Collapse Of Greenland Ice Shield - Consequences

[barb162]

Collapse Of Greenland Ice Shield - Consequences

By Dr John James

08 August, 2006
Countercurrents.org

The Greenland glaciers that cover the island contain enough water to raise sea level twenty feet, or seven meters. It was once thoughts (and that was only six years ago) that the glaciers would be self-sustaining even in a warming world because of size and so on.

We now know that this is not true. Not only are the edges melting fast, but the surface melt is seeping through the ice to lubricate the junction between the ice and the rock underneath. This is the unexpected factor that has turned scientific attention onto this escalating problem.

It appears that the Greenland ice is shot through with crevices, tunnels and faults through which the melting upper surface can penetrate right through the glacier, and threaten to break the attachment between the ice and the rock base.

When this happens much of this mountain of water will flow into the sea. Already twenty-one of the great glacial masses are moving seawards eight times faster than ten years ago. It would seem we are on the verge of a major tipping point in climate change, if we have not already reached it.

snip
http://www.countercurrents.org/cc-james080806.htm

[kaygore]

1. Just another reason to kick LieberBush out--Global Warming

We can't do anything as long as Bush, Lieberman, and the like support false science.

If LieberBUSH had been even a half decent VP candidate, we would be addressing this NOW instead of wasting trillions on a war that we can't win nor would want to.

[barb162]

2. If people don't start voting for REAL environmentalists

who are willing to make some hard decisions, everyone better start moving off the coasts of every country on the planet. What people are going to do in countries like Bangladesh and other low lying areas, I give up already

[longship]

3. Blub blub blubbubluh blubub blub

:kick:

[MsKandice01]

4. Wait, wait, wait...WHAT?!?

"The latest US Navy survey suggests there will be no sea ice left in the Arctic summer by 2016."

Can someone substantiate this?

[longship]

5. I've heard this, too.

Buh-bye Santa Claus.

Hello, Northwest passage.

[Dead_Parrot]

6. it's a new one on me...

I'd be interested in seeing a link, but it sounds a bit soon even by my manic depressive standards...

[phantom power]

7. Maybe hatrack knows, he's been tracking the sea ice decline

[htuttle]

8. I've read the same prognosis from the Nat'l Snow & Ice Data Center

I think they were saying that if current (2003) rates of melting continue, not only will all Arctic sea ice be gone in summer by 2016, but it will be gone all year round by 2030.

Here's some links that mention the 2030 "gone all year round" date from NSIDC, in any case:
http://www.guardian.co.uk/science/story/0,,1774815,00.html
http://environment.about.com/b/a/256738.htm

[bananas]

9. So is the author saying that with no water ice to hold back the land ice,

Greenlands ice will slide into the ocean around 2016?
How long will it take for the oceans to rise 20 feet?
Larson-B collapsed in 35 days, IIRC.
Will this be like a world-wide tsunami, a mile-high wave near Greenland that gradually reduces to a 20-foot wall of water when it reaches Hawaii?
Or will sealevel slowly rise for a month at no more than a foot per day?

[Dead_Parrot]

11. More like an inch or three a year, I think.*

It's not all going to slump off when the last ice-cube melts at the pole, but it will accelerate it's slide.

But now would be a good time to get that beach-house on the market.

*Disclaimer: I'm always more optimistic in the mornings. Ask me again in 12 hours. :)

[happyslug]

14. Larson B was an Ice Shelf, not an ice Sheet

The real danger are the melting of the Ice Sheets, for that will be adding water to the ocean. An Ice Shelf floats on water already and thus displace the water it will be when it melts.

As I pointed out below, the Greenland Ice Sheet is grounded ABOVE ocean levels and as such can only melt so far so fast. The real concern in the West Antarctic Ice Sheet (WAIS) which is grounded BELOW sea level and thus affected by world wide Ocean temperatures. Larson-B was one of the Shelves protecting the West Antarctic Ice Sheet from the full affect of increase Ocean temperatures.

