Radar mapping reveals ancient Antarctic giant fjords

While some of the valleys look like they could have been carved by glaciers the overall terrain must have been rapidly covered (draped?) by stable ice to retain its sharp relief.

For three field seasons, the team flew an upgraded World War II-era DC-3 aircraft with a suite of geophysical instruments to study the ice and underlying rock in East Antarctica.

They deserve a medal for bravery for flying a DC-3 in that environment. What a great workhorse.

OK. This is seriously interesting. I love it.

Michael Schaefer says: (June 1, 2011 at 10:37 pm)
How a portion of ice that’s already under water…
If Michael’s point concerns this paragraph in the paper, Anthony (“Because the basin lies kilometers below sea level, seawater could penetrate beneath the ice, causing portions of the ice sheet to collapse and float off to sea.”) it is a valid question it would be interesting to see answered. I do not think floating and land based point apply. The ice noted is below sea level.

Typo:
Since then, it has been comparatively stable,
stabile

What a load of more CAGW bullcrap! You need only look at the sponsers of said project(?) to see the Warmistas hand at play again.
And where is the evidence for their sea level rise figures? And just how much GHG does a DC-3 produce???

Because of the difference in density between liquid water and ice, 90% of an iceberg is below water. If more than 10% of the glacier is above sea level, then the sea cannot penetrate below the ice due to the excess weight forcing it out. If the bottom is “kilometers” below sea level, that means the glacier must be several hundred meters above sea level to stay grounded. The radar image shown indicates the surface of the glacier is between 2 and 3 kilometers above sea level.
Why are we worried at all? The basin bottom would have to be at least 20 to 30 kilometers deep to float that ice. The thinnest part shown on the right side of the figure is only 2 km above sea level. The basin bottom appears to be about 1.5 km deep at most.

So it is 2500 meters above the water line, and 1500 meters below water line (max), and only in the “blue dots”. How exactly is this piece of ice supposed to float? Bloody fearmongering.

Interesting study with helpful enlargements. That part or Antarctica ‘released’ Australia about 50mya and there is a match with the Great Australian Bight. Those fjords are shaped to be slipping into that ‘sea’, another rock profile is here.
ICECAP ? ….. rings a bell……..:)

Are they suggesting the climate has changed in the past in quite dramatic ways? Is there any radar trace of the ancient SUVs that caused that?

I assume, for the seawater to get in under the ice, the water pressure would have to be greater than the ice-pressure and that would depend on how much the ice is above sea level…

A few comments on this post.
Rock surface levels would rise if the ice melted due to isostatic adjustment. This would take several thousands of years.
The ffiord indicated is more likely a river valley given the distortion imposed by the height expansion compared to range. Ffiords ratio of depth to width are different to that of river valleys which are wider than the depth.
This graphic is never the less a good example of real climate change not the couple of degrees that the alarmists are scared about which lies within natural variation of weather in any case.

Despite the arguments re ice floating etc that are being raised, for my money it is a welcome report that actually quantifies the true ice extent and if their interpretations are correct, how much used to be there. Makes a nice change from the “assumed” extent that is so often used as definitive data. Th more hard data we have , the better.

If the land were to rise there, it would sink somewhere else, so the effect would possibly be local. Depends where the “somewhere else” is, I suppose — and whether it’s linked to the oceans.

So, did they find any Nazi artifacts under the ice at Neuschwabenland? Adm. Byrd went looking in 1946, but something ran him off….

Galane says: June 2, 2011 at 12:03 am :

Now for the really puzzling bit, if that basin is below sea level *now*, how did the terrain get all carved up by ice in the warmer distant past?

You’ve asked the right question.
The continent we call Antarctica wasn’t always home to the “south” pole.
Over the eons, thanks to “continental drift” the Antarctic land mass
migrated to the location we find it now, relative to the other continents,
ocean basins, and spreading centers.
See the article by Campbell Craddock, “Antarctic Geology and Gondwanaland”,
from the December, 1970, Bulletin of the Atomic Scientists at:
http://books.google.com/books?id=EAcAAAAAMBAJ&pg=PA2&lpg=PA2&dq=Polar+migration+++continental+drift+Antarctic&source=bl&ots=cecy92RTQT&sig=OnjT9LgVrg-6J9lSy3j_7lmWGNI&hl=en&ei=2WnnTcqgIMaRgQfPwLjzCg&sa=X&oi=book_result&ct=result&resnum=2&ved=0CCEQ6AEwAQ#v=onepage&q=Polar%20migration%20%20%20continental%20drift%20Antarctic&f=false
This was written long before changes in climate became synonymous with
politically charged anthropomorphically influenced temperature or
climate shifts.
As the continent drifted into it’s current bottom-of-the-world position, it
gradually “froze”. The gradual build up of the ice over the ensuing
millennia physically depressed the land beneath it.
If you look at the above radar “map” at around the 290 kilometer mark,
there’s a “saddle” or “Twin Peaks” formation that is, I recall from a glaciology
class long ago, a classic signature of once-active aggressive glaciation.
(Don’t forget that little gotcha in the upper right corner of the map… 50 x
vertical exaggeration make for a startling virtual snapshot. )
If you’ll scroll down a bit after the Craddock piece, there are a couple
more articles that seem germane to threads running here on WUWT.

