Antarctic Ice Discussion

[Gray-Wolf]

This is why I hold such concerns for any partial collapse of the ross embayment. The physical pressures that gravity exerts on the ice are only held in check by the 'ice dams' that are the ice shelfs. Remove them and gravity has it's way , no matter what temp does in the interior!

Once we discover how far the warm southern ocean has now penetrated beyond Pine , and toward Ross, we'll have a much better idea as to how long we have before we see major alterations to Ross Embayment..... and the rapid sea level hikes this partial collapse preludes.

[Gray-Wolf]

First sight of 'My Crack' for the year!!!

The bottom of the image is Roosevelt Island and the top the middle of Ross. It is a cropped 250m image from Aqua so you can figure the scale of the thing.

To my eyes the crack is wider than before and has a second crack, further to the top of the image , between it and the ice cliff front of the shelf.

[knocker]

Press Release - Why Antarctic sea ice cover has increased under the effects of climate change

The first direct evidence that marked changes to Antarctic sea ice drift have occurred over the last 20 years, in response to changing winds, is published this week in the journal Nature Geoscience. Scientists from NERC’s British Antarctic Survey (BAS) and NASA’s Jet Propulsion Laboratory (JPL), Pasadena California explain why, unlike the dramatic losses reported in the Arctic, the Antarctic sea ice cover has increased under the effects of climate change

http://www.antarctica.ac.uk/press/press_releases/press_release.php?id=1967

[laserguy]

Press Release - Why Antarctic sea ice cover has increased under the effects of climate change

[Gray-Wolf]

Why , when the data is explained so clearly, do you still choose to ignore the conclusions LG?

We always knew that the changes under AGW would be wide and varied including some cold records being driven by alterations to global circulation allowing for increased mobility of polar air masses. We knew that a warmer atmosphere, being able to hold more moisture, would lead to increased snowfall events (as with rainfall events). None of this is counter intuitive?

Our impacts on the Ozone are documented and have been easy to see since the B.A.S. brought us those first shocking images of the hole over Antarctica. Our meteorological understanding of temp forcings in the Stratosphere, and the impacts this drives at the surface, are also a well studied phenomina (better understood thean some aspects of the climate system in fact!)

None of what is being said is Voodoo, just plain science. If you have issues with the science then let us all into what your concerns are?

[Interitus]

Our impacts on the Ozone are documented and have been easy to see since the B.A.S. brought us those first shocking images of the hole over Antarctica. Our meteorological understanding of temp forcings in the Stratosphere, and the impacts this drives at the surface, are also a well studied phenomina (better understood thean some aspects of the climate system in fact!)

On the contrary the mechanisms involved in the Antarctic are not completely understood.

The article above confirms circulation changes on the ice pack and papers such as "Stratospheric Ozone Depletion: The Main Driver of Twentieth-Century Atmospheric Circulation Changes in the Southern Hemisphere" (2011) http://atmos.snu.ac.kr/swson/papers/Polvani-etal-JCLI2011.pdf reiterates that ozone depletion has affected the whole southern hemisphere circulation, with an impact 2-3 times greater than greenhouse forcing.

However on the other hand, it is not totally clear what is going on as for example highlighted in this paper "Has the ozone hole contributed to increased Antarctic sea ice extent?" (2010) http://www.atmosp.physics.utoronto.ca/people/sigmond/papers/sigmond_fyfe_2010_grl.pdf which concludes -

It is presently unclear why the observed Southern Hemisphere SIE trends are so different from those in the Northern Hemisphere. Previous studies have suggested that the cause might be related to atmospheric circulation changes induced by the stratospheric ozone hole. The results in this study are not consistent with this view and highlight the need for continued investigations of Antarctic SIE trends.

A key point from this paper "Antarctic climate response to stratospheric ozone depletion in a fine resolution ocean climate model" (2012) http://www.columbia....ni-GRL-2012.pdf is that -

"It is unlikely that ozone depletion caused recent Antarctic sea ice expansion"

And the authors of this paper "Mitigation of 21st century Antarctic sea ice loss by stratospheric ozone recovery" (2012) - http://scholar.googl...l=en&as_sdt=0,5

compared forecast ensembles with and without ozone recovery and found that "sea ice loss is ~33% greater for the ensemble in which the stratospheric ozone recovery does not take place, and this effect is statistically significant. Our results, which confirm a previous study dealing with ozone depletion, suggest that ozone recovery will substantially mitigate Antarctic sea ice loss in the coming decades.

