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Byron Shire
October 4, 2022

On the brink: studies showing Antarctica’s climate risks

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The melting Antarctic ice sheet. Photo CSIRO

Brought to you by Cosmos Magazine and The Echo

Several groups release research detailing previously unknown processes at play down south.

Understanding ice loss in Antarctica has been improved by a range of research into causes of ice shelves and glacier retreat on the frozen continent.

Multiple studies have recently shown that increasing ocean and atmospheric temperatures are causing important changes in the Antarctic landscape – from positive feedback processes causing ice shelves to diminish, to updating the amount of ice that has been jettisoned into the ocean.

On top of this, parts of Antarctica previously considered less susceptible to climate impacts may instead by on the edge of melting into the ocean if the world is unable to halt continued rise in average temperatures due to global warming.

When positive feedback isn’t welcome

Ice loss can occur in many ways, but one of the key drivers amid climate change is the impact of warming ocean temperatures.

Just as an ice cube will melt faster in warmer water, so too can Antarctic ice sheets and glaciers.

And while these icy masses take far longer to melt than a humble ice cube, the principle at play is still the same.

Now, new modelling published in Science Advances by the Californian Institute of Technology, US, and NASA’s Jet Propulsion Laboratory (JPL) has increased the understanding of how ocean currents can accelerate ice melt in Antarctica.

 

 

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Researchers in Professor Andy Thompson’s Caltech laboratory found the narrow Antarctic Coastal Current causes a feedback process which speeds up the melting of ice sheets.

This is because freshwater released into the current from melting ice traps warm water beneath ice shelves along the vulnerable West Antarctic peninsula.  This results in a cycle where more freshwater is released into coastal currents that repeatedly pushes more warm water below the ice.

Such a cycle could mean ice shelves melt at far greater rates than previously believed.

“If this mechanism that we’ve been studying is active in the real world, it may mean that ice shelf melt rates are 20 to 40 per cent higher than the predictions in global climate models, ” says Thompson.

Iceberg crumble results in the net loss of over 36,000 sq/km of area

From melting to ‘calving’ – ice loss can occur in many ways.

Calving – the shearing of ice from the front of glaciers – is perhaps the most spectacular way ice can be lost from polar shelves. These are made-for-television moments where huge chunks of ice split from large masses and plunge into the ocean below.

And it turns out twice as much ice has been lost through calving than has previously been estimated – with projections jumping from six to 12 trillion metric tonnes.

That’s a lot of ice.

These findings published in Nature by a team at JPL demonstrate substantial change in the Antarctic coastline over the last quarter century.

The extent of ice shelf retreat along the continent was determined by mapping elevation changes shown by data from multiple observation satellites.

It shows sizeable retreats in Ellsworth Land and Marie Byrd Land in West Antarctica and parts of Australia’s territory claim around the Totten glacier.

Lead author Dr Chad Greene says this extensive ice shedding adds further risk to increased sea level rise.

“Antarctica is crumbling at its edges,” says Greene.

“And when ice shelves dwindle and weaken, the continent’s massive glaciers tend to speed up [rate of ice loss] and increase the rate of global sea level rise.”

Limiting warming to under 2 degrees could avert decline of East Antarctic Ice Sheet

While West Antarctica is especially sensitive to climate impacts, East Antarctica – the world’s largest ice sheet which is considered the least vulnerable to melt – isn’t getting off scot free.

Researchers from Australia, the UK, US and France publishing in Nature suggest East Antarctica’s resilience might be diminished if the world shoots past a two-degree increase in average temperature.

Based on projections, keeping temperatures below two degrees might prevent melting of this ice sheet from adding to sea level rise this century. In this scenario, it would contribute less than half-a-metre of sea level rise by 2500.

If that threshold is breached, the melting of the East Antarctic Ice Sheet (EAIS) could be substantial.

“If temperatures rise above two degrees Celsius beyond 2100, sustained by high greenhouse gas emissions, then East Antarctica alone could contribute around one to three metres to rising sea levels by 2300 and around two to five metres by 2500,” says co-author Professor Nerilie Abram from the Australian National University.

“A key lesson from the past is that the EAIS is highly sensitive to even relatively modest warming scenarios. It isn’t as stable and protected as we once thought.”

“Achieving and strengthening our commitments to the Paris Agreement would not only protect the world’s largest ice sheet, but also slow the melting of other major ice sheets such as Greenland and West Antarctica, which are more vulnerable to global warming,” says Abram.

Knowledge of climate impacts on Antarctica backed in recent federal report

The Australian Government recently highlighted the danger of climate change on the world’s southernmost ecosystems in its State of the Environment report, with scientists from the Australian Antarctic Division assessing the physical and biological trends facing the region.

They found continued and unpredictable changes in the patterns of sea ice formation, as well as melting of glaciers and ice sheets due primarily to the warming of upper ocean levels and the lower atmosphere.