[happyslug]

13. First, the Greenland Ice Sheet is not the real danger.

First, while it is one the Arctic Circle (as opposed to be within the Arctic Circle) it is grounded above sea level. The significance of this is that what is most likely to happen in the case of Greenland is for the ice to slowly over the next 20-30 years slip into the Ocean while not being replaced by new snow falling on Greenland. Thus you will have a slow increase in world wide ocean levels.

As to the Arctic ocean melting, while worrisome for other reasons, just it melting will have almost no affect on world-wide ocean levels. The reason for this is the ice on Arctic Ocean are ice shelves NOT ice Sheets (Ice Sheets are GROUNDED on land or seabed and thus represent MORE water then if melted). Ice Shelves FLOAT on top of water, displacing the same amount of water they would be if melted. Thus if the Arctic Ice Shelves melt, world wide ocean levels will NOT go up.

Now, the disappearance of the Arctic Ice Shelves is worrisome for two reason, first Polar bears live ON the Shelves and use them to hunt seals. Thus the disappearance of Ice Shelves will affect Polar bear habitat and the rest of the habitat of the Arctic. The Second problem is that present theory holds that Ice Shelves protect Ice Sheets from direct attack by warming sea water. Thus if the ice Shelves disappear, the warmer ocean water will come right against the Ice Sheets and cause them to melt faster (This is more a concern with the West Antarctic Ice Sheet more than the Greenland Ice Sheet).

Now lets get ourselves really scared, lets look at the West Antarctic Ice Sheet (WAIS). Right now it is winter in the Antarctic, thus the ice Shelves around Antarctica are still expanding (and will expand till the Middle of September when they will reach their annual widest expansion and then start to melt as the Antarctic goes into Spring and Summer. Come next March, the Antarctic will be are its smallest do to the summer melt.

This brings us to the problem of the West Antarctic Ice Sheet (WAIS). Unlike the Greenland ice Sheet and the much larger East Antarctic Ice Sheet (EAIS), the West Antarctic Ice sheet is grounded BELOW sea level. West Antarctica, unlike the much higher and solid East Antarctica, is a Series of Islands around which the West Antarctic Ice Sheets flows around into the Ross Ice Shelf or the Ronne Ice Shelf.

Thus, being grounded below sea level, the West Antarctic Ice Sheet is affected on its margins by Ocean temperatures. Thus, unlike land grounded Ice Sheets, the West Antarctic Ice Sheet (WAIS) can deteriorate rapidly, i.e. break up and start to float overnight. The West Antarctic Ice Sheet (WAIS) contains as much water as the Greenland Ice Sheet (Both Ice Sheets contain about 12% of the world's Fresh water, the East Antarctic Ice Sheets hold 70% of the world fresh water, the rest are in lakes, ponds, rivers and mountain glaciers).

Thus, while the Greenland ice Sheet can slowly raise ocean levels, we will have time to manage such an increase (Either by building walls to keep the ocean out OR by abandoning areas as the ocean levels rise). This is NOT true if the West Antarctic ICe Sheet collapses. What you will see is a rapid, over night, increase in world wide ocean levels of about 20 feet (Good-bye Florida Everglades and lower Manhattan as while as the water front of most US east Coast and Gulf Cities, the West Coast will see their harbor underwater, but given the rapid raise of the North American Continent over the Pacific Ocean, the amount of land under water will be minimal compared to the East and Gulf Coasts).

Thus, while the melting of the Greenland Ice Sheet will be a disaster, it will one that can be manged over a period of anywhere from 20-100 years (Depending on the estimate of how long will it take the ice to melt and/or move from Greenland into the Ocean). On the other hand all the West Antarctic Ice sheet has to do is to start to float WHERE IT IS LOCATED to raise world wide ocean levels 20 feet. Remember once an Ice Sheet starts to float it is an ice Shelf and any Ice Shelf will DISPLACE the same amount of water that is in Ice Shelf. This is why the West Antarctic Ice Sheet (WAIS) can do the same amount of damage as the Greenland Ice Sheet but over a much quicker time period.

