East Antarctic Ice Sheet has stayed frozen for 14 million years

December 15, 2015 by Katherine Unger Baillie, University of Pennsylvania
The field site in East Antarctica, which has been frozen for more than 14 million years.

Antarctica was once a balmier place, lush with plants and lakes. Figuring out just how long the continent has been a barren, cold desert of ice can give clues as to how Antarctica responded to the effects of past climates and can perhaps also indicate what to expect there in the future as Earth's atmospheric concentration of carbon dioxide grows.

In a new study in Scientific Reports, University of Pennsylvania researchers use an innovative technique to date one of Antarctica's ancient lake deposits. They found that the deposits have remained frozen for at least the last 14 million years, suggesting that the surrounding region, the East Antarctic Ice Sheet, or EAIS, has likewise remained intact.

The work adds new support for the idea that the EAIS did not experience significant melting even during the Pliocene, a period from 3 to 5 million years ago, when concentrations rivaled what they are today.

"The Pliocene is sometimes thought to be an analog to what Earth will be like if continues," said Jane K. Willenbring, an assistant professor in the Department of Earth and Environmental Science in Penn's School of Arts & Sciences. "This gives us some hope that the East Antarctic Ice Sheet could be stable in today's and future climate conditions."

Willenbring collaborated on the study with lead author and Penn graduate student Rachel D. Valletta, as well as Adam R. Lewis and Allan C. Ashworth from the University of North Dakota and Marc Caffee from Purdue University.

Current climate change projections indicate that the marine portion of the West Antarctic Ice Sheet is "a goner," Willenbring said. Studies from the past few years suggest that sea level will likely rise a few meters as that ice melts. But the East Antarctic Ice Sheet is 20 times more massive. If it melted, the ensuing sea level rise would be even more catastrophic than the western peninsula's dissolution.

Fossils of leaves and other organisms associated with warmer climates reflect the area's balmier past.

To shed light on what could happen in the future to the EAIS, geologists often look to the past. But there is not a scientific consensus about how the EAIS has behaved in different climates throughout history. Some scientists believe the experienced significant melting during the relatively warmer conditions of the Pliocene, while others think it has remained almost entirely frozen for the last 14 million years.

Willenbring and colleagues hoped to help clarify the history of the EAIS. They traveled to Antarctica's Friis Hills in the central Dry Valleys of the eastern portion of the continent. About a foot beneath the surface are sediment deposits from an ancient lake which is known from animal fossils to have been freshwater. Earlier dating established that the volcanic ash deposits at the bottom of the ancient lake are 20 million years old.

To see if any melting had occurred in the interim, they analyzed radioactive isotopes of beryllium known as beryllium-10, which form in the atmosphere when cosmic rays collide with oxygen and nitrogen atoms.

"Beryllium-10 sticks on to particles quite easily and is associated with lake deposits," Willenbring said. "We wanted to see if we could use this isotope to figure out how long the sediment was in place and isolated from liquid water."

Beryllium-10 has a known half-life of 1.4 million years. After estimating an initial level of initial concentration of beryllium-10 in their lake samples, the researchers were able to estimate the age of the sediments to be between 14 and 17.5 million years ago.

"We found that the beryllium-10 was almost completely gone, within the resolution of our technique," Willenbring said.

Willenbring said the team was confident that the area had remained frozen since then because if there had been melting, the water would have penetrated the sediments and "reset" the beryllium-10 measurements.

"This means that the sediment is definitely older than the time when a lot of people think that Antarctica might have been quite deglaciated," she said.

By offering support for the idea that the EAIS has been largely stable during the last 14 million years, the research offers some hope that a massive collapse of the ice sheet, and associated rise of tens of meters, may not be imminent.

Willenbring, however, cautions that even though carbon dioxide levels in the Pliocene may be analogous to today's levels, the two situations are not equivalent and thus any conclusions can only be taken so far.

"Even though the Pliocene conditions could be an analog for CO2 concentrations today, we've probably never experienced such a fast transition to warm temperatures as we're seeing right now," she said.

Explore further: Research reveals the reality of runaway ice loss in Antarctica

More information: Rachel D. Valletta et al. Extreme decay of meteoric beryllium-10 as a proxy for persistent aridity, Scientific Reports (2015). DOI: 10.1038/srep17813

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1.3 / 5 (12) Dec 15, 2015
I wonder how they can explain the Piri Reis Antarctica map?
4.6 / 5 (10) Dec 15, 2015
"As far as the accuracy of depiction of the supposed Antarctic coast is concerned, there are two conspicuous errors. First, it is shown hundreds of miles north of its proper location; second, the Drake Passage is completely missing, with the Antarctic Peninsula presumably conflated with the Argentine coast. The identification of this area of the map with the frigid Antarctic coast is also difficult to reconcile with the notes on the map which describe the region as having a warm climate."

