West Antarctic ice shelf breaking up from the inside out

November 28, 2016 by Pam Frost Gorder
Rift in Pine Island Glacier ice shelf, West Antarctica, photographed from the air during a NASA Operation IceBridge survey flight on Nov. 4, 2016. This rift is the second to form in the center of the ice shelf in the past three years. The first resulted in an iceberg that broke off in 2015. Credit: Credit NASA/Nathan Kurtz.

A key glacier in Antarctica is breaking apart from the inside out, suggesting that the ocean is weakening ice on the edges of the continent.

The Pine Island Glacier, part of the ice shelf that bounds the West Antarctic Ice Sheet, is one of two glaciers that researchers believe are most likely to undergo rapid retreat, bringing more ice from the interior of the to the ocean, where its melting would flood coastlines around the world.

A nearly 225-square-mile iceberg broke off from the glacier in 2015, but it wasn't until Ohio State University researchers were testing some new image-processing software that they noticed something strange in satellite images taken before the event.

In the images, they saw evidence that a rift formed at the very base of the ice shelf nearly 20 miles inland in 2013. The rift propagated upward over two years, until it broke through the ice surface and set the iceberg adrift over 12 days in late July and early August 2015.

They report their discovery in the journal Geophysical Research Letters.

"It's generally accepted that it's no longer a question of whether the West Antarctic Ice Sheet will melt, it's a question of when," said study leader Ian Howat, associate professor of earth sciences at Ohio State. "This kind of rifting behavior provides another mechanism for rapid retreat of these glaciers, adding to the probability that we may see significant collapse of West Antarctica in our lifetimes."

While this is the first time researchers have witnessed a deep subsurface rift opening within Antarctic ice, they have seen similar breakups in the Greenland Ice Sheet—in spots where ocean water has seeped inland along the bedrock and begun to melt the ice from underneath.

Howat said the provide the first strong evidence that these large Antarctic ice shelves respond to changes at their ocean edge in a similar way as observed in Greenland.

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In 2015, a 225-square-mile iceberg broke off of the Pine Island Glacier in Antarctica, and researchers at The Ohio State University have discovered that the event was no ordinary breakup. The culprit: a deep subsurface rift that cracked through the ice nearly 20 miles inland--a sign that the largest ice reserve in the world may be melting sooner rather than later. Credit: Series of Sentinel-1A satellite images courtesy of Seongsu Jeong, The Ohio State University.

"Rifts usually form at the margins of an ice shelf, where the ice is thin and subject to shearing that rips it apart," he explained. "However, this latest event in the Pine Island Glacier was due to a rift that originated from the center of the ice shelf and propagated out to the margins. This implies that something weakened the center of the ice shelf, with the most likely explanation being a crevasse melted out at the bedrock level by a warming ocean."

Another clue: The rift opened in the bottom of a "valley" in the ice shelf where the ice had thinned compared to the surrounding ice shelf.

The valley is likely a sign of something researchers have long suspected: Because the bottom of the West Antarctic Ice Sheet lies below sea level, ocean water can intrude far inland and remain unseen. New valleys forming on the surface would be one outward sign that ice was melting away far below.

The origin of the rift in the Pine Island Glacier would have gone unseen, too, except that the Landsat 8 images Howat and his team were analyzing happened to be taken when the sun was low in the sky. Long shadows cast across the ice drew the team's attention to the valley that had formed there.

"The really troubling thing is that there are many of these valleys further up-glacier," Howat added. "If they are actually sites of weakness that are prone to rifting, we could potentially see more accelerated ice loss in Antarctica."

More than half of the world's fresh water is frozen in Antarctica. The Pine Island Glacier and its nearby twin, the Thwaites Glacier, sit at the outer edge of one of the most active ice streams on the continent. Like corks in a bottle, they block the ice flow and keep nearly 10 percent of the West Antarctic Ice Sheet from draining into the sea.

Studies have suggested that the West Antarctic Ice Sheet is particularly unstable, and could collapse within the next 100 years. The collapse would lead to a sea-level rise of nearly 10 feet, which would engulf major U.S. cities such as New York and Miami and displace 150 million people living on coasts worldwide.

"We need to understand exactly how these valleys and rifts form, and what they mean for stability," Howat said. "We're limited in what information we can get from space, so this will mean targeting air and field campaigns to collect more detailed observations. The U.S. and the U.K. are partnering on a large field science program targeted at that area of Antarctica, so this will provide another piece to the puzzle."

Explore further: New study reveals when West Antarctica's largest glacier started retreating

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18 comments

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gkam
3 / 5 (12) Nov 28, 2016
Do the Deniers care? Do they assume we are all liars, looking for research funding?

Does that shine a light on their character and not of the scientists?
antigoracle
2 / 5 (8) Nov 28, 2016
More fodder for the ignorant Chicken Littles.
https://www.googl...othermal
TheGhostofOtto1923
3.7 / 5 (6) Nov 28, 2016
Do the Deniers care? Do they assume we are all liars
You are a liar. We already know that.
looking for research funding?
Are you pretending to be a scientist now george??
Does that shine a light on their character and not of the scientists?
Confirmed liars do not make very good advocates for any cause. George kamburoff has trashed his character here.
cjones1
1.8 / 5 (10) Nov 28, 2016
The magnetic South pole is drifting away from West Antarctica according to recent measurements. That makes sense when they talk about more snow and ice accumulating in East Antarctica. I remember that there are active tectonic and volcanic regions in West Antarctica. I am not familiar with the warm ocean currents that may affect West Antarctica. The AGW proponents seem very quick to deny other scientific causes of ice loss in West Antarctica.
There are ancient maps that have mapped Antarctica's coastlines. Modern science had little idea of the coastlines until after WW II.
We can seed clouds and make rain. We can make deserts bloom and clear cut forests. There is no doubt that humans can terraform and affect local weather, but the AGW/CO2 folks have narrowed their perspective and condemned scientific debate with a near religious fervor.
Paulw789
1.6 / 5 (12) Nov 29, 2016
This is a fast-moving glacier that pushes out to the sea. Every few years, another chunk breaks off and is replaced by the glacial flow from behind.

