West Antarctic ice melt could raise seas by three meters

This photo provided by NASA on June 13, 2013 shows the ice front of Venable Ice Shelf, West Antarctica
This photo provided by NASA on June 13, 2013 shows the ice front of Venable Ice Shelf, West Antarctica

Melting ice in West Antarctica is a major concern for global sea levels, and a key area may already be unstable enough to unleash three meters of ocean rise, scientists said Monday.

The study follows research out last year, led by NASA glaciologist Eric Rignot, warning that ice in the Antarctic had gone into a state of irreversible retreat, that the melting was considered "unstoppable" and could raise by 1.2 meters (four feet).

This time, researchers at Germany's Potsdam Institute for Climate Impact Research pointed to the long-term impacts of the crucial Amundsen Sea sector of West Antarctica, which they said "has most likely been destabilized."

While previous studies "examined the short-term future evolution of this region, here we take the next step and simulate the long-term evolution of the whole West Antarctic Ice Sheet," the authors said in the Proceedings of the National Academy of Sciences.

They used computer models to project the effects of 60 more years of melting at the current rate.

This "would drive the West Antarctic Ice sheet past a critical threshold beyond which a complete, long-term disintegration would occur."

In other words, "the entire marine will discharge into the ocean, causing a global sea-level rise of about three meters," the authors wrote.

"If the destabilization has begun, a three-meter increase in sea level over the next several centuries to millennia may be unavoidable."

Even just a few decades of ocean warming can unleash a melting spree that lasts for hundreds to thousands of years.

"Once the ice masses get perturbed, which is what is happening today, they respond in a non-linear way: there is a relatively sudden breakdown of stability after a long period during which little change can be found," said lead author Johannes Feldmann.

Large uncertainty

The authors noted that Antarctica's situation presents the largest uncertainty in sea level projections for the coming centuries, and that studying the vast region poses many challenges.

And indeed, just days before the PNAS study was released, another scientific paper used NASA satellite data form 2003 to 2008 to show that Antarctic ice had gained mass, and had packed on enough to exceed the amount lost in other areas.

"We're essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica," said a statement by Jay Zwally, a glaciologist with NASA Goddard Space Flight Center whose study was published October 30 in the Journal of Glaciology.

"Our main disagreement is for East Antarctica and the interior of West Antarctica—there, we see an ice gain that exceeds the losses in the other areas."

According to climatologist Michael Mann, who was not involved in either study, the use of older satellite data could be the cause for the disconnect.

"It sounds to me as if the key issue here is that the claims are based on seven-year-old data, and so cannot address the finding that Antarctic ice loss has accelerated in more recent years," he told AFP.


Explore further

Local destabilization can cause complete loss of West Antarctica's ice masses

Journal information: Journal of Glaciology

© 2015 AFP

Citation: West Antarctic ice melt could raise seas by three meters (2015, November 2) retrieved 23 May 2019 from https://phys.org/news/2015-11-west-antarctic-ice-seas-meters.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
1035 shares

Feedback to editors

User comments

Nov 02, 2015
Sounds like the moving business just became the best future career choice. We're humans. We'll adapt. But we need to get off this rock. Go NASA go.

Nov 02, 2015
Sounds like the moving business just became the best future career choice. We're humans. We'll adapt. But we need to get off this rock. Go NASA go.

Nov 02, 2015
In other words, "the entire marine ice sheet will discharge into the ocean, causing a global sea-level rise of about three meters," the authors wrote.


This is often repeated but is not reasonable. The marine ice sheet is already in the ocean. It can break off or melt with no increase in sea-level rise.

Nov 02, 2015
Dogbreath said:
In other words, "the entire marine ice sheet will discharge into the ocean, causing a global sea-level rise of about three meters," the authors wrote.


This is often repeated but is not reasonable. The marine ice sheet is already in the ocean. It can break off or melt with no increase in sea-level rise.


Ice sheet, not Ice shelf. The shelf floats. The sheet is on land. You are wrong, the ice sheet is not already in the ocean. The ice shelf is.

Nov 02, 2015
Facts are not needed when promoting global climate change

Nov 02, 2015
thermodynamics,
Ice sheet, not Ice shelf. The shelf floats. The sheet is on land.


It doesn't matter if you call it a sheet or a shelf. The author is plainly talking about ice that is in the water. He uses the term "marine ice". Land ice is not marine ice. Here is the quote again:

In other words, "the entire marine ice sheet will discharge into the ocean, causing a global sea-level rise of about three meters," the authors wrote.