Clearly this is still an area of ongoing research and discovery and modelling of the situation requires some degree of refinement yet.

Edited November 12, 2012 by Interitus

[Coast]

Press Release - Why Antarctic sea ice cover has increased under the effects of climate change

Here's the Guardians take on that:

The mystery of the expansion of sea ice around Antarctica, at the same time as global warming is melting swaths of Arctic sea ice, has been solved using data from US military satellites.

Two decades of measurements show that changing wind patterns around Antarctica have caused a small increase in sea ice, the result of cold winds off the continent blowing ice away from the coastline.

"Until now these changes in ice drift were only speculated upon using computer models," said Paul Holland at the British Antarctic Survey. "Our study of direct satellite observations shows the complexity of climate change. "The Arctic is losing sea ice five times faster than the Antarctic is gaining it, so, on average, the Earth is losing sea ice very quickly. There is no inconsistency between our results and global warming."

The extent of sea ice is of global importance because the bright ice reflects sunlight far more than the ocean that melting uncovers, meaning temperature rises still further. This summer saw a record low in Arctic sea ice since satellite measurements began 30 years ago. Holland said the changing pattern of sea ice at both poles would also affect global ocean circulation, with unknown effects. He noted that while Antarctic sea ice was growing, the Antarctic ice cap – the glacier and snow pack on the continent – was losing mass, with the fresh water flowing into the ocean.

The research on Antarctic sea ice, published in Nature Geoscience, revealed large regional variations. In places where warm winds blowing from the tropics towards Antarctica had become stronger, sea ice was being lost rapidly. "In some areas, such as the Bellingshausen Sea, the sea ice is being lost as fast as in the Arctic," said Holland. But in other areas, sea ice was being added as sea water left behind ice being blown away from the coast froze. The net effect is that there has been an extra 17,000 sq km of sea ice each year since 1978 – about a tenth of a percent of the maximum sea ice cover.

Antarctica is a continent surrounded by an ocean, whereas the Arctic is an ocean surrounded by a continent. For that reason, said Holland, sea ice was not able to expand by the same mechanism in the Arctic as at the southern pole, because if winds pushed the ice away from the pole it quickly hit land. Holland did the research with Ron Kwok at Nasa's jet propulsion laboratory in California, where maps of sea ice movements were created from more than 5m individual daily measurements collected over 19 years. The maps showed, for the first time, the long-term changes in sea ice drift around Antarctica.

Kwok said: "The Antarctic sea ice cover interacts with the global climate system very differently than that of the Arctic, and these results highlight the sensitivity of the Antarctic ice coverage to changes in the strength of the winds around the continent."

http://www.guardian.co.uk/environment/2012/nov/11/poles-scientists-antarctic-sea-ice

[BornFromTheVoid]

3 new videos from the latest ice bridge mission from NASA

http://svs.gsfc.nasa.gov/vis/a010000/a011100/a011135/

[knocker]

Following on from that we now can confirm that GW has two cracks.

On Monday, NASA released a new video of the latest aerial observations of the crack — located on Antarctica’s Pine Island Glacier. What NASA discovered was not only has the crack widened and lengthened, but it’s also led to a smaller, secondary crack.

http://idealab.talkingpointsmemo.com/2012/11/nasa-spots-new-crack-on-nyc-sized-iceberg-in-antarctica.php

[neville]

Was hoping to find a better source than Yahoo news, but this showed up when I logged on to my email account this evening.

http://uk.news.yahoo...-232054453.html

Obviously comes from the NASA info knocker posted, but they claim only half a mile to go before the berg is free.

Edited November 22, 2012 by neville

[Gray-Wolf]

http://news.yahoo.com/texas-m-study-shows-ice-melt-antarctica-aided-211500464.html

At last more news on the warm bottom waters!

Reading between the lines it appears that the warm waters are at Ross but the melt outflow ,from the mountains to it's south (NASA saw melt up to 1 mile up in those mountains back in 05') and the Glaciers draining the E.A.I.S., over summer/Autumn overpowers this influx.

Maybe I should be looking for another winter breakup as the water undercuts those massive ice cliffs (seabed to up to 200ft above the water)?