It seems that large continental ice sheets do eventually push a land mass far enough below sea level that the oceans can seep in and break-up the glaciers.
There is probably no issue with this given the extent and height of the current Antarctic ice sheet but I am surprised at how far below sea level some of these areas in Antarctica are.
Land depression, ocean moving in and breaking-up the glaciers has happened before when north Africa was at the South Pole and to southern South America when it was at the south pole. It seems to have happened every 5 Mys during the Carboniferous ice age given the sea level changes which occurred.
Hudson Bay is really just a depression caused by the peak load point of the glaciers during the ice ages. Look at Google maps and see how much of the continental shelf of north Europe and north Asia extends out into the Arctic ocean. It seems to me that at some point in the last last 1.5 Mys, this area was all above sea level, became significantly glaciated, the land was pushed below sea level and now there is only ocean there (except in the height of ice ages when the glaciers push back out into the Arctic ocean).
Antarctica melted back to less than 1/4 of its present size between 27 and 14 Mys ago. May be this was part of it.

Isn’t it a tad bit odd to to reference climate 34-14 million years ago in antarctica like antarctica was situated where it is now? Antarctica wasn’t really located in antarctica back the when grand dad was that young. If I understand it right, that piece of land has had the gall to move quite a bit since then.
So why would the climate 34 million years ago be interesting in comparison to today.

Anybody ever done a study on continental drift and it’s affect on climate history of the earth?
This is very interesting and brings up another question for you guys. All these modelers focus on the components of green house gases but what about the biggest component and it’s distribution over geologic time? That would be water.
What would happen to the planet if there were no clouds? What would happen to the planet if there was 100% cloud cover? After all we have a planet that is 70% oceans. Has it ever been 90% ocean or 50% ocean? What affects would land mass vs ocean coverage have on climate?
I think we spend too much money researching CO2 and other gases when we ignore the most common one H2O.
If the oceans start rising maybe it would be cheaper to just build a pipeline to the south pole and spray sea water out over the icecap and make ice there by offsetting the melting if any. Kind of like the ski areas do.

Jack Green says:
June 2, 2011 at 8:23 am
“Anybody ever done a study on continental drift and it’s affect on climate history of the earth? ”
Saw a History Channel or Science Channel or some such channel that posed a theory that “snowball earth” was caused by continental drift blocking the ocean conveyor that brings warm waters north.

“We knew almost nothing about what was going on, or could go on, under this part of the ice sheet and now we’ve opened it up and made it real,” said Duncan Young, research scientist at The University of Texas at Austin’s Institute for Geophysics and lead author on the study, which appears in this week’s journal Nature.
====
“There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”
Mark Twain
But, it’s a start 🙂

Consider a homogeneous slab (2-D) of ice. Archimedes principle says:
—If floating ice melts, water level does not change.
—If ice is anchored and it melts above the waterline, runoff will raise the water level.
-The underlying land can respond to the runoff by moving either up or down depending on whether the ice is buoyant, which depends on how much ice is above the waterline and how much is below (which can depend on how the ice is attached to the land).
—The land’s response depends as well on its own mechanical properties and how its own mass is supported.
—How the waterline (water level referenced to the land) changes is indeterminate without further information. A change in waterline will also change the buoyancy of any ice in contact with both water and the land (feedback).
Consider two simple ‘bedrock’ cases – fixed land (no moving or stretching) with ice on top and surrounding water.
1 – If the ice above water is massive enough, ice will weigh down on the bedrock. If ice above water melts, the ice weight (on the bedrock) will drop and the amount of water will increase (water level rises). This is the conventional GW scenario for ice melting and sea levels rising. However, in this same scenario, if submerged ice melts, the opposite happens – sea level drops and ice weight increases.
2 – If ice is in some way attached (freezing?) to the bedrock and too little is above water, it will be buoyant (pull upward). As before above-water melting increases the water level and underwater melting decreases it. But now above-water melting increases (and below-water melting decreases) buoyancy.
Even in such oversimplified examples, the case for GW melting and rising water levels is not leakproof. To be more realistic, the examples have to be expanded to allow ice and land to vary in horizontal directions. Then the mechanical responses of both become important – loading local ice does not affect distant ice beyond some distance ‘characteristic’ of the ice, so notions of loading and buoyancy must be expanded
Overall, even these simple models based only on first principles exhibit complex behavior. In reality, of course, there are other things that bear on the outcome – the response of the land and how melting at the ice-land boundary is affected by pressure, to name but two. Sea level response (and therefore the global drowning bogeyman) is also complex, the more so because remote parts of the ocean are also involved.