Nov 02, 2015
Our main disagreement is for East Antarctica and the interior of West Antarctica—there, we see an ice gain that exceeds the losses in the other areas.

Oh, the mysteries of GloBULL warming, ice increasing everywhere but where there is extensive geothermal activity.

Nov 02, 2015
thermodynamics,
Ice sheet, not Ice shelf. The shelf floats. The sheet is on land.


It doesn't matter if you call it a sheet or a shelf. The author is plainly talking about ice that is in the water. He uses the term "marine ice". Land ice is not marine ice. Here is the quote again:

In other words, "the entire marine ice sheet will discharge into the ocean, causing a global sea-level rise of about three meters," the authors wrote.


Dogbreath makes it clear he is just making up his own definitions. It doesn't matter to him that there are technical definitions for ice shelves, ice sheets, and even marine ice. And, instead of just saying - oh, I mistyped, he doubled down by trying to say it doesn't matter. Technical terms and critical reading are important to understanding science.

Nov 02, 2015
Thermo, as you seem to know a bit about the subject perhaps you could lay off bagging the dog and explain some details.

As the base of the marine ice is below sea level, would there not be a point of equilibrium? Such that if the melting continues then lakes form? I'm not clear how the melting ice sheet seems to run uphill to form ice shelves.

Yes I tried to find an answer myself but most sources just seem to wander off into warming consequences.

Nov 02, 2015
Ah .. I see this mentioned in another thread and is more complicated than I expected.

Nov 02, 2015
It doesn't matter if you call it a sheet or a shelf.  -- dogbert
False.

Ice sheet: "is a chunk of glacier ice that covers the land surrounding it and is greater than 50,000 kilometers (20,000 miles) wide. An ice sheet is also known as a continental glacier."

Ice caps: "cover less than 50,000 square kilometers and usually feed a series of glaciers around its edges. While not hemmed in by any surface features (they lie on top of mountains), they are usually centered on a highest point (called a massif)."

Ice shelf: "is a thick, floating slab of ice that forms where a glacier or ice flows down a coastline."

Quotes from here: http://ete.cet.ed...cesheets

Nov 02, 2015
Thermo, as you seem to know a bit about the subject perhaps you could lay off bagging the dog and explain some details.

As the base of the marine ice is below sea level, would there not be a point of equilibrium? Such that if the melting continues then lakes form? I'm not clear how the melting ice sheet seems to run uphill to form ice shelves.

Yes I tried to find an answer myself but most sources just seem to wander off into warming consequences.


Blue: I will give this a shot. The first thing to take into consideration is the materials properties of ice. We are used to ice being brittle and shattering when hit or crushed. However, in its bulk form, ice is elastic or plastic depending on how it is stressed. In other words, ice can flow as a fluid under plastic deformation due to stress. However, it is very viscous and it flows slowly under high loads. Some think of glaciers just sliding while maintaining form. Cont

Nov 02, 2015
For Blue continued: If you look at a glacier that is flowing you will see it is similar to a river flowing (although at a much lower rate). The importance of the grounding line is that it keeps a force on the leading edge of the glacier that prevents it from both flowing and sliding. Once the grounding edge comes loose the glacier accelerates and can pull on the flow behind it, speeding it up. This all requires us to recognize that the ice is flowing and parts of it are moving faster than others (again, back to a flowing river). There is some good information here:

http://www.antarc...g-lines/

There are some papers here:

http://www.antarc...tartica/

Continued

Nov 02, 2015
Blue said:
I'm not clear how the melting ice sheet seems to run uphill to form ice shelves.


It does not run uphill. Instead, the lower section of it is melted off by the warmer ocean water. As the lower section of the ice is melted off, it lifts slightly and slides more of it forward to solidly ground itself. If it can't do that the ice slides until it is grounded or just slides if it does not ground. However, the tension from the ice behind it will keep it from sliding too fast as the ice sheet plastically deforms.

There is another interesting effect in that some ice sheets can come out of valleys that have the base of the ice sheet below sea level on land. The weight of the ice sheet can push the water out from under it or rapid melting can cause the whole sheet to float or parts of the sheet to float and that makes it easier for the sheet to move through the valley. Continued

Nov 02, 2015
For blue continued: However, even if the sheet is not floated, just like a river, part of the flow can move or eddie and you can wind up with the lower part of the ice moving slower than the upper part of the ice, so, again, the ice is not moving upward, but the upper portion can be moving faster than the lower portion so it gives the impression that it might be moving upward. A good way to see ice flow under pressure is to get a substantial piece of ice and put it into a refrigerator. Hang a weighted thin wire over the ice and let it go slowly. You will see that the wired can move completely through the piece of ice without cutting it in half because it melts the ice under the wire then refreezes it behind the moving wire.