[Boomer]

15. Thanks for this explanation

Thanks for taking the time to explain this so thoroughly -- very enlightening.

And just a little worrisome...

:scared:

[happyslug]

16. IT is believed to have happened 100,000 years ago

In the so-call "Mad-House" Century. In a period of less than 100 years (and maybe less than 50 years), world wide ocean levels ROSE 20 feet and then FELL 80. We know what caused the FALL, the latest expansion of the Ice age Started and this took up water from the Oceans and into much expanded Ice Sheets located where the present Greenland, West Antarctic and East Antarctic Ice sheets are. Further water was removed and into the North American Ice Sheet (Collapsed at the END of the last Glacier maximum) and the various Glaciers located in Scandinavian and Mountain regions of the World.

While we know what caused the DROP in ocean levels, we do NOT know what caused the earlier RAISE in ocean levels. IT was rapid according the study of Coral Islands, thus any collapse of the Greenland and the East Antarctic Ice Sheets probably did NOT cause the In cease. That leaves the West Antarctic Ice Sheet.

The present theory is do to high carbon dioxide level (very similar to today's carbon levels, probably caused by increase Volcano Activity) caused a spike in world wide Temperatures, which lead to the West Antarctic Ice Sheet to collapse. This pushed cold water into the the Southern Pacific and Atlantic Oceans causing the world wide ocean conveyor system to break down. This break down caused world wide temperatures to drop and cause the last ice Age.

An alternative theory is that the Collapse of the West Antarctic Ice Sheet released huge amount of Iron and other trace elements into the Southern Pacific. Today this area is a Ocean Desert for algae an NOT live in that area do to lack of iron and other trace elements that is absorbed by algae closer to the Continents. Adding Iron causes algae to bloom in this area, so it has adequate sunlight and other elements for algae to thrive, but it lacks dissolved iron so that Algae can NOT thrive (Iron appears to just one of several elements needed for the Algae to be self-sustaining if the trace elements are added, iron just appears to be the most important). The alternative theory is that the Collapse of the West Antarctic Ice sheet threw a huge amount of iron and other elements into the Southern Pacific casing a rapid expansion of Algae in the Southern Pacific and Indian Oceans. This expansion caused the Algae to to withdraw Carbon Dioxide from the Air as part of the Alga's process of converting Sunlight for its use. This withdraw of Carbon Dioxide caused the world temperatures to DROP, bring on the last ice age.

More on the madhouse Century:
http://www.imaja.com/as/environment/can/journal/madhousecentury.html
http://ces.iisc.ernet.in/hpg/envis/doc98html/globalcll1119.html

[Boomer]

17. About that time line...

>> IT is believed to have happened 100,000 years ago

Genetic studies have shown that homo sapiens experienced a serious population bottleneck around that time, a reduction to a small number of individuals, eventually followed by an expansion.

Which strongly suggests that such an event will have catastrophic consequences for our current population.

I suspect that the industrialized nations will actually have a harder time surviving such an event because citizens have become so dependent on a complex infrastructure to produce and distribute the basic necessities of life. Unlike 100,000 years ago, the average person living in an urban area has no clue how to grow food, store and preserve it, make tools, or just generaly survive by scrabbling on the land. If the society collapses into anarchy due to the sudden, wholesale destruction of our coastal cities, people simply won't be able to cope.

[Delphinus]

34. I wonder, Boomer,

if there is a way to assure that those who survive and will repopulate the planet will be loving, kind, compassionate people. All scenarios seem to point that the rich, greedy, and in-it-for-themselves are the ones who will have access to survive. Unfortunate.

[Boomer]

35. How realistic is that?

In a hard-scrabble world in which there is simply not enough food to go around, who do you think will win the fight for survival?

