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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.

Pine Island glacier

The work, published in Nature Climate Change, shows the glacier's retreat may have begun an irreversible process that could see the amount of water it is adding to the ocean increase five-fold.

'At the Pine Island Glacier we have seen that not only is more ice flowing from the glacier into the ocean, but it's also flowing faster across the grounding line - the boundary between the grounded ice and the floating ice. We also can see this boundary is migrating further inland,' says Dr G. Hilmar Gudmundsson from NERC's British Antarctic Survey, a researcher on the project.

The team, which included scientists from the CSC-IT Center for Science in Finland, the Chinese Academy of Sciences and the Universities of Exeter and Bristol, used three computer models as well as field observations to study how the glacier's ice flows and to simulate how this will change over the coming decades.

'Not only is more ice flowing from the glacier into the ocean, but it's also flowing faster'
- Dr Gudmundsson, BAS


All the models agreed that the Pine Island Glacier has become unstable, and will continue to retreat for tens of kilometres.

'The Pine Island Glacier shows the biggest changes in this area at the moment, but if it is unstable it may have implications for the entire West Antarctic Ice Sheet,' says Gudmundsson. 'Currently we see around two millimetres of sea level rise a year, and the Pine Island Glacier retreat could contribute an additional 3.5 - 5 millimeters in the next twenty years, so it would lead to a considerable increase from this area alone. But the potential is much larger.'

Pine Island Glacier currently contributes 25 per cent of the total ice loss from West Antarctica. If the entire West Antarctic Ice Sheet was to retreat, it could cause sea level to rise up to five metres.

'The models show a strong agreement and the result is a striking vision of the near future. All the models suggest that this recession will not stop, cannot be reversed and that more ice will be transferred into the ocean,' says Dr Gaël Durand of CNRS, Laboratoire de Glaciologie et de Géophysique de l'Environnement at the University of Grenoble, another researcher on the project.

Pine Island glacier

Pine Island glacier.

Gudmundsson doesn't believe that an iceberg the size of Manhattan, which broke off from the Pine Island Glacier last July, will have had any impact on the self-sustained retreat of the grounding line currently seen at the glacier.

'Calving, where an iceberg breaks off from a glacier, does not contribute to sea level rise as the iceberg is already in the ocean so it will have already displaced any water it was going to,' Gudmundsson explains.


This work was supported by the ice2sea project, and by NERC grant number NE/H02333X/1.

L. Favier, G. Durand, S. L. Cornford, G. H. Gudmundsson, O. Gagliardini, F. Gillet-Chaulet, T. Zwinger, A. J. Payne and A. M. Le Brocq (2013) Retreat of Pine Island Glacier controlled by marine ice-sheet instability Nature Climate Change DOI: 10.1038/NCLIMATE2094


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Your comments

I am just astounded that their concern for this glacier is so great: http://en.wikipedia.org/wiki/File:Iceseismic.jpg

4TimesAYear, USA
Monday, 13 January 2014 - 01:28

How does shrinkage of Pine Glacier square with GROWTH of antarctic ice sheet? Surely one cancels out the effects of the other?

H, earth
Monday, 13 January 2014 - 10:50

It's rather odd that this paper does not refer to earlier NERC-funded work by Jenkins et al., published as Jenkins, A., et al., 2010.
Observations beneath Pine Island Glacier in West
Antarctica and implications for its retreat. Nature
Geoscience 3:468-472, http://dx.doi.org/10.1038/
ngeo890. They wrote, "Once the grounding line began its downslope migration from the ridge crest prior to the 1970's, a period of rapid change was inevitable, and since that time oceanic variability may have had relatively little influence on the rate of retreat. Thinning of the ice shelf through increased basal melting has been sustained by a positive feedback in which thinner ice allows more ocean heat over the ridge and into the growing inner cavity. Unless some complexity in the flow of the glacier or in its interaction with the ocean acts to stabilise the grounding line, its retreat is likely to continue for another 200 km until it encounters the next rise in the bed."

Gwyn Griffiths, UK
Monday, 13 January 2014 - 11:54

We may be about 20 years away from a new Ice Age.

2016, TOLLMANN'S HYPOTHETICAL BOLIDES RETURN

VULCAN REVEALED - A Dangerous New Jovian Sized Body In Our Solar System

Barry M Warmkessel, United States
Monday, 13 January 2014 - 17:57

The headline says "Glacier's retreat is now irreversible" while the text reads "may have begun an irreversible process..."

"May" versus "Is" - the definition of Junk Science!

Stan Bartsch, Cincinnati, OH
Monday, 13 January 2014 - 19:22

Well! It is summer, there for one thing!

For another, if teh glacier is shrinking, how come THREE ICEBREAKERS got stuck in the ice there?!

