New research sheds light on Antarctica's melting Pine Island Glacier

Jun 20, 2010

New results from an investigation into Antarctica's potential contribution to sea level rise are reported this week (Sunday 20 June) by scientists from the British Antarctic Survey (BAS), Lamont-Doherty Earth Observatory (LDEO) and the National Oceanography Centre in the journal Nature Geoscience.

Thinning ice in West Antarctica is currently contributing nearly 10 per cent of global and scientists have identified Pine Island Glacier (PIG) as a major source. As part of a series of investigations to better understand the impact of melting ice on sea level an exciting new discovery has been made. Using Autosub (an autonomous underwater vehicle) to dive deep and travel far beneath the pine Island Glacier's floating , scientists captured ocean and measurements, which revealed a 300m high ridge (mountain) on the sea floor.

Pine Island Glacier was once grounded on (sitting on top of) this underwater ridge, which slowed its flow into the sea. However, in recent decades it has thinned and disconnected from the ridge, allowing the glacier to move ice more rapidly from the land into the sea. This also permitted deep warm ocean water to flow over the ridge and into a widening cavity that now extends to an area of 1000 km2 under the ice shelf. The warm water, trapped under the ice, is causing the bottom of the ice shelf to melt, resulting in continuous thinning and acceleration of the glacier.

Lead author Dr Adrian Jenkins of said, "The discovery of the ridge has raised new questions about whether the current loss of ice from Pine Island Glacier is caused by recent or is a continuation of a longer-term process that began when the glacier disconnected from the ridge.

"We do not know what kick-started the initial retreat from the ridge, but we do know that it started some time prior to 1970. Since detailed observations of Pine Island Glacier only began in the 1990s, we now need to use other techniques such as ice core analysis and computer modelling to look much further into the glacier's history in order to understand if what we see now is part of a long term trend of ice sheet contraction. This work is vital for evaluating the risk of potential wide-spread collapse of West Antarctic glaciers."

Co-author Stan Jacobs adds: "Since our first measurements in the Amundsen Sea, estimates of Antarctica's recent contributions to sea level rise have changed from near-zero to significant and increasing. Now finding that the PIG's grounding line has recently retreated more than 30 km from a shallow ridge into deeper water, where it is pursued by a warming ocean, only adds to our concern that this region is indeed the 'weak underbelly' of the West Antarctic Ice Sheet. Increased melting of continental ice also appears to be the primary cause of persistent ocean freshening and other impacts, both locally and downstream in the Ross Sea."

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More information: Nature Geoscience paper: Observations beneath Pine Island Glacier West Antarctica and implications for its retreat

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User comments : 15

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Stellarparadox
1.5 / 5 (15) Jun 20, 2010
But there has been no sea rise measurement in decades, when did it become mandatory for real science to bow to the Algore types who have no evidence for global warming at all, to accept it? I know, follow the money.
Kev_C
4.4 / 5 (7) Jun 20, 2010
Real science has not bowed to the Al Gore types at all. This is real evidence of glacial ice moving into the open ocean at an increasing rate of knots. If the volume of ice (that which is above sea level) is measured it constitutes the amount of additional water in frozen form that will add to the level of the seas as the glacier calves at the leading edge. The effect will only be fully noticeable when there are no glaciers left and the continental plates reflex after the glacial ice weight has been removed. Once everything has settled down and the plates have stopped moving vertically then the true level of the seas will be seen. It will take a long time to happen but the real issue is that we need to act today to stop the rampant climate change which will cause the positive feedback loops that will exacerbate this process of melting glaciers. Believe it or not there is actually no money in this process unless you intend to mine the minerals once they have been exposed.
PinkElephant
5 / 5 (6) Jun 20, 2010
@Stellarparadox,

How hard would it be to first do a simple web search, before posting blatant falsehoods? Here, I did you work, such as it was, for you:

http://en.wikiped...vel_rise
MikPetter
5 / 5 (5) Jun 20, 2010
some additional information from the BBC news article on the same story

"In 2009, a study of satellite measurements of Pine Island Glacier, which is one of the largest in Antarctica, revealed the surface of the ice was falling at a rate of up to 16m a year.

It added that the glacier was thinning four times faster than it was a decade earlier."
IrishMo48
3 / 5 (4) Jun 21, 2010
Melting ice or shattering, (from huge wave action), ice.

So I checked out the article to see what the reported "warm" water temps actually were ... And this was all I could find ...