1) an individual who is loving, kind, and compassionate
2) an individual who puts his own family first, and will do ANYTHING to keep them alive

There's a reason humans have such a nasty streak in their character: it's helped us survive past times of enormous upheaval and scarce resources.

Of course, there's also a reason that humans have the capacity for love, kindness and compassion: it's helped us prosper in times when mere survival is no longer an issue.

So we're a half-empty/half-full kinda species, which is a good or a bad thing depending on which half of the glass you're trying to drink from at any given time.
:P

[Strelnikov_]

28. "This Withdraw Of Carbon Dioxide Caused The World Temperatures To Drop"

See, there's nothing to worry about.

Carbon Dioxide. We call it pollution. The algae call it life.

[Hoping4Change]

18. Very informative. Thnak you.

:yourock:

[bananas]

20. How high would the world-wide tsunami be?

"a rapid, over night, increase in world wide ocean levels of about 20 feet"

If Greenland takes 20 years to raise sealevel 20 feet, that's a gradual increase of a foot year.

But if WAIS causes a 20 foot increase over 24 hours, that's an average of about a foot an hour. I imagine that would propogate as a series of very large waves, a world-wide tsunami, small waves perhaps at Novia Scotia but much larger at New York and even larger at Australia. How high would this wave be at NYC? Would it wash away the suburbs?

[happyslug]

22. I suspect it will be a gradual raise within a 24 hour period.

Remember a Tsunami is the product of a rapid change in sea floor levels that acts like an agitator on a washing machine. If the WAIS just starts to move into the Southern Ocean (The technical name for th ocean around Antarctica) you may NOT have a rapid agitation but a gradual but rapid raise.

Now I have read about the Azores' Volcano. Every so often (In geological terms which can means once every couple of thousand years) the side of the Island falls into the Atlantic and causes a Tsunami in the direction of New York City. This Tsunami is caused by a rapid fall into he ocean o a huge amount of Earth. While I do NOT see the WAIS doing the same, it might very while act the same way, no one nows and from i have read there is no evidence of such a Tsunami the last time the WAIS collapsed.

Now, what may happen is the Collapse of the WAIS leads to a Tsunami but directed straight alone the International date line Ross sea, so that any resulting Tsunami will not hit anything till the Aleutian islands and then Alaska and Siberia. The same with the Ronne Ice Shelf, it may direct any Tsunami to the "gold coast" of Africa (Nigeria, Liberia etc). Either way no direct affect on Europe or America (Both North and South America). This is complicated by the existence of the Ross and Ronne Ice Shelves, which may act as a barrier to any Tsunami from forming (i.e. The Tsunami expends its energy moving the Ross and Ronne Ice Sheets out to sea to permit the Ice Sheets to follow.

Thus what I suspect will happen is just a steady increase in sea level as opposed to a Tsunami, but since I have no records from 100,000 years ago when this last may have happen your guess may be as good as mine.


Here is a map of Antarctica, the West Antarctic Ice Sheet is between the Ross and Ronne Ice Shelves on the Map (just South of South America):


Map of Antarctica colored for area BELOW sea level:
http://en.wikipedia.org/wiki/Image:AntarcticaRockSurface.jpg

[bananas]

23. Thanks for the detailed explanation.

Hopefully we'll get enough advance warning to evacuate low-lying areas.

[Odin2005]

24. You're assuming the whole sheet will lift off all at once

IMO what will happen is that it will disintergrate in stages over a few years as water infaltrates under the sheet

[happyslug]

25. As I said, no one knows, the records from 100,000 years ago are rare.

Thus all we can do is speculate based on what we do know about the Ice Sheets AND what happened 100,000 years ago. The rationale for a RAPID decline is that once the edges of the Sheets starts to go, it builds on itself, much like how an earthen dam breaks. The water goes over the top, takes the top level off, this exposes the next level WHILE THE TOP LEVEL IS STILL ON TOP. Thus you have Two levels going then 4 then 8then 16 than 32 then 64, then 128 then 256 then 512 than 1024 then 2048 then 5096 then 10,192, then 20,384, then 40,768, then 81,536.... Soon the whole dam is gone. Thus it is possible for the West Antarctic Ice Sheet to collapse rapidly as each part leaves the next open to Collapse.

