National Geographic News
Photo of an Adelie penguin atop a block of melting in East Antarctica.

An Adelie penguin stands atop a block of melting ice in East Antarctica.

PHOTOGRAPH BY PAULINE ASKIN, REUTERS

Larry O'Hanlon

for National Geographic

Published May 4, 2014

Small plugs in the coastal ice shelves of East Antarctica are all that are holding back several meters of sea level rise worldwide, according to a pair of climate researchers.

However, it would take centuries of exposure to waters warmer than currently exist for such a situation to occur, they report today in Nature Climate Change.

If all the ice sheets of Antarctica melted, they would raise sea level by 60 meters (200 feet). Even with anthropogenic climate change, there's little chance that will happen. But a rise even a fraction of that amount would be devastating.

Scientists are beginning to understand the dynamics of the marine ice of West Antarctica, but less so that of East Antarctica, where there's enough frozen water to raise sea level 53 meters (174 feet). The new study focused on one part of East Antarctica, the bowl-like Wilkes Basin, which sits below sea level and holds enough ice to raise sea levels 3 to 4 meters (10 to 13 feet).

An ice sheet isn't static. Ice is added from the land and ice exits into the sea by melting and calving of icebergs. If these two amounts are equal, the ice sheet can be said to be in "balance," with its mass staying about the same from year to year.

Matthias Mengel and Anders Levermann of the Potsdam Institute for Climate Impact Research in Germany simulated what would happen if the ocean warmed enough to "imbalance" the Wilkes Basin ice shelf, tinkering with both the ice input and output. In particular, they tested what would happen if they increased the ice losses to the sea without any more inflow from the land.

When they did this, the researchers discovered that there is a zone of ice near the seaward end of the ice shelf that is wedged against ridges of rock. These wedges of ice acted like a plug for the entire shelf.

If that narrow ice plug were to melt, the ice shelf would become unstable and disintegrate. The ice currently held within the basin would flow into the ocean and raise global sea level by several meters.

"This is unstoppable when the plug is removed," said Levermann. "The speed [of removal] we don't know, but it's definitely a threshold."

A Distant Threat

In the simulation, the ice shelf retreated a bit from the sea at the beginning, but the situation was not irreversible. When the ice plug threshold was crossed, however, the melting continued, and the ice shelf disintegrated.

The ice plug effect "was a little twist that was surprising in our simulation," Levermann said. Such a situation is plausible, however; a similar scenario seems to be playing out at the much smaller West Antarctic Pine Island Glacier, which lost its plug when it broke free of its seafloor ridge in the 1970s and is already contributing to sea level rise.

Ice plugs in East Antarctica might also explain why massive amounts of ice were able to melt and raise the oceans to levels much higher than those seen today during the very warm late Pliocene, 4.8 to 3.5 million years ago.

There is no danger of the Wilkes Basin emptying itself of ice anytime soon, though. Mengel and Levermann's simulations involved scenarios of 400 to 800 years and waters 1 to 2.5°C warmer than today.

"They are also talking about temperatures much higher than they are now," said Ian Joughin of the University of Washington's Polar Science Center in Seattle. While it's true that in some places, such as at the small Pine Island Glacier, warmer water is moving in and melting smaller ice shelves, larger ice shelves are harder to melt.

"Big ice shelves have quite a lot of cold water under them," said Joughin. "In West Antarctica, a lot of times the winds have changed and pulled warm water in." In East Antarctica there are also warmer waters offshore. But those waters would require a few thousand years to eat away enough East Antarctic ice to endanger the ice plugs and the entire ice shelves, he said.

"This is fairly good news," Joughin said, because it means the huge reserve of ice in the Wilkes Basin won't be melting anytime soon. However, he noted, "it might be a huge problem a thousand years from now."

6 comments
Paul Schott
Paul Schott


Is it too late to do something Father?
 

Father look another fish near the top of the water Young Eagle soon there will be many as the water goes down.
Father and when the water is gone what will we eat Young Eagle that is foretold in Revelation 19:17-18
Have no fear young Eagle, those who are faithful to our Father in Heaven to the end will be saved.



Father and the wicked and lost Young Eagle Most of them will die in the desert because they did not believe
and were not faithful as did more then 3,000 years ago.



Satan's Sin City “Las Vegas” very soon to die like a fish out of water.



World Leaders Pay Close "ATTENTION". KJV Rev 11:18



This Planet Earth Cannot And Will Not Support Life As We Know It Without Its FOREST.
Soon all will take note to the sounds and rumbling of Volcanoes and Earthquakes Around Earth that are Waking Up at a Alarming Rate.
Just as they did in 1883 from Krakatoa.



LEADERS PLANT TREES WHILE YOU STILL CAN.



Read well and study on your own after you have read this.



This is not a game or joke our Sun gives off a Solar Wind all day year round. If you live in the State of Alaska you see it in the
sky above what a sight it is going through our Earth’s Magnet Polls of the North and the South, North Poll. It’s called the
Northern Lights or the Aurora Borealis. The day will come when you will be able to see it all over Earth as in the year 1859 Solar Flare,
It was the largest in 500 years. Two Astronomer’s Hodgson and Carrington told the World that the Solar Flare made a Geomagnetic
Storm reach Earth in hours not days. Back then it gave new meaning to "Reach For The Skies" from Telegraph Operators.
For hours sparks flew from the key board. Even after the Batteries were disconnected. Nov 3 and 4, 2003 had a X40+ Class Solar Flare,
Thank GOD it was not coming at Earth this time.

Sarah Dowdy
Sarah Dowdy

Sounds like Miami is gonna be a real life Atlantis in about 1,000 years

Justin Smith
Justin Smith

NG needs to change their name to Doom and Gloom.  

Steven Wyatt
Steven Wyatt

The only real question is how long do we have as people refuse to change their ways.

Jack Wolf
Jack Wolf

Well, if New York, Miami, and Norfolk want to be around for long, they better start figuring out how to put a cork in the bottle.  Now it will take a small cork, later a much bigger one.

Craig Dupras
Craig Dupras

Just because its going to take 400 to 800 years from now to melt doesn't mean that we shouldn't take it seriously right now. These are what our future generations will be facing. The real problem is that every problem is always related to the oil. Pollution and the fact that there is too much resistance from oil companies for people to actually do something about it 

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