[Gray-Wolf]

It appears that this full moon tide might have been enough to finish the crack on P.I.G.? The latest MODIS images show the crack now completely across the Glacier and even the hint of rotation similar to what we saw with the Peterman calve this summer (as though it has gone and is just stuck on the bottom....if so it will rotate further and slip off the obstruction floating out into the ocean)

[Gray-Wolf]

The current storm over Weddell seems to be both messing up the ice;

http://lance-modis.e...12340.terra.4km

and transporting it out into the Southern oceans on the Northerlies (now that the larsens no longer act as a 'gate' across the top of the peninsula there?). Will we be seeing the lowest ice extent ever recorded there this southern summer? A couple more storms sat like this one and i could see us losing some of the only perennial ice in Antarctica!

For those not sure of the significance Weddell usually holds ice all summer long with only a couple of polynias at the coasts showing open water there. Since the collapse of the Larsen suite of Ice Shelfs the top of the peninsula is no longer restricted by an expanse of shelf ice and so ice transported by the left of the storms can now travel up the peninsula and out into the southern ocean.

If you flick back the mosaic a few days you can watch the storm start to smash up the ice in the sea area and start transport out of the basin.

Would it not be a tad ironic were Antarctica to post a record ice min this southern summer? The only wat for that to occur is by losses to Weddell and Ross seas (though Ross ice cover, at ice min and max, has been on the decline throughout the noughties?).

Edited December 5, 2012 by Gray-Wolf

[knocker]

Warm Sea Water Is Melting Antarctic Glaciers

ScienceDaily (Dec. 6, 2012) — The ice sheet in West Antarctica is melting faster than expected. New observations published by oceanographers from the University of Gothenburg and the US may improve our ability to predict future changes in ice sheet mass. The study was recently published in the journal Nature Geoscience.

A reduction of the ice sheets in Antarctica and Greenland will affect the water levels of the world's oceans.

It is therefore problematic that we currently have insufficient knowledge about the ocean circulation near large glaciers in West Antarctica. This means that researchers cannot predict how water levels will change in the future with any large degree of certainty.

"There is a clear reduction in the ice mass in West Antarctica, especially around the glaciers leading into the Amundsen Sea," says researcher Lars Arneborg from the Department of Earth Sciences at the University of Gothenburg.

http://www.sciencedaily.com/releases/2012/12/121206094505.htm

[knocker]

Massive crevasses and bendable ice affect stability of Antarctic ice shelf, CU research team finds

Gaping crevasses that penetrate upward from the bottom of the largest remaining ice shelf on the Antarctic Peninsula make it more susceptible to collapse, according to University of Colorado Boulder researchers who spent the last four Southern Hemisphere summers studying the massive floating sheet of ice that covers an area twice the size of Massachusetts.

But the scientists also found that ribbons running through the Larsen C Ice Shelf – made up of a mixture of ice types that, together, are more prone to bending than breaking – make the shelf more resilient than it otherwise would be.

The research team from CU-Boulder's Cooperative Institute for Research in the Environmental Sciences presented the findings Dec. 6 at the American Geophysical Union's annual meeting in San Francisco.

The Larsen C Ice Shelf is all that's left of a series of ice shelves that once clung to the eastern edge of the Antarctic Peninsula and stretched into the Weddell Sea. When the other shelves disintegrated abruptly – including Larsen A in January 1995 and Larsen B in February 2002 – scientists were surprised by the speed of the breakup.

Researchers now believe that the catastrophic collapses of Larsen A and B were caused, at least in part, by rising temperatures in the region, where warming is increasing at six times the global average. The Antarctic Peninsula warmed 4.5 degrees Fahrenheit since the middle of the last century.

The warmer climate increased meltwater production, allowing more liquid to pool on top of the ice shelves. The water then drained into surface crevasses, wedging them open and cracking the shelf into individual icebergs, which resulted in rapid disintegration.

But while the meltwater may have been responsible for dealing the final blow to the shelves, researchers did not have the opportunity to study how the structure of the Larsen A and B shelves may have made them more vulnerable to drastic breakups – or protected the shelves from an even earlier demise.

CU-Boulder researchers did not want to miss the same opportunity on the Larsen C shelf, which covers more than 22,000 square miles of sea.

"It's the perfect natural laboratory," said Daniel McGrath, a doctoral student in the Department of Geography and part of the CIRES research team. "We wanted to study this shelf while it's still stable in order to get a better understanding of the processes that affect ice shelf stability."

McGrath worked with CIRES colleagues over the last four years to study the Larsen C shelf in order to better understand how the warming climate may have interacted with the shelf's existing structure to increase its vulnerability to a catastrophic collapse.