They had to be abandoned by the scientists.
The very people who were there to PROVE that the ice was melting. But they got caught, instead! What a laugh!

But never fear, the poor crew of the ships were made to stay there!

Norma, NYC
Monday, 13 January 2014 - 20:51

I guess if you repeat something often enough....

PB, Australia
Monday, 13 January 2014 - 22:16

@ Gwyn Griffiths, the paper does reference a subsequent paper by many of the same authors: Jacobs et al. (2011) Stronger ocean circulation and increased melting under Pine Island Glacier ice shelf Nature Geoscience 4, 519-523 doi:10.1038/ngeo1188

Mark, Canada
Monday, 13 January 2014 - 22:29

My....all the loonies are commenting...

garee peters, nash tn
Tuesday, 14 January 2014 - 14:46

'Calving, where an iceberg breaks off from a glacier, does not contribute to sea level rise as the iceberg is already in the ocean so it will have already displaced any water it was going to,' Gudmundsson explains.

I do not necessarily agree with the above explanation.

The invert level of the glacier's bed at the land extent and the angle of entry will affect the initial displacement volume of ocean water; this may be less or greater than the volume of free floating ice. Coastal sea ice is essentially a 'cantilever structure' capable of supporting ice that is less than 80% submerged and calving would result in a rise of ocean level.

MKE, United Kingdom
Friday, 17 January 2014 - 22:16

"May" versus "Is" - the definition of Junk Science!

Stan Bartsch, Cincinnati, OH
Monday, 13 January 2014 - 19:22

Surely it is disingenuous to berate the authors of the scientific report because of an inappropriate heading penned by a journalist.

Junk Science - No! Journalistic Licence - Yes! Unfortunately too many people form their opinions based on the Reporters' and Editors' headlines and not on the quoted factual content of an article.

MKE, United Kingdom
Tuesday, 21 January 2014 - 03:27

Read the paper (which should be accessible to everyone) and you'll see there's no exaggeration here; the article accurately summarizes what the scientists say, both in the paper and in the interview we did with them.

From the paper text:
"Here we show that for the next decade the PIG grounding line is probably engaged in an irreversible retreat over tens of kilometres and that the dynamic contribution to SLR will remain at a significantly higher level compared with preretreat conditions."

All this stuff about junk science, people getting stuck in icebreakers somehow disproving the reality of climate change (!) etc is just a distraction.

Tom Marshall, Planet Earth Online
Tuesday, 21 January 2014 - 09:54

REPLY TO Tom Marshall, Planet Earth Online
Tuesday, 21 January 2014 - 09:54

The Heading to the Article dated13 January 2014, by Harriet Jarlett is 'Glacier's retreat is now irreversible'

.From the paper text:
"Here we show that for the next decade the PIG grounding line is probably engaged in an irreversible retreat...' (Your selected quote)

Stating that 'retreat is now irreversible' is not the same as ' probably engaged in an irreversible retreat'. The former is a statement of established fact and the latter a statement of probability. In scientific debate these distinctions are important. Ignoring these distinctions invites climate change sceptics to promote their dangerous and misleading agenda.
viz.
"May" versus "Is" - the definition of Junk Science!

Stan Bartsch, Cincinnati, OH
Monday, 13 January 2014 - 19:22

MKE, United Kingdom
Tuesday, 21 January 2014 - 23:24

This is how headlines work, though; they present a very simplified version of the gist of the story, and to expect them to convey all the nuances found below is unrealistic. Research papers, by contrast, tend to use very cautious language, as seen here. You'll note that one of the scientists stated that 'All the models suggest that this recession will not stop, cannot be reversed and that more ice will be transferred into the ocean.' So as I said, we maintain that the headline is basically an accurate account of the views of the scientists, although obviously it's simplified for reasons of space and accessibility.

Tom Marshall, Planet Earth Online
Wednesday, 22 January 2014 - 10:48

REPLY TO Tom Marshall, Planet Earth Online
Wednesday, 22 January 2014 - 10:48

RE: QUOTE BY Tom Marshall, Planet Earth Online
Tuesday, 21 January 2014 - 09:54
"All this stuff about junk science, people getting stuck in icebreakers somehow disproving the reality of climate change (!) etc is just a distraction."

So, why give those denying the science of Global Weather Change an excuse to create distractions.

'Glacier's retreat irreversible indicated by latest studies'
This article heading would be shorter than many, have impact, is more informative and without exaggeration.

Just trying to add constructive comment.

MKE, United Kingdom
Saturday, 25 January 2014 - 02:10

fascinating undertakings, perhaps so with academic cross comparisons with southern France, and dead sea history, concerning scrolls. Reset aspect in curiously aligned undertakings. interesting too along whole computer level, ring fenced or not aspects, etc. best wishes.

mr parker, harrow
Thursday, 30 January 2014 - 10:37

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