Science

nitpicker

(7,153 posts) Sat Sep 23, 2017, 05:24 AM Sep 2017

Big Antarctic iceberg edges out to sea

http://www.bbc.com/news/science-environment-41366504

Big Antarctic iceberg edges out to sea

By Jonathan Amos
BBC Science Correspondent

22 September 2017

From the section Science & Environment

The giant berg A-68 looks finally to be on the move. Recent weeks have seen it shuffle back and forth next to the Antarctic ice shelf from which it broke away. But the latest satellite imagery now indicates the near-6,000 sq km block is swinging out into the Weddell Sea. A wide stretch of clear water has opened up between the berg's southern end and the remaining Larsen shelf structure, suggesting A-68 is set to swing around and head north. This is the direction the Weddell currents should take the iceberg.

Polar experts expect the trillion-tonne block to essentially bump along the shelf edge until it reaches the great eastward movement of ocean water known as the Antarctic Circumpolar Current. This would then export what is one of the largest bergs ever recorded out into the South Atlantic.

How far A-68 actually gets along this predicted path is anyone's guess, however. The berg already shows evidence of fragmentation at its edges. These bits - they carry the designation A-68b, A-68c, etc - all still float close to their parent. But in time they will get separated, and it is entirely possible that big segments with deep keels could get anchored in shallow waters and become semi-permanent "ice islands". A-68 calved during mid-winter and it required radar satellites - such as Europe's Sentinel-1 spacecraft - with their unique ability to pierce cloud and darkness to keep track of developments. With the return now to longer days in the Antarctic, opportunities are increasingly opening up for high-resolution optical satellites to take a close look at the state of the berg.
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