McGrath presented two of the group's key findings at the AGU meeting. The first was the role that long-existing crevasses that start at the base of the shelf and propagate upward – known as basal crevasses – play in making the shelf more vulnerable to disintegration. The second relates to the way a type of ice found in areas called suture zones may be protecting the shelf against a breakup.

The scientists used ground penetrating radar to map out the basal crevasses, which turn out to be massive. The yawning cracks can run for several miles in length and can penetrate upwards for more than 750 feet. While the basal crevasses have been a part of Larsen C for hundreds of years, the interaction between these features and a warming climate will likely make the shelf more susceptible to future disintegration. "They likely play a really important role in ice-shelf disintegration, both past and future," McGrath said.

The research team also studied the impact of suture zones in the ice shelf. Larsen C is fed by 12 distinct glaciers, which dump a steady flow of thick ice into the shelf. But the promontories of land between the glacial outlets, where ice does not flow into the shelf, allow for the creation of ribbon-like suture zones, which knit the glacial inflows together and which turn out to be important to the ice shelf's resilience. "The ice in these zones really holds the neighboring inflows together," McGrath said.

The suture zones get their malleable characteristic from a combination of ice types. A key component of the suture zone mixture is formed when the bottoms of the 12 glacial inflows begin to melt. The resulting freshwater is more buoyant than the surrounding seawater, so it rises upward to the relatively thinner ice zones between the glacial inflows, where it refreezes on the underside of the shelf and contributes to the chaotic ice structure that makes suture zones more flexible than the surrounding ice.

It turns out that the resilient characteristics of the suture zones keep cracks, including the basal crevasses, from spreading across the ice shelf, even where the suture zone ice makes up a comparatively small amount of the total thickness of the shelf. The CIRES team found that at the shelf front, where the ice meets the open sea, suture zone ice constitutes only 20 percent of the total thickness of the shelf but was still able to limit the spread of rifts through the ice. "It's a pretty small part of the total ice thickness, and yet, it still has this really important role of holding the ice shelf together," McGrath said.

http://www.eurekalert.org/pub_releases/2012-12/uoca-mca120712.php

[knocker]

More ice loss through snowfall on Antarctica

Stronger snowfall increases future ice discharge from Antarctica. Global warming leads to more precipitation as warmer air holds more moisture – hence earlier research suggested the Antarctic ice sheet might grow under climate change. Now a study published in Nature shows that a lot of the ice gain due to increased snowfall is countered by an acceleration of ice-flow to the ocean. Thus Antarctica's contribution to global sea-level rise is probably greater than hitherto estimated, the team of authors from the Potsdam Institute for Climate Impact Research (PIK) concludes.

"Between 30 and 65 percent of the ice gain due to enhanced snowfall in Antarctica is countervailed by enhanced ice loss along the coastline," says lead-author Ricarda Winkelmann. For the first time, an ensemble of ice-physics simulations shows that future ice discharge is increased up to three times because of additional precipitation in Antarctica under global warming. "The effect exceeds that of surface warming as well as that of basal ice-shelf melting," Winkelmann says.

During the last decade, the Antarctic ice-sheet has lost volume at a rate comparable to that of Greenland. "The one certainty we have about Antarctica under global warming is that snowfall will increase," Winkelmann explains. "Since surface melt might remain comparably small even under strong global warming, because Antarctica will still be a pretty chilly place, the big question is: How much more mass within the ice sheet will slowly but inexorably flow off Antarctica and contribute to sea-level rise, which is one of the major impacts of climate change."

Since snowfall on the ice masses of Antarctica takes water out of the global water cycle, the continent's net contribution to sea-level rise could be negative during the next 100 years – this is what a number of global and regional models suggest. The new findings indicate that this effect to a large extent is offset by changes in the ice-flow dynamics. Snow piling up on the ice is heavy and hence exerts pressure – the higher the ice the more pressure. Because additional snowfall elevates the grounded ice-sheet but less so the floating ice shelves, it flows more rapidly towards the coast of Antarctica where it eventually breaks off into icebergs and elevates sea level.

A number of processes are relevant for ice-loss in Antarctica, most notably to sub-shelf melting caused by warming of the surrounding ocean water. These phenomena explain the already observed contribution to sea-level rise.