This is what glaciers do. Why does every ice-berg imply some type of disaster. There are thousands of them every year from Antarctica
gkam
2.6 / 5 (10) Nov 29, 2016
The Deniers say it is okay, and when the sea level rises too far, it is because the environmentalists did it to hurt us.

They got it from Trump, the Scientist.
raykelly1940
1 / 5 (8) Dec 02, 2016
I think the scientists have got their sums wrong, most of the ice is already floating in the sea, therefore it is already displacing its own weight anyway, only ice that comes from snow which falls on land may contribute to a rise in sea levels, but where did the water come from that formed the snow? the sea of course, it's not rocket science is it? Ray Kelly1940
TheGhostofOtto1923
4.4 / 5 (7) Dec 02, 2016
I think the scientists have got their sums wrong, most of the ice is already floating in the sea, therefore it is already displacing its own weight anyway, only ice that comes from snow which falls on land may contribute to a rise in sea levels, but where did the water come from that formed the snow? the sea of course, it's not rocket science is it? Ray Kelly1940
Hey ray, what makes you think that professionals who have spent their lives studying these things haven't included that knowledge in their conclusions? And what makes you think that they would have occurred to someone like yourself after reading a news article for 2 minutes and not to pros who put many weeks of work into their study?

And what makes you think that posting under your real name and DOB would make you any less prone to ridicule for such opinions?

Don't feel bad - that's a common mistake around here.
gkam
1 / 5 (7) Dec 02, 2016
raykelly, welcome to the world of internet snipers. "otto" is one. He brags how he uses variations of that name in his pseudonyms, playing what he described as his "games" here. He is crude, verbally violent, and nasty.

I suggest if you want to stay that you do not refer or respond to him.
antigoracle
1.8 / 5 (5) Dec 02, 2016
raykelly, welcome to the world of internet snipers. "otto" is one. He brags how he uses variations of that name in his pseudonyms, playing what he described as his "games" here. He is crude, verbally violent, and nasty.

I suggest if you want to stay that you do not refer or respond to him.

raykelly, for your sake, please take a wide berth from gskam. He is a pathological liar who trolls this forum looking for unsuspecting victims. He has actually boasted how his lies can't hurt him, but they can most definitely hurt you. Don't accept nor divulge any personal information with him.
gkam
1 / 5 (6) Dec 02, 2016
ray, I am George Kamburoff, in California. I identified myself because I am a retired professional, known by name. All of my work was from word-of-mouth, personal recommendations, and all professionals I know have no need for anonymity.

But the snipers here will follow you. They ("Uncle Ira"), put the URL of the picture of one guy's house so they could make fun of it. Otto is known for screaming disgusting words in ALL CAPS. antigore is stuck on calling everybody "retard". Real class.

I think they have no real lives outside of the phony one.
antigoracle
1 / 5 (4) Dec 02, 2016
ray, I am George Kamburoff, in California. I identified myself because I am a retired professional, known by name. All of my work was from word-of-mouth, personal recommendations, and all professionals I know have no need for anonymity.

But the snipers here will follow you. They ("Uncle Ira"), put the URL of the picture of one guy's house so they could make fun of it. Otto is known for screaming disgusting words in ALL CAPS.

I think they have no real lives outside of the phony one.

@ray.
And, so it begins, the pathological lies.
Ask gskam, how many on this forum he has threatened to sue and why?
Uncle Ira
4.6 / 5 (9) Dec 02, 2016
They ("Uncle Ira"), put the URL of the picture of one guy's house so they could make fun of it.
You still telling that lie Cher? It never happened, just like a lot of those "REAL" engineer jobs you really did not have.

Oh yeah, I almost forget. That Skippy you are giving the welcome and advice for? He been here five year more than you have.
gkam
1 / 5 (5) Dec 02, 2016
See?
Phys1
5 / 5 (5) Dec 02, 2016
I think the scientists have got their sums wrong, most of the ice is already floating in the sea, therefore it is already displacing its own weight anyway,

I think I heard that before, about 2250 years ago.
antigoracle
1 / 5 (5) Dec 02, 2016
I think the scientists have got their sums wrong, most of the ice is already floating in the sea, therefore it is already displacing its own weight anyway,

I think I heard that before, about 2250 years ago.

Another gem from the Retard of the Decade.
Phys1
5 / 5 (6) Dec 03, 2016
I think the scientists have got their sums wrong, most of the ice is already floating in the sea, therefore it is already displacing its own weight anyway,

I think I heard that before, about 2250 years ago.

Another gem from the Retard of the Decade.

So lunaticle never heard about Archimedes.
Phys1
4.4 / 5 (7) Dec 03, 2016
raykelly, for your sake, please take a wide berth from gskam.

Also, avoid insanicle. He's a mouthfoaming antiscience agitator.

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