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Ice Shelf Disintegration Threatens Environment, Queen's Study

Knight-Dragon

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We are all going to drown...

http://www.sciencedaily.com/releases/2005/08/050804123855.htm

The spectacular disintegration of Antarctica's "Larsen-B" Ice Shelf was unprecedented since the last ice age, according to a recent study to be published next week in Nature. And the disintegrating Antarctic ice could have huge implications for global warming and rising sea levels.

Using sediment core and oxygen isotope analysis, researchers have recently proved that Larsen B -- which disintegrated in 35 days in 2002 -- had been a stable ice shelf 200 metres thick with a surface area of 3,250 square kilometres for at least 10,000 years. By contrast the Larsen A Ice Shelf, which broke up in the 1990s, was absent for a significant part of that period and reformed beginning about 4,000 years ago, according to the study.

"The disintegration of Larsen B is almost certainly a response to human-induced global warming," says Queen's geographer Robert Gilbert, the only Canadian researcher on the international research team. "Antarctic temperatures have increased more than 10°C in the last 25 years. By comparison, the world-wide temperature change during the entire post-glacial period has only been 2 -- 3°C," he adds.

Larsen B's demise is likely the consequence of long-term thinning due to melting from underneath as well as short-term surface melting due to global warming. The "under melt" of a few tens of metres over thousands of years is caused by warming waters or currents flowing beneath the floating ice shelf. However, the surface melting has happened much faster over decades, the study concludes. And Larsen B's demise could set off a series of environmental changes.

"The breaking up of Larsen B alone will not change sea level, but other glaciers previously restricted by the ice shelf have surged forward, lowering their surfaces," says Dr. Gilbert. "Lower elevations have warmer temperatures, which warm the glaciers and cause more melt and more flux of ice to the sea. So that is having and will have an effect on global sea levels. As more ice is lost there may be a greater impact on sea level than previously predicted.

"Further, with the increased energy in the atmosphere associated with global warming, there will be more storms," he warns. "Storm surges, which also raise water levels, will have profound effects on low-lying areas and may necessitate infrastructure like the large moveable dams called surge gates already used in Europe and Providence, R.I., that can be closed during extreme high sea levels to prevent flooding."

Although other, smaller ice shelves have undergone periodic decay and growth since the last ice age, these small ice shelves exist at the climatic limit for ice shelf formation and would be expected to respond quickly to climate change over hundreds and thousands of years, the study indicates.

The research team also includes scientists from Hamilton College in New York State, Colgate University, the Lamont-Doherty Geological Observatory at Columbia University, Montclair State University in New Jersey and Southern Illinois University.

Larsen ice shelf. (Image courtesy of Queen's University)
 
As far as the scientists who live in Antarctica can tell, the ice sheet is actually getting thicker. The Larson ice sheet was floating on the ocean, and it's breaking off and melting is part of a natural cycle. Since most regions of the continent never or rarely get above freezing, the ice never melts, and is pushed to the edges by the gradual accumulation of snow from precipation. These sheets extend over the ocean, and when they get too big, break off and float away. Again, completely natural, not a result of global warming, and since ice floats, it does not contribute to rising ocean levels. In other words, this is insignificant.
 
On the whole, I remain on the sidelines, having once again seen one person say one thing and another person say the opposite.

I disagree with that last bit, Taper--provisionally. Something that floats always displaces water exactly equal to its weight. However, if the Larsen ice shelf was attached to a floating mass to begin with, then the extra water displaced by the broken-off shelf must be exactly balanced by the loss of weight of the mass that used to support the shelf. Net change in planet's ocean level: zero.

I think it's more likely the Larsen shelf was indirectly attached to the ground, however. In which case: if the entire Larsen B ice shelf was out of the water, and if those figures in the original article are accurate, the whole shelf had a volume of 3,250 x .2 = 650 cubic kilometers. Divide that by the surface area of the oceans--360 million square kilometers--and the ocean level goes up by .0000018 kilometers, or 1.8 millimeters.

