A Crack in an Antarctic Ice Shelf Grew 17 Miles in the Last Two Months

Feb 14, 2017

By Jugal K. Patel

A rapidly advancing crack in Antarctica’s fourth-largest ice shelf has scientists concerned that it is getting close to a full break. The rift has accelerated this year in an area already vulnerable to warming temperatures. Since December, the crack has grown by the length of about five football fields each day.

The crack in Larsen C now reaches over 100 miles in length, and some parts of it are as wide as two miles. The tip of the rift is currently only about 20 miles from reaching the other end of the ice shelf.

Once the crack reaches all the way across the ice shelf, the break will create one of the largest icebergs ever recorded, according to Project Midas, a research team that has been monitoring the rift since 2014. Because of the amount of stress the crack is placing on the remaining 20 miles of the shelf, the team expects the break soon.

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3 comments on “A Crack in an Antarctic Ice Shelf Grew 17 Miles in the Last Two Months

  • @OP – Ice shelves, which form through runoff from glaciers, float in water and provide structural support to the glaciers that rest on land.
    When an ice shelf collapses, the glaciers behind it can accelerate toward the ocean.
    Higher temperatures in the region are also helping to further the ice shelf’s retreat.

    Because the ice shelf floats and displaces its own weight of water, its melting will not in itself raise sea levels.

    However, when the ice it is holding back on the sloping land and the glaciers behind it, slide into the ocean, that will raise sea levels!

    It will also give the warmed salty ocean currents access to more Antarctic ice to warm and melt, while the melting ice-shelf drifts north towards the tropics.



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  • There is now a video of this from an over-flying aircraft which was monitoring the instruments tracking this:-

    http://www.bbc.co.uk/news/science-environment-39055524

    Plane flies along Antarctica’s giant Larsen crack

    The British Antarctic Survey (BAS) has released new footage of the ice crack that promises to produce a giant berg.

    The 175km-long fissure runs through the Larsen C Ice Shelf on the eastern side of the Antarctic Peninsula.

    If it propagates just 20km more, a block of ice a quarter the size of Wales will break away into the Weddell Sea.

    Scientists gathered the new video while recovering instrumentation that had been placed on the ice shelf.

    Uncertainty about the stability of the region means researchers cannot set up camp as they would normally do, and instead make short visits in a Twin Otter plane.

    The most recent sortie enabled the researchers also to fly along the length of the crack, which is 400-500m wide in places, to assess its status.

    No-one can say for sure when the iceberg will calve, but it could happen anytime.

    At 5,000 sq km, it would be one of the biggest ever recorded.

    When it splits, interest will centre on how the breakage will affect the remaining shelf structure.

    The Larsen B Ice Shelf further to the north famously shattered following a similar large calving event in 2002.

    The issue is important because floating ice shelves ordinarily act as a buttress to the glaciers flowing off the land behind them.

    In the case of Larsen B, those glaciers subsequently sped up in the absence of the shelf. And it is the land ice – not the floating ice in a shelf – that adds to sea level rise.

    If Larsen C were to go the same way it would continue a trend across the Antarctic Peninsula.

    In recent decades, a dozen major ice shelves have disintegrated, significantly retreated or lost substantial volume – including Prince Gustav Channel, Larsen Inlet, Larsen A, Larsen B, Wordie, Muller, Jones Channel, and Wilkins.

    Dr Paul Holland from BAS commented: “Iceberg calving is a normal part of the glacier life cycle, and there is every chance that Larsen C will remain stable and this ice will regrow.

    “However, it is also possible that this iceberg calving will leave Larsen C in an unstable configuration. If that happens, further iceberg calving could cause a retreat of Larsen C.

    “We won’t be able to tell whether Larsen C is unstable until the iceberg has calved and we are able to understand the behaviour of the remaining ice.”

    The big bergs that break away from Antarctica are monitored from space.

    They will often drift out into the Southern Ocean where they can become a hazard to shipping.

    The biggest iceberg recorded in the satellite era was an object called B-15.

    Covering an area of some 11,000 sq km, it came away from the Ross Ice Shelf in 2000.

    Six years later fragments of the super-berg passed by New Zealand.



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  • @#2 – The big bergs that break away from Antarctica are monitored from space.

    They will often drift out into the Southern Ocean where they can become a hazard to shipping.

    Of course Trump could cut NASA’s space monitoring of this glacial and oceanographic climate science, but then the shipping companies and their insurers, endangered by uncharted icebergs would object!

    Other countries’ space agencies, would in all likelihood, continue satellite monitoring, regardless of Trumpery pseudo-science!



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