magnitude broke off a Southern Hemisphere Ice Shelf was B-9 in the Ross Sea in October 1987.

Mary Keller, a scientist at the National Ice Center, sighted the iceberg using satellite data gathered by the Commerce Department's National Oceanic and Atmospheric Administration (NOAA).

The National Ice Center is run by the U.S. Navy, NOAA, and the U.S. Coast Guard, which is part of the Transportation Department. Its mission is to provide worldwide operational ice analyses for the United States and allied nations.

Ice shelves are massive, floating sheets of snow and frozen water that encircle the Antarctic mainland. Scientists believe that the breaking off, or calving, of icebergs is an important mechanism in the disintegration of ice shelves, and may be an indicator of global warming.

A team of British, Dutch and American scientists from University College London reported on Thursday that most of the ice stored in Antarctica was very stable and it did not appear to be contributing to rising sea levels.

"The icy continent now looks an unlikely source of rising global sea level this century, making thermal expansion of the ocean due to global warming, and the shrinking of mountain glaciers, more likely causes," Professor Duncan Wingham, leader of the scientific research team, said.

He said the world's oceans were rising at such a rate that millions of homes near sea level could be underwater in two centuries if current predictions were correct.

The scientists from University College are planning to study ice core samples from the Ronne Ice Shelf to learn more about it and why the iceberg broke off.