Major calving event in the Antarctic

Sentinel-2 image

Image: Copernicus/Sentinel 2/Leeds Uni/Anna Hogg

On the 27th February, the BBC reported a major calving event on the Brunt Ice Shelf in the Antarctic, close to the UK’s Halley research station.

The BBC article says:

Surface instruments on the Brunt Ice Shelf confirmed the split early on Friday.

There is currently no-one in the base, so there is no risk to human life.

The British Antarctic Survey has been operating Halley in a reduced role since 2017 because of the imminent prospect of a calving.

The berg has been measured to cover 1,270 sq km – nearly 490 square miles. Halley is positioned just over 20km from the line of rupture.

BAS has an array of GPS devices on the Brunt. These relay information about ice movements back to the agency’s HQ in Cambridge.

Halley station

The British Halley research station. Image: BAS/Thomas Barningham

Scientists will be inspecting satellite imagery as it becomes available.

They will want to see that no unexpected instabilities emerge in the remaining ice shelf platform that holds Halley.

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Prof Adrian Luckman has been tracking satellite images of the Brunt in recent weeks and predicted the calving.

“Although the breaking off of large parts of Antarctic ice shelves is an entirely normal part of how they work, large calving events such as the one detected at the Brunt Ice Shelf on Friday remain quite rare and exciting,” the Swansea University remote-sensing expert said.

“With three long rifts actively developing on the Brunt Ice Shelf system over the last five years, we have all been anticipating that something spectacular was going to happen.

“Time will tell whether this calving will trigger more pieces to break off in the coming days and weeks. At Swansea University we study the development of ice shelf rifts because, while some lead to large calving events, others do not, and the reasons for this may explain why large ice shelves exist at all,” he told BBC News.

Brunt ice shelf
image captionA cloudless satellite view from early February shows the approximate berg area

Where exactly is this?

It is on the Brunt Ice Shelf, which is the floating protrusion of glaciers that have flowed off the land into the Weddell Sea. On a map, the Weddell Sea is that sector of Antarctica directly to the south of the Atlantic Ocean. The Brunt is on the eastern side of the sea. Like all ice shelves, it will periodically calve icebergs. The last major chunk to have come off in this area was in the early 1970s.

Was this breakaway anticipated?

Absolutely. Scientists continuously monitor any major cracks in the Brunt, and have been following the propagation of quite a few in recent years. Indeed, it was an acceleration in the movement of these fissures that actually prompted BAS to relocate Halley “upstream” in the flow of ice in 2016/17. All the major cracks converge on a location known as the McDonald Ice Rumples. This is a pinning point – a section of shallow sea floor – that the Brunt must grind past. One particular crack, called the North Rift, spread out from the rumples to draw the outline of the berg that has now calved.

Interestingly, the article then says this:

Is this climate change in action?

No. The calving of bergs at the forward edge of an ice shelf is a very natural behaviour. A shelf will maintain an equilibrium and the ejection of bergs is one way it balances the accumulation of mass from snowfall and the input of more ice from the feeding glaciers on land. Unlike on the Antarctic Peninsula on the other side of the Weddell Sea, scientists have not detected climate changes in the Brunt region that would significantly alter the natural process described above. What is more – estimates suggest the Brunt was at its biggest extent in at least 100 years before the calving. The event was overdue.

This is a breath of fresh air to see factual reporting rather than fearmongering.

The full article can be seen here: www.bbc.co.uk

About the author: Andy Rowlands is a British Principia Scientific International researcher, writer and editor who co-edited the new climate science book, ‘The Sky Dragon Slayers: Victory Lap

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Comments (13)

  • Avatar

    Jerry Krause

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    Hi Andy and PSI Readers,

    What natural phenomenon might cause ‘icebergs’ regularly to split off of a floating Ice Shelf???

    Have a good day, Jerry

    Reply

  • Avatar

    Davlars

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    “This is a breath of fresh air to see factual reporting rather than fearmongering.“

    Not quite..
    I posted this on Saturday morning …. https://biasedbbc.org/blog/2021/02/27/weekend-thread-27th-february-2021/

    ‘ davylars FEBRUARY 27, 2021 AT 11:23 AM
    The iceberg.
    An iceberg the size of London has detached itself from the Amery Ice Shelf in Antarctica.
    BBC breakfast interviews scientist. Who twice says it is natural and nothing to do with climate change as there is no increase in water temperature at this area of the continent.
    However they still managed to winkle it out of her that perhaps, it may be so it needs investigation.,

    Reply

    • Avatar

      MattH

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      Many environmental researchers have to practice at least one “half truth” to support funding applications for the immediate future.
      The article suggests there is no change in sea temperatures. Summer and winter are the same? And in a La Nina year?

