First complete map of the speed and direction of ice flow in Antarctica, derived from radar interferometric data. Image credit: NASA/JPL-Caltech/UCI
PASADENA, Calif. – NASA-funded researchers have created the first complete map of the speed and direction of ice flow in Antarctica. The map, which shows glaciers flowing thousands of miles from the continent’s deep interior to its coast, will be critical for tracking future sea-level increases from climate change. The team created the map using integrated radar observations from a consortium of international satellites.
“This is like seeing a map of all the oceans’ currents for the first time. It’s a game changer for glaciology,” said Eric Rignot of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and the University of California (UC), Irvine. Rignot is lead author of a paper about the ice flow published online Thursday in Science Express. “We are seeing amazing flows from the heart of the continent that had never been described before.”
Rignot and UC Irvine scientists Jeremie Mouginot and Bernd Scheuchl used billions of data points captured by European, Japanese and Canadian satellites to weed out cloud cover, solar glare and land features masking the glaciers. With the aid of NASA technology, the team painstakingly pieced together the shape and velocity of glacial formations, including the previously uncharted East Antarctica, which comprises 77 percent of the continent.
Like viewers of a completed jigsaw puzzle, the scientists were surprised when they stood back and took in the full picture. They discovered a new ridge splitting the 5.4 million-square-mile (14 million-square-kilometer) landmass from east to west.
The team also found unnamed formations moving up to 800 feet (244 meters) annually across immense plains sloping toward the Antarctic Ocean and in a different manner than past models of ice migration.
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner, NASA’s cryospheric program scientist in Washington. “That’s critical knowledge for predicting future sea level rise. It means that if we lose ice at the coasts from the warming ocean, we open the tap to massive amounts of ice in the interior.”
The work was conducted in conjunction with the International Polar Year (IPY) (2007-2008). Collaborators worked under the IPY Space Task Group, which included NASA; the European Space Agency (ESA); Canadian Space Agency (CSA); Japan Aerospace Exploration Agency; the Alaska Satellite Facility in Fairbanks; and MacDonald, Dettwiler and Associates of Richmond, British Columbia, Canada. The map builds on partial charts of Antarctic ice flow created by NASA, CSA and ESA using different techniques. “To our knowledge, this is the first time that a tightly knit collaboration of civilian space agencies has worked together to create such a huge dataset of this type,” said Yves Crevier of CSA. “It is a dataset of lasting scientific value in assessing the extent and rate of change in polar regions.”
For a video animation of the new Antarctic map, visit: http://1.usa.gov/poJq1P .
For more information about NASA and agency programs, visit: http://www.nasa.gov .
JPL is managed for NASA by the California Institute of Technology in Pasadena.
“The team also found unnamed formations moving up to 800 feet (244 meters) annually across immense plains sloping toward the Antarctic Ocean and in a different manner than past models of ice migration.”
Observations trump models again!
So these ice shelves are supposed to hold back the entire continent of ice cap?
And here I thought that the map was indicating an ice tsunami, with the speed picking up as the depth decreased.
40 years ago, we learned in jr. high that glaciers gouged out U-shaped canyons as the ice slid along the bottom. But, these ‘scientists’ are now surprised by this?
Oh, it’s alwasy about climate change and rising sea levels spoiling the view.
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner”
Fundamentally new? WTF? If this guy is not being misquoted then he has definitely led a very sheltered life.
Cool……… 🙂
Waiting for the informed comments detailing flaws in assumptions about “Climate Change” and Willis to do some sort of magical mathematical analysis which clearly shows that there is more ice than there used to be!
“Bloke down the pub says:
August 23, 2011 at 1:17 am”
I missed that because I could not believe the statement from the article in the post I made, but I had a real chuckle about that one too. I despair when I read stuff like this.
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,”
Fundamentally new! I can’t even hazard a guess as to what he thought the fundamentals were before his new discovery!
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on”
I’m wondering what else it could possibly be slipping on.. banana peels? Or maybe they were thinking the ground moves with it.. Or it flies through the air?
Seriously, I’d love to be completely dumb and miss whatever obvious mode of transport it moves with.
