Jump to content
Snow?
Local
Radar
Cold?
IGNORED

Antarctic Ice Discussion


pottyprof

Recommended Posts

Posted
  • Location: Camborne
  • Location: Camborne

Another Antarctic ice shelf showing signs of instability

 

Developing Instability of Verdi Ice Shelf, Antarctica: Extensive Rift Formation

 

The Verdi Ice Shelf is a small ice shelf on the Beethoven Peninsula of Alexander Island on the Antarctic Peninsula. Its small size limits its global importance, but it does provide an excellent example of the rapid development of rifting that indicates potential instability. An ice shelf is a floating portion of a glacier, it buttresses glaciers that drain into it and is in turn buttressed by pinning points along the margin and within the ice shelf provided by islands and ice rises. Ice Shelf processes are well described by Davies (2014).

 

Cook and Vaughan (2010)  observed that in recent decades, seven out of twelve larger ice shelves around the Antarctic Peninsula have retreated significantly or been almost entirely lost. This is a pattern of behavior that indicates the ability of ice shelves to collapse entirely or significantly in a short period of time. A recent paper by Holland et al (2015) noted that the much larger Larsen C Ice Shelf is thinning from above and below. The thinning of an ice shelf is the essential pre-conditioning for collapse (Pelto, 2008). NASA last week also predicted the demise within five years of the remaining portion of Larsen B.

 

Holt et al (2013) outlined several key glaciological characteristics as typically preceding recent ice shelf collapses:

Edited by knocker
  • Like 1
Link to comment
Share on other sites

Posted
  • Location: swansea craig cefn parc 160 m asl
  • Location: swansea craig cefn parc 160 m asl

Antarctic sea ice smashes daily record by 400.000

 sq km antarctic-sea-ice-extent-for-day-136-fro

Edited by keithlucky
  • Like 2
Link to comment
Share on other sites

Posted
  • Location: Solihull, West Midlands. - 131 m asl
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl

I take it, M.I.A., that you dismissed all we were told about the breakup of the Larsen's and the data we were able to cull from where they once stood? I see no other way you could see things as you claim if in receipt of that knowledge?

 

GW

 

I read the reports  and yes there is a rapid deteriotion in the glacial ice, but has this been occurring prior to the last 50 years?

 

So why must it be being caused by CO2 induced warming?

.

We are living thru a period of natural warming (for the last 250 years, (I assume you agree)) , yes some warming is now  being introduced by CO2. but why oh why do you assume it is all down to CO2?. I still believe the level of our scientific knowledge is nearing about 75% for the atmosphere  (cloud and feedbacks still not understood) , 90% for land based temperatures(still imperfect weather forecasts), but only about 40% for the oceans( (is it 80%  of the earth's surface?) and why is it that your reported  forecasts for El Nino for the last 2-3 years have not proved correct?). Lets see what happens this year!

 

That the above is a realistic assessment  is shown by the inaccuracies of the Climate change models.

 

It really does look like a belief in scientists who are being paid to prove  global warming to be your total driving force. I would feel more confident if people  carried out investigations and research who were not being paid their salaries by organisations set up to prove the existence of CO2 based warming (oh yes like the IPCC?)  LOL

 

MIA

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: swansea craig cefn parc 160 m asl
  • Location: swansea craig cefn parc 160 m asl

The breakup of Larsen B has little or nothing to do with global warming.

The 3200-square-kilometre Larsen B ice shelf broke apart between January and March 2002 following a series of warm summers, and after melt ponds had formed on the ice shelf.
The abruptness of the break-up led many scientists to lay the blame squarely on climate change. “But the picture is much more complicated,â€
says Neil Glasser of Aberystwyth University in the UK.

When Glasser and Ted Scambos of the University of Colorado at Boulder – who has been tracking the increased movement of glaciers near the erstwhile Larsen B – reviewed satellite images from 1987 onwards, they saw
giant rifts and crevasses created by long-term glaciological processes
.

