Environment

Giant cavity found eating away at Antarctic glacier from underneath

Giant cavity found eating away...
Thwaites Glacier in West Antarctica
Thwaites Glacier in West Antarctica
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Thwaites Glacier in West Antarctica
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Thwaites Glacier in West Antarctica
A map showing changes in topography at Thwaites Glacier, between 2011 and 2017. Red areas indicate the highest rate of sinking, with the section in the middle representing the newly-found giant cavity, and the bottom-left corner showing extensive calving
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A map showing changes in topography at Thwaites Glacier, between 2011 and 2017. Red areas indicate the highest rate of sinking, with the section in the middle representing the newly-found giant cavity, and the bottom-left corner showing extensive calving

Glaciers are kind of an endangered species in our rapidly-warming world, and unfortunately scientists keep finding new threats to them. NASA's ongoing Operation IceBridge has now found a gigantic cavity underneath Thwaites Glacier in West Antarctica, which shows that the area has suffered even more drastic ice loss in recent years than previously thought – and it's accelerating.

Thwaites Glacier is roughly the size of Florida, and by itself reportedly holds enough ice to raise the global sea level by 2.1 ft (65 cm). Worse still, it stands between the warming waters and neighboring glaciers, so if it goes others are expected to follow soon enough.

That makes Thwaites an important target for study. As part of Operation IceBridge, specialized planes fly over the frozen continent a few times a year and take radar readings of the ice below. The radar could peer through the ice and examine how much ice had been lost underneath.

Although it was expected that some ice loss had occurred, the team was surprised to see exactly how much was missing. The radar revealed a cavity measuring almost 1,000 ft (300 m) tall underneath Thwaites Glacier, big enough to have once contained 14 billion tons of ice. The majority of that had melted away in just three years.

"We have suspected for years that Thwaites was not tightly attached to the bedrock beneath it," says Eric Rignot, co-author of the study. "Thanks to a new generation of satellites, we can finally see the detail."

Located on the western side of Thwaites Glacier, the cavity was created as warmer waters lapped at the bottom of the glacier over the years, and unfortunately, it's a vicious cycle. The more the hole grows, the more ice is exposed to water, which speeds up the melting. This pushes the grounding line – where the ice meets the bedrock below – further and further inland, destabilizing the glacier.

A map showing changes in topography at Thwaites Glacier, between 2011 and 2017. Red areas indicate the highest rate of sinking, with the section in the middle representing the newly-found giant cavity, and the bottom-left corner showing extensive calving
A map showing changes in topography at Thwaites Glacier, between 2011 and 2017. Red areas indicate the highest rate of sinking, with the section in the middle representing the newly-found giant cavity, and the bottom-left corner showing extensive calving

Data shows that between 1992 and 2017, the grounding line on the western side of Thwaites Glacier has been retreating at a steady rate of between 0.4 and 0.5 mi (0.6 to 0.8 km) per year. The situation is worse on the eastern side, where the retreat rate has doubled – from 0.4 mi (0.6 km) per year between 1992 and 2011, to 0.8 mi (1.2 km) per year between 2011 and 2017.

Strangely enough, even though the retreat rate is worse on the eastern front, the melt rate is higher on the western side of the glacier. The researchers aren't sure why that is, but it does go to show that interactions between the ice and the ocean are much more complex than previously thought.

The International Thwaites Glacier Collaboration is preparing to embark on a field study on the ground during the Southern Hemisphere's next summer, in late 2019 and early 2020. The researchers on the current study hope that these new results will help inform that team's work.

"Such data is essential for field parties to focus on areas where the action is, because the grounding line is retreating rapidly with complex spatial patterns," says Pietro Milillo, lead author of the study.

The research was published in the journal Science Advances.

