From the University of Texas at Austin
New map reveals giant fjords beneath East Antarctic ice sheet
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.
The map reveals some of the largest fjords or ice cut channels on Earth, providing important insights into the history of ice in Antarctica. The data will also help computer modelers improve their simulations of the past and future Antarctic ice sheet and its potential impact on global sea level.
“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.
“We chose to focus on the Aurora Subglacial Basin because it may represent the weak underbelly of the East Antarctic Ice Sheet, the largest remaining body of ice and potential source of sea-level rise on Earth,” said Donald Blankenship, principal investigator for the ICECAP project, a multinational collaboration using airborne geophysical instruments to study the ice sheet.
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. Indeed, this work shows that the ice sheet has been significantly smaller in the past.
Previous work based on ocean sediments and computer models indicates the East Antarctic Ice Sheet grew and shrank widely and frequently, from about 34 to 14 million years ago, causing sea level to fluctuate by 200 feet . Since then, it has been comparatively stable, causing sea-level fluctuations of less that 50 feet. The new map reveals vast channels cut through mountain ranges by ancient glaciers that mark the edge of the ice sheet at different times in the past, sometimes hundreds of kilometers from its current edge.
“We’re seeing what the ice sheet looked like at a time when Earth was much warmer than today,” said Young. “Back then it was very dynamic, with significant surface melting. Recently, the ice sheet has been better behaved.”
However, recent lowering of major glaciers near the edge detected by satellites has raised concerns about this sector of Antarctica.
Young said past configurations of the ice sheet give a sense of how it might look in the future, although he doesn’t foresee it shrinking as dramatically in the next 100 years. Still, even a small change in this massive ice sheet could have a significant effect on sea level. Scientists at The University of Texas at Austin’s Institute for Computational Engineering and Sciences, and at Australia’s Antarctic Climate and Ecosystems CRC are developing models that will use the new map to forecast how the ice sheet will evolve in the future and how it might affect sea level.
This research is part of ICECAP (Investigating the Cryospheric Evolution of the Central Antarctic Plate), a joint project of The University of Texas at Austin’s Jackson School of Geosciences, the University of Edinburgh and the Australian Antarctic Division. 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.
Funding for this research is provided by the National Science Foundation (U.S.), the National Aeronautics and Space Administration (U.S.), the Natural Environment Research Council (U.K.), the Australian Antarctic Division, the G. Unger Vetlesen Foundation (U.S.), the Antarctic Climate and Ecosystems CRC (Aus.), and the University of Texas at Austin’s Jackson School of Geosciences (U.S.).
A gallery of images is available at: http://www.jsg.utexas.edu/galleries/antarcticice060111/
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Keith Minto says:
June 1, 2011 at 11:14 pm
“They deserve a medal for bravery for flying a DC-3 in that environment. What a great workhorse.”
Keith,
I suspect they were flying a ‘zero timed, stretched and strengthened’ DC-3 airframe, retrofitted with modern turboprop engines (“Polar 5” or “Polar 6”). These wonderful old Douglas birds are ‘remanufactured’ to far better than new, at Basler Aircraft LLC, in Oshkosh WI, specifically for rugged ‘back country’ work!
Oshkosh is also home to the single largest aviation conference, airshows, and aviation fly-ins in the world: The Experimental Aircraft Association (EAA) annual AirVenture! It’s the greatest aviation lalapalooza on earth, during the last week of July each year. Oshkosh is to aviation fans what mecca is to the muslims! Here’s a couple of links, for those similarly afflicted as I!
Basler Turbo Conversions, LLC Basler Turbo 67 Aircraft
http://www.baslerturbo.com/
Experimental Aircraft Association
http://www.eaa.org/
http://www.airventure.org/
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.
I wonder if they saw any inclusions in the ice like old airplanes, Noah’s Ark, giant flying saucers crashed 10,000 years ago, or old Coors Beer cans? I wonder if they saw any inactive volcanos under there that might erupt and cause a problem? Maybe Jimmie Hoffa is in there somewhere?
Just thinking outside the box and trying to make the weekend more fun.
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.
Mac the Knife says:
June 3, 2011 at 10:29 am ,
Thanks for that information and the links, fascinating. Looking at the photos later, yes, they looked like turboprop engines but I had no idea that the DC3’s were being remade to close to their original design. I spent a lot of time in these in outback NSW in earlier times, in the days when going up and sitting and chatting with the pilot was OK.
“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?
Some sea level computations.
http://pathstoknowledge.net/2009/02/22/a-sea-level-calculator
http://pathstoknowledge.net/2009/02/22/how-could-we-melt-enough-ice-for-a-20ft-rise-in-sea-levels
lets see the ice become “lubricated” with melt water and “slip” of those puppies!
Very interesting set of conversations! I would like to add the thought of a positive feed back loop.
If for one unit of sea level rise there occurs 10 units of flooding or coast line recession along thousands of miles of mile thick glacier, would this not increase dramatically the rate of sea level change? I found the ICECAP article by looking for a topo-map of Antarctica that would show how the feed back loop i envisioned could or could not happen. I think it would be good if we could figure out the possibilities.