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pottyprof

Antarctic Ice Discussion

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Not easy without reading the paper GW. Anyway......................................

 

Pine Island Glacier Antarctica may have passed tipping point

 

Glacier's retreat is now irreversible

 

13 January 2014, by Harriet Jarlett

 

Pine Island Glacier, the largest single contributor to sea-level rise in Antarctica, has started shrinking, say scientists.

 

http://planetearth.nerc.ac.uk/news/story.aspx?id=1588&cookieConsent=A

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2094.html

Edited by knocker

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http://www.the-cryosphere-discuss.net/8/273/2014/tcd-8-273-2014.htmlSo no increase in Antarctic sea ice! (well either none or the measurement was incorrect before the 07' period and we need to look again at papers using that data).If I'm reading too much into the paper then just ignore me but it does appear that the most sensible way around is no increase due to the anomalous nature of the increases over the period?

Wow! I am speechless!So It doesn't matter what we use to measure temperature,co2,ice or anything else for that matter, if the reality doesn't fit the theory then we can blame it on the algorithm, WTF!So that tourist ship must of got stuck in in some imaginary ice then.But seriously, how can anyone have a proper debate if we can't trust the data!And I'm not surprised that you look a this story with such glee, when really it should make you question our entire reliance on data that uses algorithms, I know it has with me!

Edited by Thunderman1981

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no increase due to the anomalous nature of the increases over the period?

Splendid new fantasy data trick.There's been no decrease in the Arctic either due to anomalous nature of the decreases over the period.

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This is still a 'discussion paper' so I'm sure a lot of folk will be looking into what the authors are saying and checking with the data.

 

Mistakes occur in every walk of life and it is good that folk check and rectify them when they are found?

 

No matter how exhaustive checks are we still end up with goods being recalled due to faults being found do we not?

 

I'm sure it is just the same with science and I'm sure science is no worse for the 'checking that goes on?

 

As it is this error can go either way? the team just think they have spotted a problem?

 

Of course it would end a lot of head scratching as to why we see this 'extension' against the background of warming and ice loss elsewhere? It reminds me of NASA declaring that there was no indication of warming from their sat data when really decaying orbits had not been allowed for in their calcs? if it is some 'gripe' from data transfer to a viewable format ( the 'bootstraps'?) then it can be fixed and we can all feel re-assured that science is getting better in it's measuring with every 'quirk' that gets ironed out?

 

Of course if you have an axe to grind with science as a whole, be it you are made to feel 'less' by lack of understanding as to WTF they are on about most of the time or that they are trying to deceive you for some reason or other  (classic paranoia ?) then you may not see it this way?

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Splendid new fantasy data trick.There's been no decrease in the Arctic either due to anomalous nature of the decreases over the period.

 

Just as well the increased shipping are hovercrafts then.

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Thank you for the link to the paper. I hadn't come across it and now I'm looking forward to reading it. In the past I've calculated trends from both Bootstrap and GSFC (friendly competitors) and both show very similar trends, spatially and temporally.

See: http://www.cawcr.gov.au/staff/preid/seaice/hovmoller_trends.html

When I get a spare moment I'll update those trend plots to include data up until the end of 2012.

 

Just reading the abstract from that paper made me a little concerned. The part-sentence "...rather than a physical increase in the rate of ice advance" is rather confusing. The term "ice advance" is most commonly used in discussion of sea ice seasonality, rather than long term trend. Anyway, if there is an error in the data I'm glad someone has picked it up. We need good quality data to know what is happening.

 

Is anyone on this discussion list going to the sea ice conference in March (Hobart)?

Thanks again

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Well I'm impressed with the way this consultation paper is being met with! The graphic showing the 2001 'anom' as one of the changes occurred obviously need explanation and I am sure , in time , it will be resolved?

 

I'm equally sure that if they find that its revision 2 that's at fault we will still see expansion of the winter ice pack, and greater retention over summer, and not an obliteration of the changes...... it will just be more accurate in it's representation of what is occurring on the ground?

 

The explanations for why we should see this behaviour hold good for me as long as we are not seeing 'runaway expansion' of the ice cover ( beyond the circumpolars) and we are/were approaching the point where even I was starting to wonder if we need to find 'something else' ( like an expansion in glacial 'rubble') to explain the scale of the increases over recent years ( when everywhere else is seeing heat driven changes?).

 

Talk of the same issue impacting Arctic ice measure is more of an academic exercise as the sat images of ice min clearly show a large reduction in ice cover ( far easier to 'see' than the scale of extension around Antarctica by the same method?)?

 

All in all I feel that if there is a problem then it needs fixing. I believe nobody is too concerned that it shows this or that just that what it shows is an accurate portrayal of that which is occuring?

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C'mon now sceptics. Many of ye often dismiss the temperature record because of adjustment and corrections made over time, why aren't ye dismissing the Antarctic sea ice record, eh!?

 

Anywho, the authors spotted an anomaly in how the earlier and newer bootstrap algorithms handle the sensor change in 1991, which can be seen in the chart below. Is it not scientific, even sceptical, the pose the question which algorithm is in error?