Edited by keithlucky
  • Like 2
Link to comment
Share on other sites

Posted
  • Location: Camborne
  • Location: Camborne

 

The breakup of Larsen B has little or nothing to do with global warming.

 

The 3200-square-kilometre Larsen B ice shelf broke apart between January and March 2002 following a series of warm summers, and after melt ponds had formed on the ice shelf. The abruptness of the break-up led many scientists to lay the blame squarely on climate change. “But the picture is much more complicated,†says Neil Glasser of Aberystwyth University in the UK.

When Glasser and Ted Scambos of the University of Colorado at Boulder – who has been tracking the increased movement of glaciers near the erstwhile Larsen B – reviewed satellite images from 1987 onwards, they saw giant rifts and crevasses created by long-term glaciological processes.

Natural rifts may have weakened Antarctic ice shelf – environment – 16 February 2008 – Control – New Scientist

Some observations on this

 

Firstly the paper by Glasser and Scambos 2008 was referenced in the summary of AP glacier dynamics posted above.

 

Secondly

 

The breakup of Larsen B has little or nothing to do with global warming.

 

This is complete misrepresentation of what the paper actually said.

 

A number of factors (atmospheric, oceanic and glaciological) combined to contribute to the rapid demise of the Larsen B ice shelf in 2002. We suggest that structural glaciological discontinuities played a large part because they rendered the ice shelf mechanically weak prior to its collapse. Failures along weakly sutured flow-unit boundaries were particularly important. Loss of ice at the shelf front may also have played a role because this process removed the strongest portions of the shelf, i.e. the most sutured and bonded portions in the inter-domain regions.

 

Then there is this

 

The abruptness of the break-up led many scientists to lay the blame squarely on climate change. “But the picture is much more complicated,

I don't know of any Antarctic glaciologists who lay the blame squarely on climate change. In fact in the summary already mentioned they conclude.

 

Thus, for all types of glaciers in the AP, climate change, oceanographic conditions, and glacier/ice shelf dynamics are complexly coupled, with climate change pretty obviously a key driving factor. However, the system has strong forcings other than climate change. Hence, prediction of glacier and ice shelf dynamics in the AP is hazardous at best, and clear attribution of recent dynamics to climate

 

Just my personal opinion but there are too many attempts at point scoring in this thread with airy fairy statements that are virtually always not supported by the available evidence.

 

Anyway the paper by Glasser and Scambos 2008 can be found here.

 

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCIQFjAA&url=http%3A%2F%2Fcadair.aber.ac.uk%2Fdspace%2Fbitstream%2Fhandle%2F2160%2F3753%2FGlasser%2Band%2BScambos%2B2008.pdf%3Fsequence%3D1&ei=SnNZVaS_M8r5Upi4gZgN&usg=AFQjCNFlvuumgVMiTNtLTzpoOLe6I7dh9w&sig2=jAvNELoTJg8ZdFl0RW71mw&bvm=bv.93564037,d.d24&cad=rja

Edited by knocker
  • Like 2
Link to comment
Share on other sites

Posted
  • Location: Newton in Bowland
  • Location: Newton in Bowland

Antarctic sea ice reaches new record maximumattachicon.gifimage.jpg

Yes that's my interpretation of Antarctic ice, it's certainly the polar ( pardon the pun ) opposite of ice conditions in the North Pole. I'm no expert on the matter but something seems amiss with this set against the proposals laid out by the IPCC, or I'm I missing something?
Link to comment
Share on other sites

Posted
  • Location: Newton in Bowland
  • Location: Newton in Bowland

Antarctica reaches record ice extentattachicon.gifimage.jpg

Thanks John, a good read. I did see some musings over the Western Antartica peninsula warming and calving of one of its ice shelves, which I thought was normal anyway more so with increase in ice overall, though the warming oceans around there could be due to changing ocean currents though again I'm not so sure.
  • Like 1
Link to comment
Share on other sites

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

As with 'my crack' , on the Roosevelt side of Ross, 'natural flow dynamics' demand that the ice split open as it cascades over features in the surface below ( like rapids/waterfalls in river channels?).

