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Antarctic Ice Discussion


pottyprof

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Posted
  • Location: Camborne
  • Location: Camborne
On 7/12/2017 at 13:55, Gray-Wolf said:

http://www.bbc.co.uk/news/science-environment-40321674

https://www.theguardian.com/world/2017/jul/12/giant-antarctic-iceberg-breaks-free-of-larsen-c-ice-shelf

We will now find out what this means for the ice behind? Is it flawed and so will collapse? Will the feed ice speed up?

Yes indeed GW

Don’t worry about the huge Antarctic iceberg — worry about the glaciers behind it

http://www.news.com.au/technology/environment/natural-wonders/dont-worry-about-the-huge-antarctic-iceberg-worry-about-the-glaciers-behind-it/news-story/adbe0a024b862fbd2346f0e0dd1f2eb4

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Posted
  • Location: Camborne
  • Location: Camborne

Solve Antarctica’s sea-ice puzzle

John Turner and Josefino Comiso call for a coordinated push to crack the baffling rise and fall of sea ice around Antarctica.

Quote

Different stories are unfolding at the two poles of our planet. In the Arctic, more than half of the summer sea ice has disappeared since the late 1970s1. The steady decline is what global climate models predict for a warming world2. Meanwhile, in Antarctic waters, sea-ice cover has been stable, and even increasing, for decades3. Record maxima were recorded in 2012, 2013 and 2014 (ref. 4).

So it came as a surprise to scientists when on 1 March 2017, Antarctic sea-ice cover shrank to a historic low. Its extent was the smallest observed since satellite monitoring began in 1978 (see ‘Poles apart’) — at about 2 million square kilometres, or 27% below the mean annual minimum.

Researchers are struggling to understand these stark differences5. Why do Antarctica’s marked regional and seasonal patterns of sea-ice change differ from the more uniform decline seen around most of the Arctic? Why has Antarctica managed to keep its sea ice until now? Is the 2017 Antarctic decline a brief anomaly or the start of a longer-term shift6, 7? Is sea-ice cover more variable than we thought? Pressingly, why do even the most highly-rated climate models have Antarctic sea ice decreasing rather than increasing in recent decades? We need to know whether crucial interactions and feedbacks between the atmosphere, ocean and sea ice are missing from the models, and to what extent human influences are implicated6.

http://www.nature.com/news/solve-antarctica-s-sea-ice-puzzle-1.22317?WT.mc_id=TWT_NatureNews&sf99146355=1

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

We know ( or should?) that warmer sst's will eventually limit the extent that ice can grow to. Throw in some energy from storms and the peripheral ice is broken off and tossed in the warmer waters so melts. We have seen this over some Antarctic winters where a Major storm has dropped figure by over 1 million sq km. 

I believe we saw a change begin in 2014 but the late freeze season breakup of the peripheral pack 'expanded' extent/area as the fragments pushed 'open water' beyond the 15% cover so became classed as 100% ice covered. In Antarctica where the peripheries expand outward this can happen leading to a big max but then a rapid decline for the very beginning of the melt season as the fragmented ice drifts out firther or melts our in the open waters again dropping below 15% cover and so instantly 'ice free'.

The healing of the Ozone hole is also behind recent changes reversing the expansion we saw over it's life time? If we see reduced Katabatic outflow then we do not see ice pushed north and 'ice factories emerge in the polynya's caused.

It has all been a case of the worse possible timing. both the alleged 'pause' in warming and the sight of ever expanding antarctic sea ice helped the paid deniers win the debate over intervention and stronger mitigation against the worse that AGW would throw at us. We have now passed by the point of no return and so will miss our 2c target even if we ceased activities driving warm ing right now.

We will see 'variability' in sea ice cover but I believe we are past 'max Sea ice' for Antarctica and levels will rapidly drop away to those modelled earlier with areas like ross Sea seeing marked reductions in cover bringing issues of longer periods of mechanical weathering on the ice shelf beyond.

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Posted
  • Location: Camborne
  • Location: Camborne

Ocean forced variability of Totten Glacier mass loss

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A large volume of the East Antarctic Ice Sheet drains through the Totten Glacier (TG) and is thought to be a potential source of substantial global sea-level rise over the coming centuries. We show that the surface velocity and height of the floating part of the TG, which buttresses the grounded component, have varied substantially over two decades (1989–2011), with variations in surface height strongly anti-correlated with simulated basal melt rates (r = 0.70, p < 0.05). Coupled glacier–ice shelf simulations confirm that ice flow and thickness respond to both basal melting of the ice shelf and grounding on bed obstacles. We conclude the observed variability of the TG is primarily ocean-driven. Ocean warming in this region will lead to enhanced ice-sheet dynamism and loss of upstream grounded ice.