Oh come on! You gotta be f’n joking right? Hey Wagner, when your big press quote looks like something right out of an Onion satire or April Fool’s joke, something is seriously wrong! Thomas Wagner is a NASA scientist based in Washington D.C.? Houston, we’ve got a problem right there. What’s he researching? Potomac mosquitoes or taxpayer funded grants?
It sure sounds to me like this guy and his team are intentionally wording things to imply that they actually discovered something here, almost like they are taking credit for something real scientists have done already. Doesn’t he get the NatGeo or History channel (or WUWT)? Been there done that. Striations on Central Park bedrock. Great lakes carved by glacial movement and filled from meltwater. Likewise for countless other glacial and post-glacial locations all over the Earth. Why doesn’t he also take credit for discovering gravity too?
People *should* click that link to familiarize themselves with the real propaganda end-product here. An animation that makes it look like Antarctica is running like Colorado River rapids. Get used to it because it is ready-made for alarmist websites. Here is their disclaimer …
That is what the whole thing is about. Millions or Billions of dollars spent on satellites and super-computer time and countless man-hours to make that little animation and a few press releases and webpages. Taxpayer funded AGW hysteria propaganda. This theme is running rampant in all FedGov agencies, NSIDC with Serreze, NASA with Hansen and Gavin, NOAA, EPA, DEC, etc. Perhaps the only answer is to shut them all down, fire everyone, cancel their pensions and then, maybe, re-open one or two of them under new non-union, non-political, non-AGW management.
“ice moves by slipping along the ground it rests on”
While common sense might tell you this is a common sense statement, it is bloody false. Glaciers don’t “slip”, they grind their way through the bedrock because they are pushed by the enormous weight of the ice from higher up. Glaciers dug the fjords in Norway, and they did not do this by “slipping”, but by grinding the rock under them and carrying the sand, the pebbles or even boulders as large as few hundred tons for hundreds of miles.
Glaciers move because there is more ice on top: if the movement of glaciers “accelerated” it’s because there is more ice on the higher ground, not because they melt and slide on water. When glaciers melt because of temperature they appear to be retreating, not advancing.
Been a unquestioning warmist myself before the fools started mouthing about glacier discharging into the ocean at “accelerated rates” …
Why? I mean, what’s so significant about this?
What’s next, mapping Buffaloes droppings?
No doubt, for another telephone-number sum, they are gearing up to “discover” that the ice that breaks off the edges move by drifting across the water it floats on. Oh, I seem to have got there first. Any chance of a few million to write it up?
Perhaps if they had looked at this British Antarctic Survey map of Antarctica on Wikipedia, linked from a NASA website created in 2008 this “new” ridge may not have come as such a surprise.
The contours of the greatest heights of ice coincides with this new ridge across several named domes. Isn’t gravity working its magic and causing the ice to flow away from this area a wonder to behold, visualised very nicely in their animation.
Of course if, as remarked on by early comentators above, they truly believe they have discovered something fundamentally new: that ice moves by slipping along the ground it rests on then unfortunately they would be unlikely to have learned anything from looking at such a map.
Dave N says:
August 23, 2011 at 1:51 am
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on”
I’m wondering what else it could possibly be slipping on.. banana peels? Or maybe they were thinking the ground moves with it.. Or it flies through the air?
The previous computer models had the glaciers slipping on ice. The old theory was that it was ice all the way down.
If this is new information, how can they possibly know that there will be “rising sea levels”? It would seem to me more scientifically appropriate to say,”This research will help us understand changes in the rate of ice flow with short-term seasonal changes and long-term changes in climate” or something to that effect. They (as usual) postulate (alleged) CAGW and go from there.
Not science.
At at the other end of the world, a sad note:
Polar Scientist killed in Resolute Bay air crash
http://www.cbc.ca/news/canada/manitoba/story/2011/08/21/mb-north-resolute-bergmann-crash.html?www.mymanitoba.com
Marty Bergmann, director of Natural Resources Canada’s Polar Continental Shelf Program was among the victims in Saturday’s crash of a First Air Boeing 737 that was attempting to land at Resolute Bay in the high Arctic
Quantity of Ice remaining (R) = Initial Amount of ice (I) + Ice Growth (G) – Ice Loss (L). I just made that up and I have never been to University! Can I have a grant please and I will expand on this.
