WASHINGTON (Reuters) -- Glaciers once held up by a floating ice shelf off Antarctica are now sliding off into the sea -- and they are going fast, scientists said on Tuesday.
Two separate studies from climate researchers and the space agency NASA show the glaciers are flowing into Antarctica's Weddell Sea, freed by the 2002 breakup of the Larsen B ice shelf.
Writing in the journal Geophysical Research Letters, the researchers said their satellite measurements suggest climate warming can lead to rapid sea level rise.
The teams at NASA's Jet Propulsion Laboratory in Pasadena, California, the National Snow and Ice Data Center at the University of Colorado in Boulder, and NASA's Goddard Space Flight Center in Greenbelt, Maryland, said the findings also prove that ice shelves hold back glaciers.
Many teams of researchers are keeping a close eye on parts of Antarctica that are steadily melting.
Large ice shelves in the Antarctic Peninsula disintegrated in 1995 and 2002 as a result of climate warming. But these floating ice shelves did not affect sea level as they melted.
Glaciers, however, are another story. They rest on land and when they slide off into the water they instantly affect sea level.
It was not clear how the loss of the Larsen B ice shelf would affect nearby glaciers.
But soon after its collapse, researchers saw nearby glaciers flowing up to eight times faster than before.
"If anyone was waiting to find out whether Antarctica would respond quickly to climate warming, I think the answer is yes," said Theodore Scambos, a University of Colorado glacier expert who worked on one study.
"We've seen 150 miles (240 kilometers) of coastline change drastically in just 15 years."
The affected area is at the far northern tip of the Antarctic, just south of Chile and Argentina. Temperatures there have risen by up to 4.5 degrees Fahrenheit (2.5 degrees C) in the past 60 years -- faster than almost any region in the world.
In the past 30 years, ice shelves in the region have lost more than 5,200 square miles (13,500 sq km) of area.
"The Larsen area can be looked at as a miniature experiment, showing how warming can dramatically change the ice sheets, and how fast it can happen," Scambos said in a statement. "At every step in the process, things have occurred more rapidly than we expected."
But not all the melting in the Antarctic can be seen as a "miniature experiment."
The Ross ice shelf, for example, is the main outlet for the West Antarctic Ice Sheet, with several large glaciers that could, if they melted completely, raise sea levels by 16 feet (5 metres).
"While the consequences of this area are small compared to other parts of the Antarctic, it is a harbinger of what will happen when the large ice sheets begin to warm," Scambos said. "The much larger ice shelves in other parts of Antarctica could have much greater effects on the rate of sea level rise."
Who cares about terrorists and campains... the freaking sea is about to rise 16 feet... How are we going to save our costal cities? Build walls?
Posts: 4953 | Registered: Jan 2004
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Very good... hehehe.. but seriously... even if this takes decades or a century what will happen to civilization?
Posts: 4953 | Registered: Jan 2004
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posted
This won't be the first time the world's climate has dramatically changed and life had to adapt. It is sad if it is our fault though.
Posts: 7050 | Registered: Feb 2004
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quote: Who cares about terrorists and campains... the freaking sea is about to rise 16 feet... How are we going to save our costal cities? Build walls?
Eh...they're all Democrat/Liberals...God's Second Flood? (this is meant as a joke so please take it as such.)
posted
One day, everyone's going to wake up with a collective oops when they step out of bed into soggy slippers.
Posts: 8473 | Registered: Apr 2003
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posted
I read a Clive Cussler book called Atlantis Found that talked about some rich folks building this gigantuan life sustainable boat, and then trying to blow up part of a glacier in Antarctica so the world drowned.
quote:"Imagine," Tyler said, "stalking elk past department store windows and stinking racks of beautiful rotting dresses and tuxedos on hangers; you'll wear leather clothes that will last you the rest of your life, and you'll climb the wrist-thick kudzu vines that wrap the Sears Tower. Jack and the beanstalk, you'll climb up through the dripping forest canopy and the air will be so clean you'll see tiny figures pounding corn and laying strips of venison to dry in the empty car pool lane of an abandoned superhighway stretching eight-lanes-wide and August-hot for a thousand miles."
posted
In theory shouldn't global warming lower the sea level? Doesn't water after all expand in cold decrease in warmth? Isn't this why deserts are expanding and inland lakes are dring up? Why not airlift massive ice blocks and use them to refill inland waterways? Or we could use them to make aircraft carriers like Churchill wanted to during World War II although I can't find the link.