 

These features 'heal' ( pressure from behind closes up the rift) as the ice moves on from the disturbance but the remnant of that wound stays in the ice.

 

As we know from rivers water will always take the course of least resistance ( all our rivers here follow the faults born of the Caledonia erogeny and so strike at 90 degrees to one another.

 

On ice shelfs where the lower altitude leads to the warmer temps melt ponding finds out the old 'rifting' and enlarges it as it percolates through to the base of the shelf.

 

The 'rifting' may well have been perfectly 'natural' but the volume of melt exploiting those weaknesses, and the rapidity of the subsequent collapse, was unique and unexpected. No one, up to that date, had seen such rapid destruction of an ice shelf and it has driven the need to understand all the other shelfs to try and avoid future 'surprises' ( hence my crack having seismometers installed along its length in 08').

Edited by Gray-Wolf
Link to comment
Share on other sites

Posted
  • Location: Raunds, Northants
  • Weather Preferences: Warm if possible but a little snow is nice.
  • Location: Raunds, Northants

Yup had a look "Antarctica is a unique environment, and the complex interactions between ice, ocean and atmosphere have led to a unique set of circumstances that have resulted in sea ice growth. It may be explained by many factors, or most probably by a combination of several."

 

MY takeaway is this - It is getting cold out there Jim.

Link to comment
Share on other sites

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

 

 

MY takeaway is this - It is getting cold out there Jim.

 

And science says "Here we go again!" ........ last time a freshening of the surface occurred, trapping in the ocean heat below , we lost all of West Antarctica and Ross ( Ross alone is several meters of sea level rise)

 

EDIT: and as for LarsenB . The partial collapse lead to an 8 fold increase in the feed glaciers behind ( like a car going at 55mph suddenly running at 440mph!!!!) so what do you think happens to the 3 feed glaciers when Larsen B 'does one' prior to 2020?

Edited by Gray-Wolf
Link to comment
Share on other sites

Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

Yup had a look "Antarctica is a unique environment, and the complex interactions between ice, ocean and atmosphere have led to a unique set of circumstances that have resulted in sea ice growth. It may be explained by many factors, or most probably by a combination of several."

 

MY takeaway is this - It is getting cold out there Jim.

I often wonder why such comments cant apply to the NH

 

There was nothing new in the report but one important point that is missing is the mins are increasing as well, more then reported in that article.

 

Thickness and multi year ice is increasing down there.

Link to comment
Share on other sites

Posted
  • Location: Camborne
  • Location: Camborne

Sudden onset of ice loss in Antarctica detected

 

A group of scientists, led by a team from the University of Bristol, has observed a sudden increase of ice loss in a previously stable region of Antarctica. The research is published today in Science.

 

http://www.bris.ac.uk/news/2015/may/ice-loss-in-antarctica.html

Edited by knocker
  • Like 1
Link to comment
Share on other sites

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

I'd been keeping folk posted as to the migration of the warm bottom waters down the peninsula Knocks and this paper seems to help us see the near instant impacts of the arrival of the warm waters. Sadly they had reached as far as Ross ice shelf by 2012 so what are we to expect there over the coming years?

Link to comment
Share on other sites

Posted
  • Location: Bude
  • Weather Preferences: Extreme weather...heavy snow and heat waves
  • Location: Bude

I think more data is needed before the scaremongering starts

A quote from Andrew Shepherd, a professor of Earth observation at Leeds University on the new findings:

“I think the new estimates of ice loss computed from them are far too high, because the glaciers in this sector just haven’t speeded up that much. It could be that a bigger chunk of the thinning is down to snowfall fluctuations than the authors have accounted for, and so I would be cautious about the new numbers until more information is to hand,â€

  • Like 2
Link to comment
Share on other sites

  • 3 weeks later...
  • 2 weeks later...
Posted
  • Location: Camborne
  • Location: Camborne

Brief Communication: Newly developing rift in Larsen C Ice Shelf presents significant risk to stability

 

Abstract. An established rift in the Larsen C Ice Shelf, formerly constrained by a suture zone containing marine ice, grew rapidly during 2014 and is likely in the near future to generate the largest calving event since the 1980s and result in a new minimum area for the ice shelf. Here we investigate the recent development of the rift, quantify the projected calving event and, using a numerical model, assess its likely impact on ice shelf stability. We find that the ice front is at risk of becoming unstable when the anticipated calving event occurs.