"Adding to the problems are the sub zero water temperatures and the crushing pressures at 1000 m depth."

Last time I checked, not a whole lot of ice melts at zub zero temperatures.

This appears to be nothing more than another alarmist article making supposition mountains out of non-existent mole hills.
TegiriNenashi
1 / 5 (2) Jun 21, 2010
Speaking of Amundsen, he established his base at
http://en.wikiped...f_Whales
Think of it: a structure in the ice shelf that exists for a century! This is incredible given that the ice shelf itself expands at rate 1.5 meters a day. So on average there is not really a single change in the vast area of Antarctic worth reporting to. Certainly, if you focus hard enough you'll find few artifacts with some dynamics. However, finding a single shrinking glassier out of a thousand is would not earn you the Nobel prize (the real one, not peace), sorry.
Skeptic_Heretic
1 / 5 (2) Jun 21, 2010
Last time I checked, not a whole lot of ice melts at zub zero temperatures.
Then the last time you checked you checked a crappy source. The primary loss of ice is due to ablation, not melt. Once you calve(ablation) the ice into the sub zero sea it floats into warmer water where it melts.
However, finding a single shrinking glassier out of a thousand is would not earn you the Nobel prize (the real one, not peace), sorry.
You might want to give the NASA reconstruction a quick peek and tell me what you see. Is it prize worthy?
PinkElephant
5 / 5 (2) Jun 21, 2010
@IrisMo48,
Last time I checked, not a whole lot of ice melts at zub zero temperatures.
Add a little salt, and you'd be surprised.
FadingFast
3 / 5 (4) Jun 21, 2010
It seems disingenuous of the authors of this piece not to even mention the recent(2008)discovery (by BAS investigators, no less) of a huge, active, sub-glacial volcano in the same area and believed to be at least a partial cause of the melting:
http://www.antarc...p?id=341

Just another example of climate researchers ignoring data inconvenient to their quest to make CO2 the root of all climate evil?
PinkElephant
4 / 5 (3) Jun 21, 2010
@FadingFast,

Well spotted. But, from the link you provided:
The flow of this glacier towards the coast has speeded up in recent decades and it may be possible that heat from the volcano has caused some of that acceleration. However, it cannot explain the more widespread thinning of West Antarctic glaciers that together are contributing nearly 0.2mm per year to sea-level rise. This wider change most probably has its origin in warming ocean waters.
So perhaps there's no way around the warming ocean trend. And perhaps, since 2008 it's become apparent that the dormant volcano isn't providing all that much heat?
FadingFast
2.3 / 5 (3) Jun 21, 2010
@PinkElephant
Perhaps, perhaps not. The point is they didn't even mention it let alone provide any rationale as to why it's not a factor.
"Hide the decline, hide the decline"
PinkElephant
1 / 5 (1) Jun 21, 2010
"Hide the decline, hide the decline"
Do you even know what that refers to?
Skeptic_Heretic
1 / 5 (2) Jun 21, 2010
It seems disingenuous of the authors of this piece not to even mention the recent(2008)discovery (by BAS investigators, no less) of a huge, active, sub-glacial volcano in the same area and believed to be at least a partial cause of the melting:
http://www.antarc...p?id=341

Just another example of climate researchers ignoring data inconvenient to their quest to make CO2 the root of all climate evil?

Wasn't exactly ignored, it was accounted for. The funny thing about there being an active volcano is that one could infer that there has been an active volcano there for quite a long time. Secondly what would awaken a volcano that had been dormant for a long time? Well, one potential reason would be a large increase or decrease in mantle pressure caused by hmm..... calving ice not being replaced and resulting in tectonic rebound.
jsa09
5 / 5 (2) Jun 21, 2010
I liked this article because the study seemed to be focused on the science rather than the politics.

Sure the article may have been assuming that the oceans were overall warming but... they did not say it was all the fault of AGW. Instead they looked for what was actually happening. The final conclusion was inconclusive but that is common with these sorts of studies.

Certainly it appears that the shelf has shifted at some time prior to 1970 and furthermore that perhaps the prevailing currents are causing it to slowly melt and as a consequence there is some flow on of global sea level rise of some tiny amount.
Shootist
1 / 5 (1) Jun 26, 2010
Think about all of that gold just lying at the bottoms of those melted glacier beds. Just begging to be mined.

Oh, the humanity.

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