“..including the previously uncharted East Antarctica, which comprises 77 percent of the continent.”
So once again “science is settled” even though they know nothing about 77 % of the largest ice mass on the planet!
as so m,any above were the statement..“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” had me shaking my head..
we went and saw the gouges in the land near the sea in Sth Aus when I was a kid..
maybe this mob used to wag school?
Ian Plimers book had some brilliant descriptions of how ice can be “plastic” with the weight pressing on it..that was new to me. serious science -not dumbed down media crud.
and yeah that ridge also was NOT a new find..
Epic Fail on truth and fact.
Aside from the revelation that glaciers flow on the earth beneath them, I put this in Tips and Notes, albeit not the first, due to the outrageous title Scientific American gave it: Rivers of Melting Ice Mapped in Antarctica . This even with their article making no such reference.
OK, I’ll admit it’s a lovely animation and ignoring the April 1st nature of their supposed discovery lets apply some perspective to this press release.
Comparing the overall km scale bar to the m/yr rate of flow colour bar I see the following:-
From the farthest inland valley ice outflow to the farthest sea edge of the Ross Ice shelf = Up to 1000 years.
From the high centre of the continent to the sea level outflow = Approx 100,000+ years
So it will take the entire time from now to approximately the next interglacial warming for the ice in the middle to make it to the sea….. Therefore there appears to be NOTHING to worry about at all!
Whilst these clever folks are working on it, lets see their animation of total ice accumulation vs loss…. would it perhaps show accumulation inland with a slow gravity assisted slip off the edges? i.e. a dynamic system in action.
Where do I apply for a 7 figure grant to write up my amazing discovery?
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner, NASA’s cryospheric program scientist in Washington.
*groan* This guy can’t be a glaciologist! He obviously doesn’t know what he’s talking about. How glaciers move is part of the tour guide spiel in various national parks that have or were once covered by glaciers. So what’s the requirement to be a “NASA’s cryospheric program scientist”? A PhD in BS?
Seems to me being English based in the UK that NASA seem to spend more time earthbound than space investigating. I suppose ice in space does not move by slipping along the ground so this is the reason the chap is so ebullient about it. He should have asked my children, they know this. Keep spending chaps, new budgets in 6 months.
From the article – “The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner, NASA’s cryospheric program scientist in Washington.
Well that explains a lot about NASA. Most first year geology students learn that, but I guess it took this project to discover something fundamentally new by a cryospheric program scientist.
“Ice moves by slipping along the ground it rests on . . .” is a crock. And it certainly is NOT revealed by computer animation.
Essentially all glacier ice moves by crystal-lattice deformation under the influence of gravity and confining pressure. Ice moves on ice by flowing plastically. And don’t forget phase transformations between different metastable crystal forms of H2O
Remember Silly Putty? Roll it into a ball and leave it on the table top – 30 minutes later, you have a Silly Putty pancake. It did not slip across the table surface. It flowed internally
The “gouging” and “grinding” terms are largely inappropriate as well. Glacial valleys are U-shaped due to freeze-thaw action on cracks in the rocks which acts to pluck material from the valley bottom and include it in the glacial stream. These entrained rocks do the “grinding” that forms glacial striations (e.g.). Ice is never hard enough to gouge anything – except other ice.
sheesh
It appears yet again to be worse than we thought!
BTW, once you understand how glacial ice flows (by persistent crystal-lattice deformation), why should anyone believe that a bubble of gas recovered from an ice core represents a pristine, unaltered sample of the atmosphere at the time of entrapment?
Can anyone explain to a 6-year-old how air gets trapped in polar ice and preserved – unchanged – for 1,000 or 10,000 or 100,000 years, all while that ice is flowing? Without giggling uncontrollably?
It would make a great fairy tale. Perhaps it already is.