Posts: 3446 | Registered: Jul 2002
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posted
Water is densest somewhere just above freezing. It expands when it freezes and expands when it warms up.
Ice melting in the ocean doesn't directly raise the sea level, although the same rising tempatures that melts the ice may cause therma expansion of the water.
Ice melting on land is a big problem. Remember, the land bridges existed when the ice age was advanced, because sea level went down.
posted
The expansion and compression of water is an extremely small effect, particularly for the degree or two that global warming will heat it. The melting of Antarctic glaciers, on the other hand, is a large effect.
Posts: 10645 | Registered: Jul 2004
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posted
Did anyone see the episode of Harvey Birdman where the Jetsons come back in time to complain about global warming?
Posts: 1401 | Registered: Jun 2004
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I'm looking forward to it! Always liked hot weather! This area was all shallow seas during the Cretaceous. I'm counting on having beachfront property soon. All you Florida people can move up here! Posts: 6246 | Registered: Aug 2004
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Look on the bright side: Antartica might become the new popular resort area if it warms up enough!
Posts: 862 | Registered: Oct 2003
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Since the sea level so far has seemed to be steadily rising instead of tsunami-like flooding of the coasts, I think that people will keep getting their houses flooded and the coastline will gradually move back. Lots of property damage, but no real danger. California will be interesting, though, becasue the estimates I've seen say that it will pretty well be under water. Its such a standpoint that I'm not sure where it will go. Vegas? Ocean pod studios?
Posts: 1777 | Registered: Jan 2003
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How come this isn't a problem for us though. "Oh, we'll move inland."
Won't it change everything? Climates; forest will become desert etc. The land will be more crowded. Are we just assuming there's nothing we can do? Or is this a fluff thread which everyone is taking half-seriously but really they're worried about it?
I think it's serious. I havewn't had a chance to visit all the land that's going to end up underwater and if it disappeares that's it. Gone forever, left only in photographs.
quote:And now all those lands lie under the wave. And I walk in Ambaróna, in Tauremorna, in Aldalómë. In my own land, in the country of Fangorn, Where the roots are long, And the years lie thicker than the leaves In Tauremornalómë.
posted
Ok the reason why icebergs don't matter is the principle of displacement, directly corellated to density and good old Archimedes. It's the same reason why boats float. You see, the iceberg (density around 0.92 g/cm^3) is less dense than salt water (density around 1.00 g/cm^3).
Any floating iceberg or ice shelf in the ocean is already displacing 0.92 grams of water. So when an iceberg breaks off from an ice shelf and melts there is no huge net volume change in the ocean rising, because it's only going up by 0.08 cm^3/gram of water, which in something as vast as our oceans is pretty insignificant.
There is a minor volume change based on the difference between the densities of saltwater and freshwater, which would impact things slightly if the entire Arctic ice shelf melted.
quote: Arctic Ice Deluge?
One concern that most people have with regard to the melting of the Arctic Ice Cap is the eventual flooding of the land masses. What is commonly misunderstood is that the Arctic Ice Cap is relatively thin, about 10 feet thick on average. And about 90 % of that is already displacing the water (taking up space that would otherwise be occupied by water). Thus, even a complete melting of the Arctic Ice Cap would only result in a small increase in sea water level.
However, this is not the case in the Antarctic. Antarctica as we all know from a globe, is a continent. The ice actually sitting on the land mass there is *not* displacing seawater already. But the stuff on the ice shelves around it is. So as it says in the article Telperion posted, its not the actual ice shelves breaking up that is going to raise the water levels. It is the additional sliding of ice from continental glaciers that wasn't already in the ocean that will eventually raise it. And the ice cap in Antarctica is much much thicker than the stuff in the Artic.