:eek: Okay, that's definitely cause for alarm--if you're sleeping on the beach, with your head right down on the sand and your nose barely above the waterline. :)
 
Well, the issue is the Ice Shelf acts as a dam for glaciers on land behind it. With it's disintigration there's a larger chance that ice from Antarctica while slide into the ocean, and that will cause global sea levels to rise.
 
You have to remember, even solids like ice will bend, especially on the scale of a thousands of square kilometers. The ice shelf was floating on water, not cantilevered out across the ocean. Simple fact is, the Antartic ice sheet is getting thicker, no matter what the global warming activists say. Virtually every reputable study shows this. I'm too drunk to find the sources, but it shouldn't be that hard. I'm not saying global warming doesn't exist, only that it doesn't really affect a place that stays far below freezing all the time.
 
taper said:
You have to remember, even solids like ice will bend, especially on the scale of a thousands of square kilometers. The ice shelf was floating on water, not cantilevered out across the ocean. Simple fact is, the Antartic ice sheet is getting thicker, no matter what the global warming activists say. Virtually every reputable study shows this. I'm too drunk to find the sources, but it shouldn't be that hard. I'm not saying global warming doesn't exist, only that it doesn't really affect a place that stays far below freezing all the time.

The assertions you make as to thickening ice Antarctica is, if I recall correctly, virtually opposite to my understanding - I'm pretty annoyed when people demand a source, simply because they don't like something that has been said - but I'm interested in checking on this, so wondered if you might have any relevant links or sources to help me out?
 
You're likely to find, 10Seven, a whole bunch of sites that say one thing and a whole bunch of sites that say the opposite.

Probably something else that needs to be asked is, what percentage of the planet's ice is under water? When you look at a floating iceberg, the actual mass is ten times the amount you see above the surface. If ninety percent of the world's ice is submerged, then the ocean level won't rise at all even if all of it melts.

This is all aside the original point, which is that the melting of Larsen B is simply a symptom of the planet getting set on "Bake", but it's interesting nonetheless. :)
 
TAPER
Thanks for the links.

BASKETCASE
Good point - I tend to be pretty cynical when it comes to assertions made - preferring my own observation ;) which has it's own bias.

I recently came across of some statistics of seaborn ice - it would seem that if all the ice in the ocean melted, it could well lower :crazyeye: but the real issue is to landbound ice, which accounts for a far larger mass and quantity - which must be where this ice-shelf thing is a real kicker...
 
A few things:

Only part of the ice sheet is getting thicker, and the (likely) reason for this is increased snowfall due to global warming. However many of those same reputable studies suggest that the rate of melting on the coasts is still greater than the rate of thickening.

The fact is any amount of prolonged ice cap melting cannot be considered a good thing, and while the melting of floating ice wont do any harm sea-level wise, it does mean we are getting closer to the melting of land-ice, which will.
 
Truronian said:
A few things:

Only part of the ice sheet is getting thicker, and the (likely) reason for this is increased snowfall due to global warming. However many of those same reputable studies suggest that the rate of melting on the coasts is still greater than the rate of thickening.

I have read of the snow-fall issue too.
 
taper said:
As far as the scientists who live in Antarctica can tell, the ice sheet is actually getting thicker.
sources?
conclusions?

The Larson ice sheet was floating on the ocean, and it's breaking off and melting is part of a natural cycle.
have you even bothered to read the article?

pbviosuly not :rolleyes:
Since most regions of the continent never or rarely get above freezing, the ice never melts, and is pushed to the edges by the gradual accumulation of snow from precipation. These sheets extend over the ocean, and when they get too big, break off and float away. Again, completely natural, not a result of global warming, and since ice floats, it does not contribute to rising ocean levels. In other words, this is insignificant.
false - but realizing this requires reading the article, something we don't want to bother you with. it never rains in California, after all.....
 