The video animation is interesting and is a good visual of the data. Too bad they had to preface it with “The observations provide a better understanding of the flow of Antarctica’s ice sheets, and how they might respond to climate change in the future and contribute to sea-level change.”
http://www.dnr.state.oh.us/parks/parks/lakeerie/kelleys/tabid/18980/Default.aspx
Kelleys Island, in the western basin of Lake Erie, was formed during the glacial period when massive ice sheets from Canada advanced into Ohio • Glaciers gouged and scoured the bedrock, and their tremendous weight left deep depressions which filled with meltwater as the climate warmed and the glaciers retreated, forming the Great Lakes • Evidence of the glaciers can still be seen in the grooves and striations in the island’s limestone bedrock • A large tract of grooves, 15 feet deep and 35 feet wide, has been exposed by an historic quarrying operation, and is believed to be the largest example of glacial striations in the world •
I copied this from the above link. Maybe the folks that go to Antarctica should go here first.
“Like viewers of a completed jigsaw puzzle, the scientists were surprised when they stood back and took in the full picture. They discovered a new ridge splitting the 5.4 million-square-mile (14 million-square-kilometer) landmass from east to west.”
What does “east to west” mean in the context of something centred about the pole?
“The team also found unnamed formations moving up to 800 feet (244 meters) annually”
by comparison, the tip of a six inch long hour hand on a wall clock moves 2,292 feet per year, or 2.86 times faster.
“That’s critical knowledge for predicting future sea level rise. It means that if we lose ice at the coasts from the warming ocean, we open the tap to massive amounts of ice in the interior”
That is not a universally held view. The ice moves at a speed determined by the pressure of the ice pushing it from behind. The resistance of the fringe of ice at the coast is trivial in comparison. It behaves like water spreading out on the surface of a table. by wiping away the drops from the edge of the table, you will not speed up the flow of water from the center. I’ve heard people make this comparison to water in a pipe before, but it is a false analogy in this case. Don’t be lured into this misconception.
Or, to summarise, “Look! Glaciers move!”
Sheesh.
Ice loss has three components: 1) the floating shelf, which by melting doesn’t affect sea-level, 2) the near-shelf areas, and 3) the central source of all ice. So far we are seeing an expansion of the floating shelf and (?) the near-shelf areas are not thinning/losing top altitude. That leaves the central area as shown in the animation.
Although the major ice streams capture the most excitement (and colour) the key to ice loss in Antarctica right now is the centre from whence all ice flows. If that central area is becoming lower (after isostatic rebound!) then Antarctica is losing ice; if it is rising, it is gaining (add in the isostatic sinking!). If the central area is holding steady, Antarctica is holding steady; the increase of ice-shelf area is then a reflection of decreasing annual temperatures and/or decreased wave and tidal action on breaking up the shelf.
So where are the data on Antarctica elevations since 1979? If the roiling seas can be measured to show 3.2 mm/yr growth (almost double tidal gauges), then Antarctica should be a slam dunk. It might even show a 10 mm/yr growth, satellite data being what it is compared to land data.
Very important question to be answered: is the top of Antarctica going up or down? Or is it not being measured ……. inconveniently?
to Jim Cole:
Bravo. It’s amazing how few people understand how ice sheets deform, even though that information is easily obtainable. I have had people argue with me about it, despite showing links to expert explainations of how it works. Whether the ice melts once it reaches the sea it totally irrelevant. The rate of ice loss due to calving of icebergs is many times greater than melting anyway. The melting just makes for smaller icebergs.
What does “NASA” stand for again? How is watching ice flows related to aeronautics and space exploration? It’s like NATO being misused for Middle East regime change, instead of being a Western European self-defense treaty.
Bloke down the pub
August 23, 2011 at 1:17 am
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner”
Fundamentally new? WTF? If this guy is not being misquoted then he has definitely led a very sheltered life.
###
Thomas Wagner is probably no scientist, and defiantly had nothing to do with this study. He is in DC.which means that he is most likely a management flunky that w as selected by the Press Release author because he would give the correct “Were All Gona Die” response to the leading question.
Thomas Cole: Agree. And anybody who looks at a glacier (with its stress fractures and its toffee-like entrainments of rubble) will get an intuition that reflects the underlying mechanism. I would love to see some science done (or literature on what has been done) regarding the conditions at the bedrock/glacier interface. Obviously very high pressure, so does that mean a boundary layer of melt-water (like a hydroplaning tire)? With a slurry of rocks large and small to act as a kind of “grinding paste”? Presumably any given rock gets dragged along, scraping the basement layer of rock at X feet/year until it’s been reduced to dust. Why is this not well-understood by NASA sound-biters?
