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Delaware-Sized Iceberg Could Break Off of Antarctica at Any Moment

posted by n1 on Thursday July 06 2017, @09:42AM   
from the breaking-the-ice dept.

takyon writes:

A deep crack on on Antarctica's Larsen C ice shelf has nearly severed off one of the largest icebergs ever recorded:

One of the largest icebergs ever recorded — 2,500 square miles, about the size of Delaware — is about to break off Antarctica, according to the European Space Agency. The iceberg could speed up the break-off of other ice chunks, eventually eating away at a barrier that prevents ice from flowing to the sea.

The impending iceberg is being carved from one of the continent's major ice shelves, called Larsen C. Scientists have been monitoring Larsen C for months now, as a deep crack has slowly extended over the course of 120 miles. Only about three miles of ice are keeping the iceberg attached to the shelf, ESA says. No one knows when it will break off — it could be any moment — but when it does, the iceberg will likely be 620 feet thick (about the height of the Waldorf Astoria hotel in New York) and contain roughly 1 trillion tons of ice. It'll be drifting north toward South America, and could even reach the Falkland Islands. "If so it could pose a hazard for ships in Drake Passage," Anna Hogg from the University of Leeds, said in a statement.

Also at BBC.

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Original Submission

• Some more background and a video (Score: 2) by martyb on Thursday July 06 2017, @01:09PM

  by martyb (76) on Thursday July 06 2017, @01:09PM (#535697) Journal

  Found an older story on phys.org, Video: Larsen-C ice shelf crack [phys.org] (from 2017-04-21).

  It includes a video [internapcdn.net] showing the progress of the crack across the Larsen C ice shelf. Also shows how interferometry of radar images is used to better 'see' how far the crack has progressed.

  Also, there is another story on phys.org, Giant iceberg in the making [phys.org] (posted 2017-07-05) which provides a summary, in metric units, of what is happening:

  All eyes are on Antarctica's Larsen C ice shelf as a deep crack continues to cut across the ice, leaving a huge chunk clinging on. When it eventually gives way, one of the largest icebergs on record will be set adrift. Even before the inevitable happens, ESA's CryoSat mission can reveal some of the future berg's vital statistics.

  Monitored by the Copernicus Sentinel-1 radar pair, the crack in the ice is now around 200 km long, leaving just 5 km between the end of the fissure and the ocean.

  While we wait for Sentinel-1 to tell us when this 6600 sq km iceberg is spawned, CryoSat can reveal what the berg's measurements will be.

  This Earth Explorer satellite carries a radar altimeter to measure the height of the ice surface. In general, this information is used to work out how the thickness of sea ice and land ice is changing and, consequently, how the volume of Earth's ice is being affected by the climate.

  Noel Gourmelen from the University of Edinburgh said, "Using information from CryoSat, we have mapped the elevation of the ice above the ocean and worked out that the eventual iceberg will be about 190 m thick and contain about 1155 cubic kilometres of ice.

  "We have also estimated that the depth below sea level could be as much as 210 m."

  There is an animated gif [internapcdn.net] of the predicted shape of the forthcoming iceberg, too.

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