Source: NASA JPL

9 comments
D_trigger2113
Glaciers are so endangered out of the seven that we used to have there are only 7! and considering ice flows down and we still don't fully know how much snow fall there is per year and how they are replenished, its a good thing you're here to inform the scientific community and us lay people that we are running out of glaciers.
skepsci
Look at this glacier on earth. It is well along the process of calving. It is what glaciers do. I am interested to see the last 2000 years of progress it has been making on this process. With that perspective it will be possible to see the value oe intent of this piece.
F. Tuijn
Large parts of the Thwaites glacier are floating so melting that will not raise the level of the oceans.
Mr T
I love all the "educated" comments from joe averages who have such a great understanding of the complex interactions and processes taking place, despite not having a second of education in these fields. It's no wonder things are not improving, if this is the level of intelligence of the average person.
christopher
Its impossible to trust a single word that comes out of a climate-alarmist scientist's mouth. To start with, floating ice displaces the same volume of water when melted, so all the bits not on ground will have no effect on sea levels. As for the land - the glacier (floating and grounded combined) is 264m high, 170,305km^2 in area, and our seas are 361,100,000km^2 in area - so do the math - there's not a snowballs chance in Antarctica that even if the entire thing melted, it could have even the same order of magnitude difference to sea levels than all the alarmists claim. And that not even starting on the bleeding obvious - there's not a licking bit of difference humanity can make to the direction of our climate, no matter how much you love numbers. 80 million new humans per year and our insatiable need to cook, move around, and reproduce are going to annihilate everything you *think* you might be able to do to "make a difference". Someone needs to start a "name and shame" site for idiot greenies, so that anytime a new one fails to do their basic sums, they get blacklisted and are never allowed to publish again. There is zero disincentive for those idiots to not bullshit their asses off, and 99% of the population have no clue just how full of crap they are. The world is bad enough to just stick to the truth - we don't need more fake crap adding weight to the opposition.
john.s
"The common misconception that floating ice won’t increase sea level when it melts occurs because the difference in density between fresh water and salt water is not taken into consideration." https://nsidc.org/news/newsroom/20050801_floatingice.html
ljaques
OH, LOOK! What does it mean? UH, I DON'T HAVE A CLUE. When the chunk of Larsen C broke off in July of 2017, the headlines showed "surprise", even though they had seen the start of it in 2012, over FIVE years earlier. Then it took scientists eight months to go see what was under it, at which time anything under it would be dead and/or gone, and the headlines shows that scientists had "quickly" gone to see it. This is only more of the wailing by people seeking more funding for their search into the scam we know as AGWK. <yawn> The audacity of "scientists" who claim knowledge of the sciences around this event is enormous. They even admitted that they don't know what it means, yet they scream for money and attention. Ye Gods. They also don't tell you that as ice recedes from one side of the continent it grows a similar amount on the other side of the continent. Do they discuss the balance? NO. Christopher is right. The alarmists cannot be trusted on anything. Algore lied. Michael "hockey stick" Mann lied. NASA lied. NOAA lied. East Anglia CRU lied/data-nudged, etc. and bad data is included in IPCC findings, so they lied. Bjorn Lomborg walked away from Greenpeace and the Left because of their constant lies. The 1998 book is called _the Skeptical environmentalist: Measuring the Real State of the World_. It's never ending. Yes, our climate is changing, as we're almost halfway between ice ages. The sun is much more guilty of causing this change than man, so there is nothing to do about it but plan for change. Taking us back to the stone age won't cut it. Another question: Did these researchers happen to look under the ice to see if any new volcanoes were there, just very =possibly= affecting ice depth? I didn't think so. Mr. T, if the scientists know it all, why do they continue to find new data points to add to their climate modeling software -every- year, decade after decade? Some of us Average Joes have read dozens of books on the subject because it interests us. What's your story? Just another Average Joe who -=Believes=- in the Church of Global Warming?
Observer101
Mother Nature doing her thing! Could it BE, the heat from the earth beneath is melting the ice from beneath? NAHHHHHH!
RobertTaylor
We are going to keep increasing the flights over the glacier and increase the amount of radar imaging of the glacier until we figure out why it is melting, DUH!!!!!!!!!!!!!