Also agree that the dynamics for the continent as whole are powered by the mass/height gradient from the inner highlands to the outer edges. Like a pyramid of ice cream or, as some commenters have said, Silly Putty. The faster the flow at the edge, the more stuff must have fallen at the center. Not sure what the lag time in system would be: if it stops snowing today, when does the pressure ease off the field enough to reduce the flow rate at the edge?
Thomas Cole: one more thing. I am no physicist but I would speculate that the velocity field for the ice (vertical axis) is not uniform. At the top, there is least pressure so it is just carried along. At bottom, it is “sticking” on the underlying rock and the boundary velocity by definition is zero. The peak velocity is presumbly somewhere in the column, where the plasticity of the ice is maximized due to vertical pressure and the downslope velocity is maximized due to upslope mass. Doing a 3-D velocity field would be very, very useful. Maybe NASA can spend its next budget cycle giving us that.
““The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner, NASA’s cryospheric program scientist in Washington.”
My daddy told me that when I was about twelve years old and wondered why the gouges in the rocks all went in the same direction. Apparently he should have been a cryospheric program scientist rather than a carpenter!
As a matter of fact glacier ice moves both through interior deformation and by “slipping along the ground”. Which mechanism predominates depends mostly on the temperature at the bottom of the ice-sheet.
OMG, I can visualize the ocean lapping at the bottom of our driveway any day now–and we’re nearly 200 m above sea level!
Oh wait! Beachfront property!
Andy_E says:
August 23, 2011 at 3:27 am
“Isn’t gravity working its magic and causing the ice to flow away from this area a wonder to behold, visualised very nicely in their animation”
Nope, that can’t be it. That’s like saying the Earth is warmed by the Sun. It’s just wrong!
oMan says:
August 23, 2011 at 10:58 am (Edit)
Thomas Cole: Agree. And anybody who looks at a glacier (with its stress fractures and its toffee-like entrainments of rubble) will get an intuition that reflects the underlying mechanism. I would love to see some science done (or literature on what has been done) regarding the conditions at the bedrock/glacier interface. Obviously very high pressure, so does that mean a boundary layer of melt-water (like a hydroplaning tire)? With a slurry of rocks large and small to act as a kind of “grinding paste”? Presumably any given rock gets dragged along, scraping the basement layer of rock at X feet/year until it’s been reduced to dust. Why is this not well-understood by NASA sound-biters? …
oMan says:
August 23, 2011 at 11:03 am (Edit)
Thomas Cole: one more thing. I am no physicist but I would speculate that the velocity field for the ice (vertical axis) is not uniform. At the top, there is least pressure so it is just carried along. At bottom, it is “sticking” on the underlying rock and the boundary velocity by definition is zero. The peak velocity is presumably somewhere in the column, where the plasticity of the ice is maximized due to vertical pressure and the downslope velocity is maximized due to upslope mass. Doing a 3-D velocity field would be very, very useful. Maybe NASA can spend its next budget cycle giving us that.
Well, yes. That is what they do. More accurately, that (3D modeling of the flow, and assuming the edges of the glacier – the U-shaped trench where the ice rubs against the rock wall – is what they try to do.
But … Big “but” here.
When you read the glacier textbooks, you find that they “assume” a simple curved wall. Trenches, holes, dips, “valleys” and natural bumps, dips, and humps in the wall are ignored. (They’re too hard to calculate, and are “mushed” into a single, easy-to-calculate coefficient.
Then, making the assumptions worse and the relationships less accurate – They “assume” that single friction component between ice and wall is true and valid and constant at all points of contact. From valley tip to top of valley, from head to tail of the glacier, they assume a single coefficient, and most often – a single constant slope of the valley from top to bottom. (Some functions allow the “valley” to spread out as it get further down, but most also assume a single valley contour from top to bottom.)