You can also SLOWLY compress a piece of ice with a hydraulic jack and watch it flow around the jack faces (slowly over the course of days). Water is wonderful stuff.

Does that help or are there other questions I missed?

Nov 02, 2015
Thermo, thank you for taking the time to provide food for thought. Water is indeed wonderful stuff.

Nov 02, 2015
Thermo, thank you for taking the time to provide food for thought. Water is indeed wonderful stuff.


Water is great stuff. Just the number of ices that can be made at different pressures is amazing.

I don't know if I answered any of your questions but it did give me the opportunity to check on some of the things I was not sure of either. There is a wealth of information available, but, as you pointed out, it is not a simple system. Let me know if there is more you want to discuss.

Nov 03, 2015
I read that volcanoes under West Antarctica are causing the ice melt there, but no mention is made of that in the article.

Nov 03, 2015
I know the way to dry land!

@BartV science does not use absolute statements. Likely, could, may are common unless you are without a doubt certain and science cannot be in the majority of cases.

Nov 03, 2015
The climate? It's just a vehicle, a pretext for uprooting the only economic system in history that has brought prosperity and good health

Nov 03, 2015
cjones1 states
I read that volcanoes under West Antarctica are causing the ice melt there, but no mention is made of that in the article
The amount of heat generated and in respect of the state of activity of all geothermal sources beneath has been analysed for a long time, the amount is comparatively much smaller than that from CO2's contribution re radiative forcing. Also it should be considered that the bulk of melting is where the sea is in close proximity to ice regardless of any geothermal sources.

The amount of heat Earth is retaining in the energy balance is significant and getting more so, ie
https://en.wikipe..._forcing

Which comes from the settled Physics known for > 100yrs detailed here:-
https://en.wikipe...transfer


Nov 03, 2015
Shootist claims
The climate? It's just a vehicle, a pretext for uprooting the only economic system in history that has brought prosperity and good health
But, ignores the Physics, see my last post or where you can tell us what is incorrect re the Physics & Maths of the core issue

https://en.wikipe...transfer

&

https://en.wikipe..._forcing

Unfortunate fact for oceans & glaciers is water has approx 4000x the specific heat of atmosphere and therefore atmospheric temps are subject to much higher noise variance, the key issue must be enthalpy, in that respect its important to focus on the temperature of the materials with the highest specific heat and how that material is; Exposed to Sun's energy, moved, changes phase ie Increasing evaporation in relation to Psychrometry which proves it is raised by another cause other than the sun, ie the increase in atmospheric water vapour can only come from CO2 forcing - all else equal

Nov 03, 2015
BartV claims
Science does not generally use "could". "Will" is the correct term
No !

Science is firmly grounded in Probability & Statistics and therefore there is never 100% certainty of anything, there is only the balance of probabilities. Engineering, when pressed by commercial pressures often resorts to 'will' as does media which misunderstand the discipline of Science.

BartV suggests
Otherwise, it is best to keep your mouth shut
Given there is no certainty in the truest use of Science, then clearly it is appropriate and recommended one opens one's mouth to ask questions and seek higher education.

This is of course dependent on one checking first before making claims not congruent with the core ethics of Science in respect of Mathematics as the "Balance of Probabilities" etc

Claiming Science is about 'will' is incomplete as you confuse with engineering disciplines, the more appropriate paradigm is the use of the word 'likely' or 'unlikely' etc...

Nov 03, 2015
The climate? It's just a vehicle, a pretext for uprooting the only economic system in history that has brought prosperity and good health

So the climate does not exist.
Boring, factless.

Nov 03, 2015
I read that volcanoes under West Antarctica are causing the ice melt there, but no mention is made of that in the article.

So you wrote it and then read it.
Reading before posting is good, but does not prove much.

Nov 03, 2015
Science does not generally use "could". "Will" is the correct term.
Otherwise, it is best to keep your mouth shut
@bartv
science is about defining reality around you, which requires measurement
measurement is about the limitations of the measuring device... if you have a rule that calls out inches only, with no other graduations, then you can only measure to the smallest scale of 1 inch: anything less is subjective and must be guessed at
this is obvious when you think about it, but i suggest going here for more details: http://ocw.mit.ed...=physics

in Physics 101 (Especially in the course by Lewin) this is addressed before anything else
see also the post by: ProcrastinationAccountNumber3659

in ALL science, you will find error bars as well as probabilities
especially in a highly complex system or issue
http://physicsbuz...ery.html