"We now know that snowfall in Antarctica will not save us from sea-level rise," says second author Anders Levermann, research domain co-chair at PIK and a lead author of the sea-level change chapter of the upcoming IPCC's 5th assessment report. "Sea level is rising – that is a fact. Now we need to understand how quickly we have to adapt our coastal infrastructure; and that depends on how much CO2 we keep emitting into the atmosphere," Levermann concludes.

http://www.eurekalert.org/pub_releases/2012-12/pifc-mil121012.php

[Gray-Wolf]

We were already seeing the issues involved with losing the Shelf systems that used to hold back the interior ice but the threat of heavy ,wet, snow squashing the ice down and out will just compound those issues. Because of the compression of snow into ice the loss of ice will involve far more water than any plausible increase of snowfall?

How is it that though we know we are losing a similar ice mass to Greenland (and at the same rate of increase) we still hear about the 8 weeks of sea ice that pushes some areas into positive anoms?

When we get to mid summer none of the sea ice remains but the losses remain? I'd wager that the volume of 'increase' is less than a fifth of the ice lost over the period it sits in the water at winters end?

Are these folk truely confused or are they trying to twist things to suit an agenda not based in truth?

[knocker]

For anyone who is interested the link to the Lake Ellsworth web site.

http://www.ellsworth.org.uk/

[knocker]

Good job we are in a cooling period!

Study shows rapid warming on the West Antarctic Ice Sheet

COLUMBUS, Ohio—In a discovery that raises further concerns about the future contribution of Antarctica to sea level rise, a new study finds that the western part of the ice sheet is experiencing nearly twice as much warming as previously thought.

The temperature record from Byrd Station, a scientific outpost in the center of the West Antarctic Ice Sheet (WAIS), demonstrates a marked increase of 4.3 degrees Fahrenheit (2.4 degrees Celsius) in average annual temperature since 1958—that is, three times faster than the average temperature rise around the globe.

This temperature increase is nearly double what previous research has suggested, and reveals—for the first time—warming trends during the summer months of the Southern Hemisphere (December through February), said David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd Polar Research Center.

The findings were published online this week in the journal Nature Geoscience.

"Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does," said Bromwich.

http://www.eurekaler...u-ssr122012.php

Edited December 23, 2012 by knocker

[Gray-Wolf]

When we look at the volume of ice from shelves that has been lost since the 90's we have to accept that something different is occuring esp. with the age of some of the shelfs lost?

Sadly the sceptic fillibuster about record seasonal sea ice growth makes it sound , to the unenlightened, that Antarctca is cooling and ice mass is increasing when nothing could be further from the truth!

I have to wonder at the logical conclusion of all the twisted disinformation that the group has put out over the past few years? Can they really think that the facts on the ground can be hidden from the world?

[4wd]

If you read the whole piece they have filled in missing data with computer generated data.

Then extrapolated the invented warming from one station over about a quarter of the continent.

This is not terribly convincing.

The other black dots are other weather stations which curiously do not show the warming.

[4wd]

This is a graph from the actual data.

From this the BBC and others have come up with a story about scary warming in the Antarctic.

It's worth noting that the highest temperature in the record is about -10C

The study is truly an astonishing invention and would perhaps have been better released on 1st April.

[pottyprof]

WOW!! Fancy someone recording warmer temperatures where there is volcanic activity... I'm shocked...

Edited December 24, 2012 by pottyprof

[knocker]

If you read the whole piece they have filled in missing data with computer generated data.

Could you please supply a link to the whole piece as I don't subscribe to Nature Geoscience.

The New York Times take on it

Eric J. Steig, a University of Washington researcher who led the 2009 work, said in an interview that he considered his paper to have been supplanted by the new research. “I think their results are better than ours, and should be adopted as the best estimate,†he said. He noted that the new Byrd record matches a recent temperature reconstruction from a nearby borehole in the ice sheet, adding confidence in the findings.

Much of the warming discovered in the new paper happened in the 1980s, around the same time the planet was beginning to warm briskly. More recently, Dr. Bromwich said, the weather in West Antarctica seems to have become somewhat erratic. In the summer of 2005, the interior of West Antarctica warmed enough for the ice to undergo several days of surface melting.

Well he's right there. Intensive scrutiny from a farmer in Yorkshire. Better scrap the paper.

[BornFromTheVoid]

The NCAR/UCAR take on it

http://www2.ucar.edu...g-more-expected

"Our results indicate that temperature increases during the past half century have been almost twice what we previously thought, placing West Antarctica among the fastest warming regions on Earth,†says NCAR scientist Andrew Monaghan, a co-author. “A growing body of research shows that the West Antarctic Ice Sheet is changing at an alarming rate, with pressure coming from both a warming ocean and a warming atmosphere.â€