From all of these simplifying assumptions, they then develop a single integrated equation relating glacier speed and glacier length to “top of mountain” ice deposit rates at various melt rates (valley base temperatures).
Now, many, many texts and web sites go on to discuss “water accelerated flow” – or use equal words to describe a rare phenomena where glacier accelerate at irregular intervals as they “skid” across melted water underneath. All greatly more feared by CAGW theories, of course.
What these fears feed on is ignorance of the “bottom” of real glacier valleys, exaggeration by the proponents of glacier acceleration – who need to spread this fear – and simple lubrication facts:
Liquid Water under the glacier is needed to act as the lubricant. If the valley is non-uniform by even a few feet across the base of the valley – as all valleys are by dozens of feet in between actual mountains – then the water cannot build up without being squished by the ice pressure AROUND the obstructions and holes and humps and rises. As it squishes around obstructions on the floor, the obstructing “keys” are still dry, and the ice still locked up from movement.
Lubrication theory – as of a near-perfectly machined high speed shaft turning inside a near-perfectly machined bearing at high speed – requires a very smooth surface uniformly shaped that builds up a triangle-shaped wedge of high-pressure oil injected inside the bearing in a uniformly smooth wide area. The shaft rides up on this wedge, and friction is reduced substantially compared to dry sliding.
But … these perfectly machined shafts and the smooth bearings have no slots and no grooves that allow the oil to flow out of the wedge. The shaft is turning at many hundreds of feet per second – compared to a glacier at hundreds of feet per year! The water under a glacier cannot build up into a wedge because it cannot easily trapped under the ice into a uniform thickness. When the water gets trapped at one location under a glacier, it rises up, then flows out and around the obstruction and further down the valley. As it flows, the water will be concentrated into a small area on the valley floor – the very little “V” at the bottom. Widely spread water is opposed by both the glacier mass above – which will tend to force the water away from high spots and away from the mass of the glacier, and the gravity force trying to keep the water just in the very bottom of the valley. That is, the glacier pushing down will prevent water from flowing uphill and under the ice anywhere but the very middle of the valley.
Also, this liquid water must be under substantial fractions of the area under the glacier: so, as the melt water spreads out – and it does spread out – it must be pushed up the walls of the valley, where it is even easier to flow in the grooves and openings between the side of the ice and the wall of the valley since the wall pressure of ice to wall reduces as you go up the valley walls. To build up enough water under the ice to create the lubricating wedge of liquid, you need almost a square-corner valley where the water gets trapped on a mostly flat bottom and can raise (float) the ice sufficiently.
Only rarely will enough water build up on a smooth enough valley section to cover the whole bottom deep enough to allow movement. And, of course, as actual glacier movements goes, accelerated/lubricated flow is very, very rare compared to the tens of thousands of glaciers worldwide.
Thanks, RA;
I would imagine that detailed examination of the data just retrieved will show the fallacy of the “sliding” metaphor.
I also note that “solid” rock also flows and deforms under pressure, given enough time. Take a look at the curved and wavy strata exposed on mountain tops some time! Ice is orders more plastic, and flows and twists far more readily.
About the “hang-ups”: IIRC that acceleration of the Western ice shelf and more rapid calving was eventually traced to the breaking of a deep barrier ridge of rock that had held it back for millennia.
“The map points out something fundamentally new: that ice moves by slipping along the ground it rests on,” said Thomas Wagner, NASA’s cryospheric program scientist in Washington. “That’s critical knowledge for predicting future sea level rise. It means that if we lose ice at the coasts from the warming ocean, we open the tap to massive amounts of ice in the interior.”
An open minded person would ask what fundamental change in understanding has the occurred in the research. Instead the regulars posting to this site look only to bolster their bias, pat each other on the back strutting around like roosters in the hen yards.
What this work does do is give us base line. If in the future ice flows speed up we will know because NASA has been watching
The Antarctic glaciers have been doing this for 33.5 million years (perhaps 42 million years at the high-elevation accumulation peaks).
Even when the Earth’s average temperature was 4.0C higher in the Miocene.
So, it is a great map, but it does not lead one to believe that the glaciers can melt out (until Antarctica moves off the South Pole through continental drift).
