Massive Iceberg Breaks Free In Antarctic Iceberg Floats Into Ross Sea

MADISON, Updated 5:09 p.m. EST March 22, 2000 -- A massive iceberg, perhaps the largest on record, is about to break free from an ice shelf in the Antarctic.

The iceberg is estimated to be 11,000 square kilometers in size, about twice the size of Delaware or Connecticut. Scientists at the University of Wisconsin-Madison's Antarctic Meteorological Research Center said that the the iceberg is about 295 kilometers in length and 37 kilometers wide.

A polar-orbiting satellite is currently capturing pictures (above) of the iceberg as it peels away from the Ross Marine Ice Shelf. The iceberg will soon be adrift in the Ross Sea.

"This is a very big iceberg, close to a record, if not a new record," UW scientist Matthew Lazzara said. "It's not often that you see them of this magnitude."

The National Oceanic and Atmospheric Administration's satellite is capturing the pictures. Their satellites orbit the Earth from pole to pole at an altitude of about 700 kilometers.

http://www.koin.com/sh/news/stories/nat-news-20000322-215712.html

-- Martin Thompson (mthom1927@aol.com), March 22, 2000

Answers

Super southern iceberg signals alarm on polar melting

By ANDREW DARBY HOBART Friday 24 March 2000

A super iceberg, perhaps the biggest recorded in the satellite era, is breaking off Antarctica's Ross Ice Shelf, drawing attention to concerns about the polar ice melt.

The iceberg is about 295 kilometres long and 37 kilometres wide. It would stretch roughly from Melbourne to Albury-Wodonga.

It was first reported by scientists from the University of Wisconsin yesterday after they checked satellite images showing deep fissures between the iceberg and the Ross Ice Shelf.

"This is a very big iceberg, close to a record, if not a new record," said Mr Matthew Lazzara, a scientist at Wisconsin's Antarctic Meteorological Centre.

Australian glaciologist Dr Neal Young calculated that the iceberg could cover an area of around 10,000 square kilometres and hold roughly 2000 cubic kilometres of water. Its mass was equal to about 80 per cent of Antarctica's annual snowfall.

Dr Young says this figure is important because the balance between polar snowfall and iceberg loss is keenly watched by scientists monitoring global climate change.

In recent years close attention has been paid to a series of big break-offs on the Ross Ice Shelf as scientists try to gauge the effect of global warming on Antarctica.

The first iceberg to capture wide public interest was code-named B-9. It was about 5000 square kilometres and its separation from the Ross Ice Shelf in 1987 eliminated the Bay of Whales, where early US scientific bases were established by Admiral Richard Byrd in 1928.

In 1992, a larger iceberg, B-10, broke off the same shelf. The remains of B-10 provoked a rare warning to ships off the far southern tip of South America only last October after it had drifted around the continent on a seven-year journey.

The vast scale of the Ross Ice Shelf meant that these break-offs amounted to only a small fraction of its area. But in 1998, iceberg A- 38, with an area of about 7000 square kilometres, separated from Antarctica's second-largest ice shelf, fronting the Weddell Sea.

This was much closer to the Antarctic Peninsula, where in recent years British scientists have counted at least seven smaller ice shelves breaking up as a result of local climate warming.

"Are we in a period of unusual calving of many large icebergs?" said Dr Young. "We could be tempted to say yes. But calving events also appear to be episodic. We have no records of them over a long time span."

The separated icebergs would not raise the sea level, because the ice shelf was already floating and displacing its own weight. Dr Young said of possible greater concern was the effect of the break-offs on the ice that covered Antarctica. "People believe the ice shelves act in some way to buttress the flow out," he said. "If you take them away, what's going to happen to the flow rate?"

The largest reported iceberg was sighted in 1956 and covered an estimated 31,000 square kilometres.

http://www.theage.com.au/news/20000324/A26415-2000Mar23.html

-- Martin Thompson (mthom1927@aol.com), March 23, 2000.