There is no reason to include the Pri Reis map, it didn't include Antarctica, despite the claims of
Erich von Däniken and other idiots.
1.5 / 5 (8) Dec 16, 2015
The maps do not have to be completely accurate in order to have been drawn by humans. That's not a strong argument, and there have indeed been specialist mapmakers who have validated their validity. In fact, there are unusual correspondences for a Greenland map as well.

Further, and perhaps more problematic, is the issue of the Eocene tropicality which is not refutable -- and neither explainable by any shifting from plate tectonics. Fact is that there used to be alligators and crocodiles at the North Pole, as well as trees hundreds of feet tall. This is a huge problem because neither should be able to survive the months of darkness we see today in the winter months (crocodiles sink and drown, believe it or not, below 65 F!). The Eocene tropicality remains a mystery -- one which was brought up in the recent Senate hearings by Mr Steyn, and which was completely ignored by the global warming advocate on hand.
1.5 / 5 (8) Dec 16, 2015
"drawn by humans of this particular area ..."
5 / 5 (11) Dec 16, 2015
On the one hand: several layers of scientific evidence supporting a hypothesis (that Antarctica's ice is older than humans).

On the other, one map, which is disputable at best as to what it represents.

I think I'll take science, and chalk up the map to artful fancies of the past.

Hannes: Believe it or not, there are *extinct* species of trees and crocodiles. Different species can inhabit different environmental conditions, depending on what they're adapted to. No one's saying that the Florida American Alligator was crawling around in Alaska.
4.6 / 5 (9) Dec 16, 2015
The Eocene tropicality remains a mystery -- one which was brought up in the recent Senate hearings by Mr Steyn, and which was completely ignored by the global warming advocate on hand.

It is not a mystery.
4.2 / 5 (10) Dec 16, 2015
Have you ever looked at the Piri Reis map? It's quite evident that its author simply ran out of room at the bottom of the map when drawing South America's east coast, and continued drawing it by bending everything south of Rio de Janeiro to the right. If you want to pretend that rightward extension is actually Antarctica, you either have to ignore the fact that it is physically connected to the rest of a peculiarly truncated South America, or you pretend that there was a land bridge between South American and Antarctica at the same time that the Antarctic ice had melted and raised the sea levels. You might was well throw aliens and Atlantis into the discussion at that point.
Captain Stumpy
5 / 5 (6) Dec 17, 2015
Fact is that there used to be alligators and crocodiles at the North Pole
at the north pole?


did the Russians find the skeletons under all that ice?
or was it an American sub trawling and mapping?
or were the skeletons IN the ice?
is that how you know alligators sink in cooler weather? [hyperbole]

could you please show some sources?
(not pseudoscience links, but reputable peer reviewed journal studies, thanks)

i'm not even going to mention the whole extinct species to you, since shavera covered it, and you will ignore it
3.7 / 5 (6) Dec 17, 2015
I dunno', there may be something to this alligator in the North Pole thing.

It doesn't mention what kind of animals lived in Polar Forests (which I have found annoying, since a lot of them say there were animals, but no source I found named them beyond "mammals were rare").
4.3 / 5 (6) Dec 17, 2015
@Captain Stumpy

During the early Eocene there were indeed alligators above the Arctic circle but the climate was considerably warmer. That was not the North Pole however.

3.7 / 5 (6) Dec 17, 2015
Thanks for the link, Vietvet! I am finding these polar forests to be really cool.

A new study of the High Arctic climate roughly 50 million years ago led by the University of Colorado at Boulder helps to explain how ancient alligators and giant tortoises were able to thrive on Ellesmere Island well above the Arctic Circle, even as they endured six months of darkness each year.

Time travelers get all the best research grants.
Captain Stumpy
5 / 5 (7) Dec 18, 2015
I dunno', there may be something to this alligator in the North Pole thing
During the early Eocene there were indeed alligators above the Arctic circle but the climate was considerably warmer. That was not the North Pole however
Sorry... i should have explained
hannes made a statement that he called a "fact"
Fact is that there used to be alligators and crocodiles at the North Pole
Now, whereas i can see there is some evidence for it by yall's studies and links (and others)...
there has been absolutely zero fossil evidence dug out of the ground at the current North Pole because it is under ice and ocean

it can be a guess
it can be surmised
it can be logically extrapolated based upon other evidence
it can be hypothesized
and it can be said to be probable

but it can't be said to be a "fact" without being able to actually get to the ground to unearth fossils

sorry for the confusion guys
4.2 / 5 (5) Dec 18, 2015
My bad.

I read North Pole and thought Arctica. With 1,300 miles of ice covered ocean between Ellesmere Island and the North Pole the only alligators to be found would in a very bad scifi novel.
Captain Stumpy
5 / 5 (4) Dec 18, 2015
My bad
I read North Pole and thought Arctica
yeah... figured as much
no prob

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