It now appears that NASA is suddenly paying more attention to sea level rise as a result of mass contribution (glacial melt, water runoff) as opposed to thermal expansion. Today NASA made a press release pointing to excessive precipitation over certain continents as a reason for the 1/4 inch drop in sea level over the last year. The map appears to show Northern Antarctica gaining mass at the expense of sea level. They blame La Nina.
http://www.jpl.nasa.gov/news/news.cfm?release=2011-262
Be sure to note the logarithmic color scale.
The first animation implements ~uniform crawling speed for all segments moving between 10m/year1000m/year. I guess this is to indicate direction, but is vastly misleading with regard to speed.
The second portion of the animation seems to display proportional speeds; only the pink and red segments >1000m/year show motion, and the red moves faster than the pink.
Bill Illis says:
August 23, 2011 at 5:16 pm
The Antarctic glaciers have been doing this for 33.5 million years (perhaps 42 million years at the high-elevation accumulation peaks).
Even when the Earth’s average temperature was 4.0C higher in the Miocene.
The Antarctic is for the most part a gigantic frozen desert. The conventional wisdom seems to be that precipitation rates, in other than the coastal periphery, are in the range of 4 to 8 inches per year. What records we have suggest that, in most interior areas, it never is now and likely, because of the elevations involved, never has been warm enough at any season of the year to melt that precipitation. At six inches per year, which at the temperatures involved represents many feet of snow, you are talking about adding 6000 inches every thousand years, a nice round 500 feet or 500,000 feet every million years. About 100 miles
In general, I’ve never had much confidence in the ice core data, but as I recall they don’t show enough variation to suggest that the never actually warm enough to melt ice state has changed much over all those millenia. Antarctica is presently covered by about a mile of ice on average which, my BOTE calculation suggests, means that some significant multiple of 100 miles of ice thickness has extruded out into the seas over the years. I would point out that that thickness is averaged over an area that is close to twice the area of the lower 48 US states, a number that is just about matched by the seasonal max to min of the surrounding sea ice.
In isolation the various numbers bandied about for the loss of ice in Antarctic always seem dramatic, but considered in context they are like a flea on an elephant.
This may have drifted a bit off topic by now, but let me restate my question from August 23, 2011 at 7:38 am
Why does anyone believe that air bubbles preserved in ice cores (at great depth/pressure) bear any resemblance to the atmospheric chemistry/isotopic ratios at the time of capture/inclusion?
By what series of processes does ambient air get “trapped” as a bubble inclusion in ice?
Sure, the gas chemistry/isotopics in the bubbles represent SOMETHING, but WTF??
I’m open to any rational explanation – but fairy tales seem to prevail.
Mark Thomas @ 8:07 a.m. “What does “east to west” mean in the context of something centred about the pole?”
Even though Antarctica is at the pole, part of Antarctica is in the Eastern Hemisphere, part in the Western Hemisphere. This also happens to roughly (not precisely, but roughly) correspond to the natural division of Antarctica by the massive mountain range that acts as the border along a major portion of the primary ice cap. Due to the differing terrain and physical features, it is quite common to refer to either Eastern or Western Antarctica.
I agree, that is a great question. For a comparison, up in Greenland at Summit there is increasing height …
http://stevengoddard.wordpress.com/2011/08/16/ice-sheet-getting-thicker-as-it-catastrophically-thins/
I cannot find a reference now but I remember seeing that the depth near the south pole was two mile thick ice from top to the ground level. That is a lot of weight so there must always be some compacting going on, not to mention pressing of the Earth itself into the mantle below causing a decrease of elevation.
So as a counter to this one would expect there to be added snow on the top end or else the AGW drama queens would be yelling at the top of their lungs about vanishing glaciers in Antarctica. We always hear that the Antarctic is a super dry desert and it rarely snows because the humidity is zero. In my mind that sounds like and water vapor that makes it down to the Antarctic immediately falls out of the air as ice or snow (how else were miles of ice were formed!), so the air must be completely dry AFTER the water falls out.
Place a GPS system on the surface (there must be hundreds if not thousands now) and tell us what is the elevation, going up or down? Are things placed on Antarctica covered in snow and ice after a period of time or not?