taper said:
You have to remember, even solids like ice will bend, especially on the scale of a thousands of square kilometers.
Ice is not a solid
The ice shelf was floating on water, not cantilevered out across the ocean.
erhm, who claimed it was????
Simple fact is, the Antartic ice sheet is getting thicker, no matter what the global warming activists say. Virtually every reputable study shows this. I'm too drunk to find the sources, but it shouldn't be that hard.
hm, why does that sound like a cheap excuse?

from your 'sources':
New research has found that parts of the ice sheet that covers West Antarctica may be getting thicker, not thinner, as scientists have feared.

note the word 'part'?????

and this:
The ice sheet covering the interior of Antarctica is thickening, researchers report in the journal Science.This bulge, which was recorded by satellite, may temporarily buffer rising sea levels, they believe. Antarctica's "weight gain" is due to extra snowfall, caused by rising temperatures, the US-UK team thinks.

However, the scientists worry the overall mass of the Antarctic may be decreasing because ice near the coasts is melting, possibly at a greater rate.

if you bother to read more than the first two sentences..... :rolleyes:

for this link: http://www.globalwarming.org/article.php?uid=165

chck who's behind them: http://www.consumeralert.org/ncc/members.htm
an interest group that has NO interest in the truth.....

as for the Wiki link - what is it supposed to add to the problem we are discussing?


I'm not saying global warming doesn't exist, only that it doesn't really affect a place that stays far below freezing all the time.

:lol: Does it? Have you ever been there? Have you checked temperature graphs?




no, you just repeat the mantra of the GW deniers.
 
taper said:
This thickening is localised and small compared to the much larger issue of surface melting.

It is like filling a room with toxins and saying "It is OK, there is a small window somewhere.."
 
Either that, or one guy is smoking and a bunch of people are pointing to the little curl of smoke in that corner of the room and going "ACK! He's suffocating us all!!!" :rolleyes:
 
I bet someone just forgot to turn down the central heating in antartica. They really should fix that.
 
BasketCase said:
Either that, or one guy is smoking and a bunch of people are pointing to the little curl of smoke in that corner of the room and going "ACK! He's suffocating us all!!!" :rolleyes:
Either you didn't read/understand the links or you are willfully ignorant. Take your pick...

After reading tapers post I *had* to read all the articles and they do not support the "nothing to see here" argument at all. I wonder if taper bothered to read them himself? :hmm:

Come on basket - just because Bush say's it's so, doesn't mean global warming is a lie made up by "liberals". ;)
 
Global warming has been a fact for 10.000 or 20.000 years now.......

It's also a fact that melting floating Icebergs do not raise the ocean levels

Melting Ice layers on land might.

I'd ike to know howmany meters the ocean level will rise, when all of the antarctic ice layers have melted.
A non-biased, non-left, non-right, non-liberal, non-conservative 100% scientific source would be nice.
Last source I was shown, tried to explain to me the rise of ocean-levels was an ongoing (and possibly unstoppable) procedure :crazyeye: .
Though even a mentally handicapped person should understand ice stop melting when it's completely melted, some scientists tend to disagree..........


Allow me to do some math:
Total earth surface: 509.950.700 km²
Of which is 71% water: 362.064.997 km²
Antarctica has a surface of 63.000 km²

If we want a sealevel rise of 1 meter, we need 5747,1 meters of ice on Antartica......

Where the hell do I go wrong with my math?
I did this research in 5 minutes, yet some (left-wing) scientists come up with stories of meterS of sealevel rise........
 
10,000 to 20,000 years? Okay, I can accept that as being since the last true Ice Age. ;) The "current" warming trend is only about 600 - 800 years old though (remember the "little ice age", circa 1200AD?). :p

Anyway, I remember reading a science article on weather/climate back in the early '70s, and one thing it said still sticks in my mind: the early to mid 20th century experienced some of the *nicest* weather in recorded history, but the people who grew up during it thought it was "normal", and when weather patterns reverted back to true "normal", there would be hell to pay....
 
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