Previous rapid thinning of Pine Island Glacier sheds light on future Antarctic ice loss

Feb 20, 2014
Sample from Maish Nunatak, Antarctica. Credit: James Smith, British Antarctic Survey

New research, published this week in Science, suggests that the largest single contributor to global sea level rise, a glacier of the West Antarctic Ice Sheet, may continue thinning for decades to come. Geologists from the UK, USA and Germany found that Pine Island Glacier (PIG), which is rapidly accelerating, thinning and retreating, has thinned rapidly before. The team say their findings demonstrate the potential for current ice loss to continue for several decades yet.

Their findings reveal that 8000 years ago the glacier thinned as fast as it has in recent decades, providing an important model for its future behaviour. The glacier is currently experiencing significant acceleration, thinning and retreat that is thought to be caused by 'ocean-driven' melting; an increase in warm ocean water finding its way under the ice shelf.

After two decades of rapid ice loss, concerns are arising over how much more ice will be lost to the ocean in the future. Model projections of the future of PIG contain large uncertainties, leaving questions about the rate, timing and persistence of future . Rocks exposed by retreating or thinning glaciers provide evidence of past change, which helps scientists to predict possible future change. The geologists used highly sensitive dating techniques, pioneered by one of the team, to track the thinning of PIG through time, and to show that the past thinning lasted for several decades.

Lead author Joanne Johnson from the British Antarctic Survey (BAS) said:

"Our geological data show us the history of Pine Island Glacier in greater detail than ever before. The fact that it thinned so rapidly in the past demonstrates how sensitive it is to environmental change; small changes can produce dramatic and long-lasting results. Based on what we know, we can expect the rapid ice loss to continue for a long time yet, especially if ocean-driven melting of the in front of Pine Island Glacier continues at current rates,"

Professor Mike Bentley, a co-leader of the project based at Durham University said:

"This paper is part of a wide range of international scientific efforts to understand the behaviour of this important glacier. The results we're publishing are the product of long days spent sampling rocks from mountains in Antarctica, coupled to some exceptionally precise and time-consuming laboratory analyses. The results are clear in showing a remarkably abrupt thinning of the glacier 8000 years ago".

Explore further: Pine Island Glacier sensitive to climatic variability

More information: Rapid thinning of Pine Island Glacier in the early Holocene by J. S. Johnson, M. J. Bentley, J. A. Smith, R. C. Finkel, D. H. Rood, K. Gohl, G. Balco, R. D. Larter, J. M. Schaefer is published in Science on Thursday 20 February 2014. www.sciencemag.org/lookup/doi/… 1126/science.1247385

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User comments : 3

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TegiriNenashi
1 / 5 (6) Feb 20, 2014
How can they say "warm ocean water" with straight face when antarctic sea ice cover is expanding?
Captain Stumpy
5 / 5 (2) Feb 21, 2014
How can they say "warm ocean water" with straight face when antarctic sea ice cover is expanding

@TegiriNenashi
see http://phys.org/n...ice.html
Climate change in Antarctica means melting of the ice sheet, but also an increase in sea ice. While the extra sea ice in Commonwealth Bay is not directly due to climate change, the site offers a unique glimpse of how it affects the ecosystems

&
the water below the sea ice has become less saline.

&
freshwater freezes more easily than saltier water, the drop in salinity below the sea ice means that it is easier to form new sea ice

might just have something to do with it...
The glacier is currently experiencing significant acceleration, thinning and retreat that is thought to be caused by 'ocean-driven' melting; an increase in warm ocean water finding its way under the ice shelf

logical to me
is English your second language?
Runrig HAS pointed this out before MANY times...
TegiriNenashi
1 / 5 (3) Feb 21, 2014
is English your second language?


You might have been lost: this is a science site, where people operate numbers, not words. You can invent all kind of silly excuses (salinity, ozone hole, yeah, right), but the facts are not on your side:
1. Freshwater melt amount to perhaps to 1/250000 of Southern Ocean volume
2. There is no evidence that glassier melting in Antarctic have been increased (so even this tiny volume is something that didn't really change)
3. Look at the graphs (from the British Antarctic Survey themselves)
http://www.nerc-b...rend.pdf
http://www.nerc-b...rend.pdf
Do you see any melting? I don't.