From the same source as above:
quote: On the Opposite End of Earth
Antarctica, which covers the geographic South Pole, is itself covered with thick ice sheets. The average ice thickness is about 1.5 miles with some parts reaching as deep as three miles. Antarctica's ice shelves are also melting, for the same reasons associated with the melting of the Arctic Ice Cap, but not as dramatic. The melting of the Antarctic ice shelves has resulted in the calving of some of the largest icebergs ever known to exist, such as the series of icebergs that broke off from the Ross Ice Shelf in the spring and summer of 2000
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Yeah, but for all that to happen in the Antarctic, all that ice would have to fall up.
Sheesh. All this worrying, and for what? Nothing! Nothing, I tell you! Please look away, get back into your SUV's and drive away...
Posts: 1862 | Registered: Mar 2000
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posted
This is a serious subject but we don't have enough of a handle on it scientifically to really know what is happening or what to do about it.
The earth's climate is unstable. We know that for the last hundred thousand years or so, there have been ice ages at nice 10,000 year intervals. The periodicity of this phenomenon is very clear. Why? We don't know. How does it start? We're not sure. It's possible that a warming phase begins each ice age. Oh and by the way, the next ice age is due to start about now (give or take 1000 years).
We think it makes sense that digging up all that carbon and burning it as fossil fuels increases the CO2 in the atmosphere which will warm the earth. However, the jury is really still out on whether the earth is actually warming and certainly we're not positive of the cause and effect.
I read the papers and here's what they did. They collected temperature records, all that we have in history, and compared them over time. The raw data shows that the earth is getting colder. Huh? That can't be right. Oh yeah! The thermometers on ship's logs now ride deeper below the surface. In the olden days they were right on top, we think. So let's correct so much for that. Then one by one they thought of other correction factors. Until finally they come up with this number of 1/2 degree warming in the last century. Okay that sounds reasonable. Now we can quit looking for other correction factors. I just don't buy it. Nothing like conclusive to me.
And think what we have to do to fix this. What would it take to quit burning fossil fuels? Basically we have to all live as hunter gatherers again. The world can support some 10 million hunter gatherers. The other 6 billion people would have to die. Who volunteers?
This is a very quick simplistic version of all these arguments. But when you dig deeper the basic conclusions hold up. Climate on earth is unstable. We don't know what is happening to our climate or why, or how to fix it if it's bad. It's helpful to discuss all the options and responses, and all the alternative scenarios, and of course we want to continue to study this whole field, but so far nobody has come up with anything compelling that we should be doing.
My own feeling is that the path forward for humanity must lie with greater understanding and more use of technology, not less. Fossil fuels are a temporary energy source for humanity in any case. Fission reactors are another one that are in use now, and will definitely make a comeback if fossil fuel prices get high enough. Fusion research still hasn't resulted in working reactors after all this time, and so we can't count on any breakthroughs there, though something like a cheap cold fusion process could surely save the planet. At this point I think we just have to keep going and see what happens.
What we really need to be worrying about and spending money on is an asteroid defense system.
I remember hearing somewhere that the continent of Antartica will actually raise up a significant amount (I remember something like several hundred feet) if all the ice were removed, based on the weight being removed.
First, is this true?
Second, could this have earthquake-inducing effects?
Yes, the continent would concievably raise some amount. For two reasons. First, the geologic reason. The underside of the Earth's crust actually mirrors, to some extent what's going on on top, due to buoyancy issues with the mantle. So if you remove that much ice, you suddenly have less mass pressing down, and there is a net force exerted upward on the crust, so over time (and it will take a long time) the land will rise up to reach equilibrium. The second reason is a matter of soil and rock mechanics. Soil and rock actually compress under increasing stress (weight), and will rebound, though not entirely elastically (in other words it won't go back to the way it was). So with the removal of that weight, the ground and rock will expand, raising the ground surface.