So your question is excellent, particularly the “Or is it not being measured ……. inconveniently?“.
To those discussing glacier height changes – along with ice plasticity, flow, and the issues of how accurate ice core data is or isn’t… or heck, for anyone else interested – don’t forget the Glacier Girl and the Lost Squadron!!
Everytime I hear how rapidly Greenland is losing ice, or for that matter almost any large scale glacier or ice issue, Glacier Girl immediately pops into mind. How can there be massive ice loss, when she wound up buried 268 ft deep in only 50 years??!! And she’d drifted over a mile from her original location to boot. Plasticity, flow… if you get that in 50 years, how do they accurately deal with such issues for ice core info? I know, I know, all of this could be a number of things like localized increase w/ overall decreases, or some weird glacier dynamic I’m unaware of that turns the surface under and drags it down (but then she wouldn’t have been intact I would think)…
Amazes me that they not only recovered her, but flew her again! It really is an incredible story.
And it certainly highlights a number of technical issues associated with glaciers.
http://p38assn.org/glacier-girl.htm
@ Jim Cole says: August 23, 2011 at 8:38 pm
Jim, a paper you might be interested in that I just ran across a few days ago is: Atmospheric CO2 fluctuations during the last millennium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles Lenny Kouwenberg, et. al 2005
I admit I’ve been skeptical of ice core results for a long time also, but am fully aware that may be due to my own ignorance. I’ve read a number of papers on the issue, but have no idea how much weight those who propose (in the peer reviewed literature or by those who are qualified scientists in the area) actually holds… of course then sites like rc or skepticalscience poo poo any question of their validity making it difficult for one not in the field to tell just what does or doesn’t have real merit. So I wind up tucking my skepticism back into a corner of my mind again and evaluate again whenver I run across more info.
Frankly, it seems to me that until we can get ice cores calibrated both in terms of actually measured CO2 levels, temperatures, AND ice depth, there’s really no way to know how accurate the ice core data is. Obviously that’s not going to happen for a very long time, e.g., we’d have to see how the Mao Launa (sp?) CO2 data we’ve actually measured, starting when, about the 1950’s? compares to ice core data that was from the same timeframes, after it’s firned, then at various depths as time went on to see just how much changes over time in pressure, temperature, water chemistry, crystallization, (including what biological contamination might occur from the time the air becomes trapped all the way until the final ice core is taken too!) etc., etc., how all of these factors affects the finaly resulting data. We’ll all be long long dead and gone by the time they’re able to compare our 1950-2000 CO2 measurements to ice that’s been in place for hundreds, then thousands of years.
Anyhow, the paper above touches on your very issue – that the ‘firn’ process whereby ice bubbles finally become permanently (?) trapped may lead to ice core results that can’t be resolved any closer than several decades, or even centuries – e.g. shifts in CO2 levels such as we’re currently seeing may be lost in the wash so to speak.
Here’s a more generalized article: http://www.geocraft.com/WVFossils/stomata.html
and it references Zbigniew Jaworowski’s work – which I gather the warmists claim is bunk… his work and logic sounds fine to me, and if correct would make a huge difference – but then what do I know? http://www.john-daly.com/zjiceco2.htm
Anyhow, I would be interested in anything you turn up along these lines – or any light folks here can shed on the merits of Jaworowski’s work, plus related supporting or debunking research.
Oops, my bad. Here’s where you can find the stomatal frequency paper online: http://docs.google.com/viewer?a=v&q=cache:xs5srOHXGBkJ:fm1.fieldmuseum.org/aa/Files/lkouwenberg/Kouwenberg_et_al_2005_Geology.pdf+atmospheric+co2+fluctuations+during+the+last+millennium+reconstructed+by+stomatal&hl=en&gl=us&pid=bl&srcid=ADGEEShppZmaPk_h02vpSDys0Uo6fhPYWHV-epA7Plbwobpc6vdAmEz28wTOdKOhsq0Q2SyOT8BtMogG8mJEjdDSvwp4TCb3cx7m_oOFOTwRLgI1UbW-c1etIp9HFfakE4yMZKACYdJg&sig=AHIEtbTubDQITdGD6B9zhEH95VviEc9uBA