 

Posted Image

 

It does open the possibility that some of, though not all, the positive trend in Antarctic sea ice is due to an error rather than being as dramatic as it appear. 

On the other hand, the old algorithm could be wrong and any studies done with the old algorithm may need to be reassessed.

 

The paper, and the line of investigation, seem perfectly reasonable to me.

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SCIENTISTS from the University of York have helped discover a giant trench deeper than the Grand Canyon under the Antarctic ice.
 
Researchers from York worked with colleagues from Newcastle University, the University of Bristol’s glaciology centre, the British Antarctic Survey and the universities of Edinburgh and Exeter. They charted the Ellsworth Subglacial Highlands – an ancient mountain range buried beneath several kilometres of Antarctic ice – by combining data from satellites and ice-penetrating radars towed behind skidoos and on-board small aircraft. The researchers spent three seasons investigating and mapping the region in West Antarctica, uncovering a massive subglacial valley up to three kilometres deep, more than 300 kilometres long and up to 25 kilometres across.
 
“In places, the floor of this valley is more than 2000 metres below sea level. Dr David Rippin, senior lecturer in the environment department at York said: “We almost discovered this trough by accident, when ice penetrating radar surveys we were carrying out in the region revealed both ends of this enormous valley. “We didn’t have any radar data from its central portion, but when we looked at satellite imagery, we saw a clear manifestation of what lies beneath. “This trough is so vast, that even though it is buried by several kilometres of ice, we can still see its impact on the ice surface from space. â€œThe subglacial landscape shows where and how the West Antarctic Ice Sheet originated and grew. “It also provides important clues about the size and shape of the ice sheet in West Antarctica in a warmer global climate.â€
 
The mountain range and deep valley were carved millions of years ago by a small icefield similar to those of the present-day Antarctic peninsula, or those of Arctic Canada and Alaska

 

 

http://www.yorkpress.co.uk/news/10941598.York_scientists_discover_Antarctic___s____Grand_Canyon___/

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Yes, still at record highs of area and extent (for this time of the year).

Just amazing!

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Thanks Knocks!

 

This will surely lead to more concentration on the current issues with the sea ice numbers over the changes we have had. The better the information we have the better we understand how our models perform ( both hind-cast and forecast)?

 

I'm sure we will, by now, have a number of teams looking at the problems and so might expect so prelim findings by summer?

 

No matter the wailing, from the folk happy to see sea ice extent increases ,should we find the later data needs adjustment a clearer picture to what we have been seeing occur there since the early 80's is key to our better understanding what we need be aware of in our futures? Antarctica possibly holds the largest threat to humanity should we see the type of rapid changes we currently do across the northern polar region and so I believe it wise to gain as clear an understanding of the threat potential prior to finding ourselves facing the impacts?

 

To me what we are seeing in the PIG complex stand as a clear warning that we ought to expect similar over at Ross embayment. Any rapid changes in the grounding line of that ice shelf could lead to ( and has in past warmings) a rapid collapse of the grounded shelf and a rapid hike in sea levels not accounted for in any of the scenarios we are working with.

 

30 years ago East Antarctica was viewed as a 'sleeping giant' that we need not concern ourselves with for thousands of years, by the early noughties we were measuring the first signs that 'the sleeping giant was awaking', by the late noughties we knew that East Antarctica was not a stable as we had once hoped  it to be and showed the signs of the collapse of the major ice shelfs at regular intervals over the planets glacial regime.Depending on the scale ,and intensity of the warming over the coming decades we may discover that we are fast approaching another such event which will bring many feet of sea level rise over a period of decades.

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A couple of nice Nature articles (paper and letter) that are worth looking at:

- http://www.nature.com/nature/journal/v505/n7484/full/nature12945.html

- http://www.nature.com/nature/journal/v505/n7484/full/505491a.html

 

Some work suggesting a link between warming of the north and tropical Atlantic and changes in the Antarctic.

Edited by Tasboy

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Thanks Tas. I put a synopsis of one in new research yesterday. Posted Image

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Disappearing snow increases risk of collapsing ice shelves in Antarctica

 

A number of floating ice shelves in Antarctica is at risk to disappear entirely in the next 200 years, as global warming reduces their snow cover. Their collapse would enhance the discharge of ice into the oceans and increase the rate at which sea level rises. A rapid reduction of greenhouse gas emissions could save a number of these ice shelves, researchers at Utrecht University say in an article that was published 30 January in the Journal of Glaciology.

 

http://pers.uu.nl/disappearing-snow-increases-risk-of-collapsing-ice-shelves-in-antarctica

Edited by knocker

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That's a good article knocker.

But I often wonder whether there is still too much focus on the net (total) sea ice coverage (for Antarctica in particular) than in the very distinct (and statistically significant) regional changes in concentration and seasonality. This is particularly so in consumer press.

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Let's wait and see what becomes of the bootstrap issues before we start calling for such records eh? We now know there is a major problem with the counting of ice down there so before we all go scrabbling for understanding lets now make sure there is a reason for such?

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