The other alternative is that as the Ice Shelves and then the Ice Sheets, melt, this exposed earth which tends to be dark color so it absorbs more sun than the white ice of the Ice Sheet and Ice Shelves (White tends to reflect sunlight and thus makes thing colder). Thus on a more gradual basis you will see over just a few years the ice sheets come under larger and larger attacks by the warmth of the ocean and the exposed ground and water to sunlight.

The kicker in this situation is the Antarctic Volcanoes. Lake Vostok is believed to be a lake below the Antarctic Ice Cap kept liquid by geothermal activities. There are other similar lakes. How active are the geothermal activity keeping these lakes liquid? Are they interconnected? (There is some evidence for this). All the one's I have seen are under the East Antarctic Ice sheet, if the West Antarctic Ice Sheet would break up would this expose some of the interconnected rivers, and thus EMPTY even more fresh aster into the world's oceans. We do not know and the best e can do is guess.

For more on Lake Vostok:
http://en.wikipedia.org/wiki/Lake_Vostok

[barb162]

27. Doen't this mean aeveryone living on coasts should get off

the damned coasts. And low-lying places places like Florida, Louisiana, NYC,ETC., people just shouldn't be living there? Not even mentioning countries around the world with the same problem

[bananas]

30. half the population lives within 50 miles of the coast

or something like that, IIRC.

[happyslug]

37. The key is how FAR up are those people.

For example the West Coast of the US raise rapidly, do to the North American Plate is smashing into the pacific plate forcing all of the land at the impact area upward.

On the other hand the East coast raise less rapidly, but even most of Florida is more than 20 feet above sea level (The everglades is below that point, thus southern Florida will disappear).

[bvar22]

10. Rising water level not the only threat.

According to Al Gore, that much "Fresh Water" injected into the oceans of the North Atlantic would stop the flow of the Gulf Stream.

[hatrack]

19. There's also thermal expansion to contend with

It may have added a substantial chunk (i.e. 20%) to sea level rise to date.

[phantom power]

21. I calculated something like 2 feet of rise due to thermal expansion....

I think that was assuming a uniform 1C increase in ocean temperature, which of course is oversimplified, but it shows that a significant rise is possible just from increasing ocean temps.

[happyslug]

26. I read a few years ago that it had been estimate at about 2 inches.

I can not find the source of that information, but it had been based n the VOLUME of the Ocean as while as the expansion of the water in the ocean.

[phantom power]

31. I applied the thermal expansion coefficient of H2O to the volume...

of the world's oceans. I got the increase in volume, and then divided by the surface area of the oceans. I figured that would be a pretty good approximation. I think I posted the result in this forum, but that was a long time ago.

The probability of my calculation being wrong is... well... greater than zero :-)

[BrightKnight]

12. plate tectonics and massive weight redistribution

Removing that much weight from a small area and adding 20 feet of water to the worlds oceans might trigger seismic events

[bananas]

29. a domino effect

sudden sealevel increase leads to massive earthquakes which cause massive tsunamis

[Nihil]

32. I'm glad it's Friday ...

... I don't think I can take much more of this uplifting news ... :scared:

[XemaSab]

33. There would be isostatic adjustments

But aren't those typically long, slow movements, and not sudden events?

[Odin2005]

36. Yes and No.

Isostatic reajustments happen slowly, but can reactivate dead faults, cauing massive earthquacks. The New Madrid Fault under the lower Mississippi floodplain is a Pre-Cambrian fault that was reactivated when the last ice age ended.