Bold added:
Scientists from the U.S., U.K. and Australia have used ice-penetrating radar to create the first high- resolution topographic map of one of the last uncharted regions of Earth, the Aurora Subglacial Basin, an immense ice-buried lowland in East Antarctica larger than Texas.
I wasn’t aware of the ocean basins being charted all that well, let alone at a high resolution. When we were discussing the March 2011 Japan Earthquake and I was researching the differing terms hypocenter and epicenter to figure out what was meant by “…the hypocenter at an underwater depth of approximately 32 km (20 mi)…” (From sea level or sea floor?), I found there was a relative paucity of depth soundings for what should be a well-studied geographically important area around Japan.
Have we really charted the ocean basins well enough to justify the “one of the last” statement and its implication the total job is nearly done, or is the writer just being land-centric?

“Because the basin lies kilometers below sea level, seawater could penetrate beneath the ice, causing portions of the ice sheet to collapse and float off to sea.”
This can only happen under very special conditions. Since glacier ice is about 80-90% as dense as sea-water more than this proportion of the ice thickness at the coast must be below sea-level. Furthermore the depth to bedrock must continuously increase inland in order for the sea-water to be able to continue penetrating further inland under ever thicher ice. As far as I can see from the map this is not the case in this area. There is a sill of bedrock along the coast, so this is actually a glacier lying in a depression, the most stable type there is.
“a holmes says:
June 2, 2011 at 11:27 am
The antarctic ice must be an enormous store of the intense cold in the winters , so how come seawater close to freezing but still liquid is able to trickle into the area below sea level without being frozen solid immediately it encounters the ultra cold ice ?”
The ice at the bottom of the ice-cap is not “ultra cold”. It is close to melting due to geothermic heat and high pressure. A couple of kilometers of ice is pretty good insulation.
“1DandyTroll says:
June 2, 2011 at 6:52 am
Isn’t it a tad bit odd to to reference climate 34-14 million years ago in antarctica like antarctica was situated where it is now? Antarctica wasn’t really located in antarctica back the when grand dad was that young. If I understand it right, that piece of land has had the gall to move quite a bit since then.
So why would the climate 34 million years ago be interesting in comparison to today.”
Sorry, but no. Antarctica has been fairly stationary near the South Pole since long before 34 million years ago.
“Geoff Sherrington says:
June 2, 2011 at 6:05 am
Have you ever wondered what the climate and geography were like some 700,000 years ago if that is the correct age of the Vostok ice core hole? It seems to have ended close to a rock basement.
Was there no ice there 700,000 years ago? Is all the ice that is there now younger than 700,000 years? Are there any disconformities in the ice core, showing precious melting or erosion? Has the earlier basal ice (if any) been squeezed laterally away to the sea, there to melt? Has anyone found older ice being squeezed sideways into the sea in the Antarctic?”
Yes, the earlier ice has been squeezed laterally away to melt. Deep ice cores are taken at “ice divides” where sideways motion is zero, but ice divides move around with changing climate so it is probably difficult to find places where much older ice can be found even close to rock basement. Also there is basal melt in some areas which removes the oldest ice. Finding the old ice being squeezed into the sea is a tad difficult since it is all happening many hundred meters below sea level.
However there is a chance of finding really old ice in Antarctica in the so called “blue ice areas”. Blue ice is old deep ice that has been blocked from moving by getting stuck against a mountain and is just lying there very slowly sublimating away. The oldest blue ice found up till now is about 500 000 years old, but in principle it can be as old as the present icecap, i e about 15 million years.

u.k.(us) says:
June 2, 2011 at 12:23 pm
““We knew almost nothing about what was going on, or could go on, under this part of the ice sheet and now we’ve opened it up and made it real,” said Duncan Young, research scientist at The University of Texas at Austin’s Institute for Geophysics and lead author on the study, which appears in this week’s journal Nature.
====
“There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”
Mark Twain
But, it’s a start :)”
It’s all of the “Iceholes” that cause these problems, in the ice sheet, that is. Lord knows there are plenty of them.

Irrespective of temperatures, I would expect that glaciers if, indeed, resting on the bottom and not floating would continue to carve the fjords and those pictured need not be so old. Pressure creates its own lubricant for glaciers and if there is a slope they would conyinue on their merry way down hill.

“The only ice that can raise sea levels if it melts is ice that is both 1. above sea level and 2. not floating. Floating ice has a net zero effect on sea level when it melts because it’s displacing 100% of its mass and volume in water already.”
Given the accuracy of that,
(1) What is the Total Volume all naturally occurring ice on Planet Earth?
(2) What volume of the Total Volume of ice is floating in water?
(3) What volume of the Total Volume of ice is sitting on the sea floor?
(4) What volume of the Total Volume of ice is on land?
How much will the oceans rise given the melting of each of these?

lets see the ice become “lubricated” with melt water and “slip” of those puppies!