http://sp.lyellcollection.org/content/early/2017/08/22/SP461.6 (open access)

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Posted
  • Location: Camborne
  • Location: Camborne

Record-low 2016 Antarctic sea ice due to 'perfect storm' of tropical, polar conditions

Quote

The sudden, unexpected nosedive in Antarctic sea ice last year was due to a unique one-two punch from atmospheric conditions both in the tropical Pacific Ocean and around the South Pole.

https://www.sciencedaily.com/releases/2017/08/170831092650.htm

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

Another large calve just occurred from the P.I.G., lets see if it shows signs of further rapid retreat over summer as the grounding line appears to edge off the shelf it sits atop and allow inundation of the basin beyond?

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Posted
  • Location: Camborne
  • Location: Camborne

Antarctica: Return of the Weddell polynya supports Kiel climate model

After 40 years, a large ice-free area appears again in the Southern Ocean in mid-winter

Quote

Currently, winter has still a firm grip on Antarctica. At this time of the year, the Weddell Sea usually is covered with a thick layer of sea ice. In spite of the icy temperatures in the region, satellite images depict a large ice-free area in the middle of the ice cover. The area of the hole in the ice is larger than The Netherlands and it fascinates climate and polar researchers worldwide. Scientists from the GEOMAR Helmholtz Centre for Ocean Research Kiel are closely monitoring the developments. "For us this ice-free area is an important new data point which we can use to validate our climate models. Its occurrence after several decades also confirms our previous calculations," says Dr. Torge Martin, meteorologist and climate modeler in the GEOMAR Research Division "Oceans Circulation and Climate Dynamics".

https://www.eurekalert.org/pub_releases/2017-09/hcfo-aro092917.php

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Posted
  • Location: Chisinau, Moldova.
  • Location: Chisinau, Moldova.
On 01.10.2017 at 13:09, knocker said:

Antarctica: Return of the Weddell polynya supports Kiel climate model

After 40 years, a large ice-free area appears again in the Southern Ocean in mid-winter

https://www.eurekalert.org/pub_releases/2017-09/hcfo-aro092917.php

A good read and will be interesting to see how long it sticks around for and how much heat is radiated to space as a result.

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

I think it will prove to be another troubling summer for ice shelf evolution around the Antarctic continent. I will be paying attention to the ice left behind after the LarsenC calve. Will we see a similar collapse to what we witnessed with LarsenB with the constant freeze thaw of the fohn winds leading to a shelf ready for rapid collapse into tabular bergs?

I'm also a tad concerned about Ross with the major crevasses at Roosevelt island end looking much broader this spring?

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Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)

Apologies if this has already been posted somewhere, but do we currently have a convincing explanation for why the Antarctic sea ice dropped off so dramatically from record-high levels in mid-2015? What's the latest on this?

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

I think it was a combination of things that brought us the step change back to where we were in the late 70's?

The two impacts I feel that altered was the change positive of the Pacific drivers like the PDO to positive and the IPO to positive? This combined with a more rapid repair of the ozone hole meant that the conditions that were forcing ice away from Antarctica simply stopped.

So we are now back to a state where Ozone loss is not forcing stronger Katabatic winds off the continent and so lessening the migration North of sea ice and an uptick in stormy weathers around the continent smashing out peripheral ice.

Today we sit a good million below the 1980's average so we might also be seeing the impacts of 30 years of warming now crashing into the coastal regions to?

Longer 'open water around our remaining ice shelfs and stormier weathers will lead to break offs from the shelfs in a way that was not possible whilst sea ice protected the region from swells?

Sadly the pine Island/Thwaites regions are at a critical point and any further collapse up stream will take the grounding line off the underwater peaks their shelfs are sat on and into an ever deepening gorge. Recent papers again warn us of the rapid collapse we will see should their grounding lines shift as ice cliff failures lead to constant retreat inland resulting in the break up of the ice separating east and west Antarctic ( not seen for 125,000 years) and rapid sea level hikes swamping most port areas around the globe.

Edited by Gray-Wolf
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

Very worrying, Ian...though some it seems find such prospects amusing, Which is IMO almost as worrying as what's happening!:angry:

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
4 hours ago, Ed Stone said:

Very worrying, Ian...though some it seems find such prospects amusing, Which is IMO almost as worrying as what's happening!:angry:

Between what we learned from Shakhova et all this autumn and  what we are awaiting in East Antarctica from Pine Island and Thwaites I imagine its a case of fingers in the ears and a loud "La,La,La!" ?

We go out on a La Nina across the ENSO regions but a global temp year higher than those of the Super Nino Year of 98'......... I'll not mention global atmospheric circulation esp. up in the strat after last years QBO surprises suffice to say it is no wonder we are seeing the Ozone hole rapidly healing in the Antarctic Spring........ but then that's not helping Thwaites and Pine is it?