Dr Dirk Welsford co-authored the Antarctic assessment in the report and leads the Division’s conservation and management programs. He says Antarctica cannot afford to have the worst impacts of climate change locked in.

“The Antarctic environment is still in comparatively good condition, but the pressures on the continent and the surrounding ocean are increasing,” Dr Welsford said.

“The processes that are changing the Antarctic environment are well under way and likely to continue for at least several human lifetimes.

“While time is running out to do something, to prevent locking in the most extreme changes, I’m optimistic that when the global community comes together, like it has with the Montreal Protocol and other agreements, we can slow and even reverse these changes.”


This article was originally published on Cosmos Magazine and was written by Matthew Agius. Matthew Agius is a science writer for Cosmos Magazine.


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19 COMMENTS

  1. The Scientific Method is about disproving hypothesis. 50 years of claiming the coast would be flooded by now. I went to the ocean, it hasn’t moved, that makes me the Scientist. I disproved it.

    • Maybe from where you live on planet Mars the oceans haven’t moved.
      It all a different story on planet Earth, as communities along the NSW coast – such as Collaroy, Central Coast – will readily attest.

      Maybe you channeling ex-PM… and Chief Scientist ( sarcasm )… Tony Abbott after that infamous visit to Manly Beach and he declaring that he can’t see any rise in sea level.

      • Messing with the dunes till you get erosion does not equate to sea level rise.

        If the Climate ‘Scientists’ had been right, Collaroy would have fish swimming through the streets. How quickly you forget the outrageous claims these alarmists make. When 2032 rolls around, are you going to remember the claims the planet would not be able to sustain human life by then? That was the claim 3 years ago. It’s what was being used to traumatise and demoralise the children. You all went along with it.

        • Some of our Pacific Island sisters and brother living in Fiji, Tuvalu, Kirabati, Marshall Islands know all about the trauma of sea level rise – they are losing their homes and way of life.

          • Allegedly. That island that disappeared in Tuvalu, turned out to be a victim of the locals fishing with explosives. If I had a small island nation, I too would be seriously suffering from a need to get the UN climate change grants. My people would seriously need climate refugee status to live in wealth Australia. Let me now when one of these countries actually ceases to exist……I’ll wait.

            Mean while the Marshall Islands should be more concerned about that nuclear sarcophagus being destroyed by settling into the sand. There is sea water is already washing in and out with the tide and the US government isn’t going to do anything about it. There are real problems, but they aren’t fancy or exciting, they just need to be dealt with.

  2. There is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and suchlike natural disasters, or making them more frequent. However, there is ample evidence that CO2-mitigation measures are as damaging as they are costly.

  3. Comedian Anton is back again.
    The unprecedented National Bushfire Apocalypse 2019/20, the record breaking north east NSW Flood Catastrophe 2022, just all routine natural events, yeah.
    The UN/IPCC is vey clear on the impacts of warming atmosphere and that the costs of inaction in dealing with global warming outweighs the costs of action.

    • Joachim we have apparently a climate emergency
      What ever that means..!! Yet you have not responded as to why Mr Brandt ..your Guru who you voted for ..frequently flys in the pointy end of the plane with all the other denialists Spewing hydrocarbon’s over the countryside, oceans as well .. lecturing fellow pointy ended guests
      About Climate change Nonsense.. this Hypocrite
      Is unhinged.. this FW is on a huge salary..and would not have the Australian flag in his presence..
      Sack him ..along that Ms Thorpe..another taking the Taxpayer’s money ..yet hates the nation ..
      Deport both !

      • Hah, that’s a new level of presumption – deport someone from the mob who were here before any of us because they don’t have enough affinity with the continent! 🤣🤣🤣🤣

        Barrow, when will you learn that attacking individuals is no substitute for valid arguments that support your position. Whatever it is.

        • Hang on a minute Liz, this idea has merit. If we keep equality in it i.e. we also deport White people who don’t be White enough, sounds like a good way to solve housing, water shortages, power shortages, etc

          • I have no idea what your reasoning is here, Christian. I mentioned nothing about equality, just the irony about what appears to be suggesting that if the First Nations people don’t like how they were treated they should leave.

            It’s like telling Lydia Thorpe to go back to where she came from.

          • Since all humans come from Africa, I was thinking to repatriate them there.
            But while we are problem solving, let’s occupy Tel aviv and dump them there. Like Yahweh, I enjoy multi-layered irony.

      • Barrow, Barrow, Barrow, you never fail to disappoint with your Denierism.
        Reading to learn stuff has never been your strong suit so just carryon with your distract and divert rubbish.

        It must be nauseous for you continually going off piste, “Doing a Barrow”.

  4. It’s ‘the sound of one hand clapping itself’, Joachim. We will not ever get
    a trickle of any form of common sense out of dunderheads.

    • The sound of turbulent air flow? We have microphones and amplifiers, we know these things, and we get consistent results without having to rig or misinterpret the data.

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