 (open access)

http://www.the-cryosphere.net/9/1223/2015/tc-9-1223-2015.html

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Raunds, Northants
  • Weather Preferences: Warm if possible but a little snow is nice.
  • Location: Raunds, Northants

I do not get the point. These shelves always do and have to go through a calving event. It has happened for who knows how many millions of years but now a (so called) numerical model is anticipating that the ice front is at risk of becoming unstable?. So what? has this not happened thousands of times before?

Edited by Nick L
  • Like 3
Link to comment
Share on other sites

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

As you remove a shelf ( not a common event in the history ) then the ice behind is unleashed as we have seen all over the peninsula, Svalbard, and in Greenland. The only way to 'recover' is for the Shelf to re-form and hold back the rest of the land ice otherwise the glaciers feeding it speed up ( over ten times faster for most of them) and deposit more ice into the ocean. The ice sheet is up to 2 miles thick so across the uplands temp is kept real cold but drop that ice down to sea level ( liquid water) and you have issues.

 

EDIT: and about the 'happened before' cr@p? Was that when orbital forcings were such as to force cooling across the globe or was it in line with orbital forcings leading to warming?????

Edited by Gray-Wolf
  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

I do not get the point. 

I'm not surprised! :D

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

I do not get the point. These shelves always do and have to go through a calving event. It has happened for who knows how many millions of years but now a (so called) numerical model is anticipating that the ice front is at risk of becoming unstable?. So what? has this not happened thousands of times before?

 

Its the guardian so unfortunately to get to the facts you have two read 2/3 rds of the way down to get.

 

""""It is unclear whether the loss of ice is directly related to man-made climate change or a cyclical change in ocean currents"""

 

or if you prefer the alarmist nearer the top

 

""""said the loss of the shelves would speed the complete collapse of the west Antarctic ice sheet, which would eventually cause up to 3.5m of sea level rise""""

 

http://www.theguardian.com/environment/2015/mar/26/collapse-antarcticas-glaciers-ice-melt-sooner-than-thought-scientists-warn

  • Like 4
Link to comment
Share on other sites

Posted
  • Location: North York Moors
  • Location: North York Moors

 the 'happened before' cr@p? 

You don't believe large calving events happened before?

I thought you reckoned to study such things.

In a very blinkered way obviously.

  • Like 2
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • UK Storm and Severe Convective Forecast

    UK Severe Convective & Storm Forecast - Issued 2024-03-29 07:13:16 Valid: 29/03/2024 0600 - 30/03/2024 0600 THUNDERSTORM WATCH - FRI 29 MARCH 2024 Click here for the full forecast

    Nick F
    Nick F
    Latest weather updates from Netweather

    Difficult travel conditions as the Easter break begins

    Low Nelson is throwing wind and rain at the UK before it impacts mainland Spain at Easter. Wild condtions in the English Channel, and more rain and lightning here on Thursday. Read the full update here

    Netweather forecasts
    Netweather forecasts
    Latest weather updates from Netweather

    UK Storm and Severe Convective Forecast

    UK Severe Convective & Storm Forecast - Issued 2024-03-28 09:16:06 Valid: 28/03/2024 0800 - 29/03/2024 0600 SEVERE THUNDERSTORM WATCH - THURS 28 MARCH 2024 Click here for the full forecast

    Nick F
    Nick F
    Latest weather updates from Netweather
×
×
  • Create New...