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Wednesday, October 20, 1999 Published at 14:14 GMT 15:14 UK


Sci/Tech

Falklands on alert for giant berg

B10A viewed from space

By BBC News Online Science Editor Dr David Whitehouse

The giant iceberg B10A which has been floating free off Antarctica since 1992 could approach the Falkland Islands next month.

The berg is described as "awesome" by those who have seen it from the air. It extends 90m (300 ft) above the water and as much as 300m (1,000 ft) below the ocean's surface. As it drifts into warmer waters, the iceberg has lost a lot of its bulk. In 1995, it was 110 by 50 km (68 by 31 miles) in size. Today, it is just 77 by 38 kilometres in size.


[ image: Those who have flown over the berg say it is 'awesome']
Those who have flown over the berg say it is 'awesome'
Made of freshwater ice that originally fell as snow on Antarctica, the berg took hundreds of thousands of years to form.

It broke free from the end of Thwaites glacier in Antarctica eight years ago. Driven by the tides and currents, it then broke in two. The smaller section drifted back towards the Antarctic ice pack where it poses no danger. The larger section is a different matter.

If it keeps up its present rate of progress, it will approach the Falklands next month. Scientists say that the main mass of the iceberg is not much of a threat in its present state - mariners have put a safety exclusion zone around it - but the smaller pieces that break off could be a problem.

Earlier this year, scientists lost track of B10A. "Even though a ship was dispatched to the iceberg's last known position, we were unable to find it until we started receiving data from the SeaWinds satellite in July," said Dr David Long of Brigham Young University in Utah.

Two large crevasses

Scientists were surprised by its location and its direction heading northeast between Tierra del Fuego at the southern tip of South America and the Antarctic peninsula.

The Landsat 7 satellite took an image of the berg on 20 August and showed B10A to be drifting off the southern coast of Argentina at a speed of about 12 kilometres a day.


[ image: B10A has shrunk in size over the years]
B10A has shrunk in size over the years
In September, the Royal Air Force flew a Hercules C130, along with a supporting VC10 tanker aircraft, from the Falklands to observe the iceberg.

The crew saw two large crevasses along the length of the iceberg as well as many places were relatively small bits were ready to detach. Earlier this month, Chile's navy was put on alert to monitor the iceberg as it entered the Drake Sea where it had the potential to pose a danger to shipping.

Scientists estimate the berg will take years to melt as it drifts towards warmer waters.

"We will be able to watch the iceberg's break-up for the first time with daily radar observations and better understand the effects of ocean winds and climate on melting polar ice," said Dr Long.

[ image: Its present course could take it to the Falklands]
Its present course could take it to the Falklands





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Internet Links


Virtual Antarctica

British Antarctic Survey

Satellite Image Map of Antarctica (USGS)

US National Ice Center

Professor David Long


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