      Reply

    • Avatar

      Andrew Rowlands

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      I can’t comment on what you saw, I can only comment on the article, and the article clearly states the calving is not due to climate change.

      Reply

      • Avatar

        Jerry Krause

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        Hi Andrew,

        You have stated your problem. You wrote many words because the authors of a science article stated “the calving is not due to climate change.” I read their article and could not find a proposed cause to what the calving was caused by. The reason they give for their statement seemed to be it ( calving) has occurred before many times through out known history.

        I simply asked a question, which MattH attempted to and did answer, to my satisfaction. His answers were simple and somewhat obvious.

        Galileo is said to have stated as translated by someone: “All truths are easy to understand once they are discovered; the point is to discover them.” I cannot review this quote without stating that SCIENCE (OBSERVATION) can only prove that which is not the truth. And pointing out the historical fact that Galileo refused to accept Tycho Brahe’s astronomical carful measurements and Johannes Kepler’s analysis of Brahe’s data which showed that the planet orbits were approximate eclipses and clearly not perfect circles.

        But never-the-less Galileo taught scientists to observe (measure) and we can learn from his error.

        Have a good day, Jerry

        Reply

      • Avatar

        Davlars

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        Exactly Andrew.
        This was shown on prime morning TV.
        You could see how disappointed the BBC reporter was when told that climate change had nothing to do with it.
        I am pretty sure the producers were screaming into the reporters earpiece, ‘Mention climate change’ so they did, and the scientists was almost bullied into saying it may need to be further investigated.
        The BBC are a vile organisation.

        Reply

  • Avatar

    MattH

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    Peak of Southern Summer warmer ocean and atmospheric cycle.

    Approximate 28 day tidal rise and fall peak, more stress to ice shelf than COVID.

    Southern storms generating ground swells stressing upwards and downward leverage on the outside perimeter of the ice shelf. There are six permanent low pressure systems circulating North of the Antarctic continent. Some of those low pressure systems have more than one center so are therefore called “complex depressions”.

    Geothermal activity.

    Wind friction stress

    Oceanic current force.

    The cumulative effect of all these phenomena can contribute the the straw that broke the Ice Shelf’s back.

    Andy. Great to see you write about science other than COVID.

    Gerry. I deserve one point for trying.

    Reply

    • Avatar

      Jerry Krause

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      Hi MattH,

      You deserve many points because everyone of your factors recognizes that this system is a dynamic system. But you have yet to recognize the dynamic factor (phenomenon) which is not variable from time to time. (A clue)

      Have a good day, Jerry

      Reply

      • Avatar

        MattH

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        Hi Jerry.

        The Earth is a spheroid because of centrifugal force.
        Centrifugal force is casting the ice shelf away from the center.

        Give me two more points please.

        Reply

        • Avatar

          Moffin

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          An oblate spheroid is a famous shape. It is the shape of the Earth and some other planets. It is like a sphere squashed from the top so the circumference around the poles is less than the circumference around the equator. Shapes of this type are called ellipsoids.

          Oblate spheroids have rotational symmetry around an axis from pole to pole.[1]

          Many planets, including the Earth and Saturn, are oblate spheroids. The difference between a sphere and the Earth’s shape is small, only about one part in 300.

          Stars spin, and some spin very fast. The faster the spin, the flatter the oblate spheroid. The Sun rotates at 2 km per second, neutron stars have speeds of thousands of km/sec.[2]

          Reply

        • Avatar

          Jerry Krause

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          Hi MattH,

          A 100% of how many points you want. Now, that two of us have independently agreed about this critically important contiuous natural phenomenon, maybe others will stop ignoring its existence.

          We will have to wait to see if anything positive like such will happen.

          Have a good day, Jerry

          Reply

  • Avatar

    Jerry Krause

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    Hi MattH,

    Just notice that in the first photo we can see a second crevasse which hasn’t separate from what I assume is the ‘main, larger’ ice shelf. Do you consider that I might consider that gravity is one factor pulling the smaller toward the larger? Einstein is said to have stated: “The true sign of intelligence is not knowledge but imagination.” I most admit I can imagine with the best and so it seems can you.

    Have a good day, Jerry

    Reply

  • Avatar

    julian

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    Antarctica has a huge Ice cap that functions like a glacier radiating in all directions. The ice flows slowly off the land and floats as an ice shelf in several places around the perimeter. The edge of these shelves are always calving. Because of the scale they blocks that break off are large and are called tabular bergs. The process is constant. In the 1960’s a tabular berg the size of Rhode Island broke off from the eastern Weddell shelf. Other than noting the size, the event was otherwise considered completely normal.

    Reply

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