Nov 03, 2015
Hi dogbert. :) Just in again for a few minutes, so briefly...
The marine ice sheet is already in the ocean. It can break off or melt with no increase in sea-level rise.
It's to do with what proportion of the ice body is immersed in ocean water. The land continental shelf slopes underwater for some distance beyond the coastal land surface fringe, so any glacial ice sheet flowing into that marine water will still be prevented from immersing as much as it would do in open ocean where depth of water is at least as great as vertical thickness of glacial body. In short, marine ice sheet extending into coastal slope waters may be much much thicker than depths of water covering the closer inshore parts of that slope, so marine ice sheet is NOT 'floating free' like icebergs do; so doesn't displace as much water as it would if 'fully floating free' like iceberg/sea-ice. Cheers, :)

Nov 03, 2015
Reading before posting is good,
Funny, the literal read of the guidelines for commenting link: "please read before you post."

So it goes without saying, I guess, the importance of comprehension.

Nov 06, 2015
Seems a lot of AGW deniers arbitrarily follow business camps & still refuse to get a base education in the essential proven (for >100 yrs) underlying Physics of heat

Instead some arbitrarily track the perceptions of that which the major business groups do & although there's evidence some business groups accept Science advice Eg Rothschild divesting
http://www.thegua...e-change

But, below critical mass perception as yet. Bloomberg group is perceived a leader coalescing input from many commercial movements, here is their important view on AGW
http://phys.org/n...kic.html

Of course essentials of greenhouse gas properties is that which retains heat
https://en.wikipe...transfer
leads to
https://en.wikipe..._forcing
& which lifts H2O re
https://en.wikipe...ometrics

Can ANY denier refute the core Physics, anywhere ?

Nov 06, 2015
Apologies, too many tabs open, preparing other windows for my 18 forums... Quora.com has some discussion on this too, re my last post here, as most have experienced phys.org edit option often removes links when there are 2 or more and sometimes adds useless text messing up prior text if close to 1000 chars...

The correct Bloomberg link is this
http://www.bloomb...e-world/


Nov 07, 2015
Uncertainty... may... could


Nov 08, 2015
Yes well should the world get warm enough to melt that much ice, it will also get warm enough to make vast stretches of currently inhospitable Siberia and Canadian taiga and tundra suitable for human settlement and development.

This is especially true, because in the intervening 1000 years of so humanity should we persist will have advanced technologically to the point that we'll likely be able to use the tech. we would be using to terraform Mars (at that point in time) to make everything fine back home.

So no big deal.

The consequences of global warming on the scale of centuries is a foolish worry, unless someone assumes civilization is going to collapse and humans will return to living in stone age conditions with the commensurate lack of advanced technology save stone tools. LOL

Nov 08, 2015
Jonseer states
...should the world get warm enough to melt that much ice, it will also get warm enough to make vast stretches of currently inhospitable Siberia and Canadian taiga and tundra suitable for human settlement..
NOT that simple at all !

Energy to melt ice is HUGE in comparison to H2O. ie To melt ice @ 0 C to water also @ 0 C is ~>150 TIMES energy it takes to heat water by just 1 C

It means if same energy rate applied to water, would rise in temp by up to 150 deg C, please LEARN
https://en.wikipe...f_fusion

Jonseer imagines
This is especially true, because in the intervening 1000 years of so humanity should we persist will have advanced technologically..
Really ?
Show us how focused politicians are well managed to do something practical in a timely manner ?

Jonseer claims
So no big deal
Very Wrong !
Do calcs on "Latent Heat of Fusion", high school stuff, heat retention:-
https://en.wikipe..._forcing

Nov 10, 2015
Seas may rise 3 ft while the Mediterranean dries up and meantime the sea level at Venice is still historically low. My wager is nobody is right and and Antarctica is gaining ice over all yet the ice shelf is melting. OK. Whatever. Bet you cannot stop the world changing. Bet the sun is the main climate engine. Bet you just want to steal money and power. Bet the world will not let you.I bet if you wish to survive you can stop crying and start adapting. You shouldn't try to teach your grandmother to suck eggs.

Nov 10, 2015
Seas may rise 3 ft while the Mediterranean dries up and meantime the sea level at Venice is still historically low. My wager is nobody is right and and Antarctica is gaining ice over all yet the ice shelf is melting. OK. Whatever. Bet you cannot stop the world changing. Bet the sun is the main climate engine. Bet you just want to steal money and power. Bet the world will not let you.I bet if you wish to survive you can stop crying and start adapting. You shouldn't try to teach your grandmother to suck eggs.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more