Well if trump gets his way he'll raise the regional temps of some areas of our world!

Anyhow Seasons Greetings me eld mucka!!!

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft
On ‎10‎/‎12‎/‎2017 at 21:05, Relativistic said:

Apologies if this has already been posted somewhere, but do we currently have a convincing explanation for why the Antarctic sea ice dropped off so dramatically from record-high levels in mid-2015? What's the latest on this?

All part of natural variation as were the increases

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
37 minutes ago, stewfox said:

All part of natural variation as were the increases

Sorry stew but 'No' the impacts of the human generated ozone hole are well studied and impacts documented. Take a stroll around the Nasa site and see what we have learned since the early 80's.

There are also questions over the impacts of warming on 'naturals' like PDO and IPO. The IPO negative saw some queer impacts over its life ranging from record strong burst of the Trades over the ENSO regions that lead to the record bulge of warm water out west ( the thing that fed two years of record kelvin waves pushing out prior to the 15/16 Nino setting up) but also the record levels of shear seen over the Caribbean over that period as the tropical Atlantic struggled to 'balance out' the two tropical basins ( calming 'cane's in the atlantic basin post 05').

We cannot see a Nino push global temps to 1.5c+ above the 1850's base line without expecting forced changes to the running of our atmosphere/Oceans can we?

EDIT:

index.php?action=dlattach;topic=429.0;at

Pine island is looking to calve again after the september calve ( thanks to wipneus over on ASIF)

 

Edited by Gray-Wolf
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Posted
  • Location: York
  • Weather Preferences: Long warm summer evenings. Cold frosty sunny winter days.
  • Location: York
5 minutes ago, Gray-Wolf said:

Sorry stew but 'No' the impacts of the human generated ozone hole are well studied and impacts documented. Take a stroll around the Nasa site and see what we have learned since the early 80's.

There are also questions over the impacts of warming on 'naturals' like PDO and IPO. The IPO negative saw some queer impacts over its life ranging from record strong burst of the Trades over the ENSO regions that lead to the record bulge of warm water out west ( the thing that fed two years of record kelvin waves pushing out prior to the 15/16 Nino setting up) but also the record levels of shear seen over the Caribbean over that period as the tropical Atlantic struggled to 'balance out' the two tropical basins ( calming 'cane's in the atlantic basin post 05').

We cannot see a Nino push global temps to 1.5c+ above the 1850's base line without expecting forced changes to the running of our atmosphere/Oceans can we?

EDIT:

index.php?action=dlattach;topic=429.0;at

Pine island is looking to calve again after the september calve ( thanks to wipneus over on ASIF)

 

So do you believe that solar cycles have no impact on ozone depletion or production?

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

There is the yearly cycle from the sun over the poles of course! but the mixing of the strat from the trop is also now adding issues to our 'balance as is the circulation of the strat as we saw with the failed reversal of the QBO a year ago. The troposphere is not a sealed layer and the tropopause is frequently breached by over tall thunder storms introducing moisture and ozone into the strat and then 'odd stratospheric winds redistribute this over the entire globe via the knock on  of wobbly PV's invading lower lats.

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft
34 minutes ago, Gray-Wolf said:

Sorry stew but 'No' the impacts of the human generated ozone hole are well studied and impacts documented. Take a stroll around the Nasa site and see what we have learned since the early 80's.

Pine island is looking to calve again after the september calve ( thanks to wipneus over on ASIF)

 

We have been here for trying explain away decreases increases and now decreases all due to man and not natural variation

Posting pictures from high summer of melt is not unusual. Both this and the Artic thread are quite as there is little to report. Artic free summer seems a distance memory now.

This year the IJIS Antarctica  is showing a faster then average retraction cf 3 yrs ago when it was above average (all time high oct 2014). Let’s see how the next 30 years pan out and if we have any identifiable step change

see below

There’s no indication this is anything but just natural variability,” lead study author John Turner said in a statement. “It highlights the fact that the climate of the Antarctic is incredibly variable.”

 Writing in Geophysical Research Letters last month, the scientists explain how the sea ice crash coincided with a series of remarkable weather anomalies and storms—beginning, in September, with an extreme low pressure center in the Amundsen sea off the coast of West Antarctica. In October, strong atmospheric Rossby waves brought additional heat toward the south pole, triggering ice loss in the Ross Sea and Indian Ocean. By November, the Weddell Sea was shedding 30,000 square miles of ice—roughly the area of South Carolina—each day.

 

https://gizmodo.com/this-is-why-antarctic-sea-ice-crashed-this-year-1796604475

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