Earthquakes are likely a given, since the stress on fractures would decrease and with less pressure holding the faults in place (less frictional force), they are going to slip.
Posts: 609 | Registered: Apr 2003
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quote: And think what we have to do to fix this. What would it take to quit burning fossil fuels?
We would not neccesarily have to go cold-turkey on fossil fuels. More effiency would help cutback CO2. Scrubbers and other fuels would limit CO2 and other greenhouse gases that trap heat. Alternate energy sources could be developed at an accelerated rate. The Kyoto accords were a 1st step at tackling the issue globally.
President Bush's response: No, thanks, I'll wait until my slippers are wet.
Posts: 6316 | Registered: Jun 2003
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quote:NFL, here's a web-page about that ice berg carrier-- WWII iceberg carrier
WWII had so many crazy ideas!
Heh. Harry Turtledove has written a series of fantast books that still are bascially a re-telling of WWII in this fantasy setting, inlcuding the Holocaust, nuclear weapons, and all of it. And one of the sides developed iceberg "dragon farms" that they sailed around -- and they are called "Habbakuks" in the books. didn't realize he'd stolen the name directly.
And they're pretty good books too.
Posts: 1323 | Registered: Aug 2001
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The dirt from my best friend. I e-mailed her the link and asked Dagonee's question.
quote: Re: Planetary science/geology question
You folks seem to have a pretty good handle on most of the scientific issues. Happy camper is right, the continent would rebound somewhat if all the mass on top of it was removed. I'm not at all convinced that it would directly lead to earthquakes though; I would think it would happen too slowly to really trigger anything. And if it does, then maybe some local ones but there's hardly anyone there, so who cares? But I'm not going to contradict Happy Camper.
THere's only one thing I didnt' see discussed there. I think the big issue regarding global warming is not that coastal cities are going to get their feet wet. The biggest problem will be that the major farming/ranching areas in the world are going to move. The US midwest will become a desert and canada will have all the good farming. I can imagine big problems in the china/russia region too.
Obviously the best solution is to rid ourselves of our dependence on this measely planet and go colonize Mars. But someone already mentioned the moon, so I'm not even bringing up anything new there either.
-Gwen
Have I ever mentioned how cool Gwen is? Her new husband is actually the first person you will find if you google "plasma grape". He's cool too.
quote:You folks seem to have a pretty good handle on most of the scientific issues. Happy camper is right, the continent would rebound somewhat if all the mass on top of it was removed. I'm not at all convinced that it would directly lead to earthquakes though; I would think it would happen too slowly to really trigger anything. And if it does, then maybe some local ones but there's hardly anyone there, so who cares? But I'm not going to contradict Happy Camper.
This is true. I'm not a geologist remember. [not fact, merely informed speculation]What I said would probably be true if the mass were to be instantaneously removed. And it might lead to small quakes as the mass slowly diminished. It also depends on the depths of the quakes. Very deep ones would likely feel very little difference, but shallow faults would be more affected. And actually it might lead to a decrease in the intensity of any given earthquake, since there would be less pressure and would take less stress to cause a slip.[/not fact, merely informed speculation]
Posts: 609 | Registered: Apr 2003
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quote: you'll climb the wrist-thick kudzu vines that wrap the Sears Tower
This will probably happen. Kudzu is some freaky stuff. It covers entire hillsides--trees and houses included. I was thinking that if there was ever a hybrid of kudzu and aspen, it could withstand colder temperatures and take over every square inch of the planet. Posts: 4089 | Registered: Apr 2003
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posted
HC I'll refer Gwen back to this when I'm sober. I want to know, whether gradual, or rapid, if melting the ice and the continent raising would change the magma flow underneath and thus effect somewhere else. Like if the magma bulges there to equalize the forces will all of the other continents drop even more because there's less magma supporting them. Or maybe there is too much magma overall and the difference is negligible.
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