Posted on 02/16/2006 4:54:22 PM PST by blam
Greenland ice swells ocean rise
By Paul Rincon
BBC News science reporter, St Louis
Kangerdlussuaq Glacier "drains" about 4% of the ice sheet
Greenland's glaciers are sliding towards the sea much faster than previously believed, scientists have told a conference in St Louis, US.
It was thought the entire Greenland ice sheet could melt in about 1,000 years, but the latest evidence suggests that could happen much sooner.
It implies that sea levels will rise a great deal faster as well.
Details of the study, by Nasa and University of Kansas researchers, are also reported in the journal Science.
The comprehensive analysis found that the amount of ice dumped into the Atlantic Ocean has doubled in the last five years.
If the Greenland ice sheet melted completely, it would raise global sea levels by about 7m.
Greenland's contribution to global sea level rise today is two to three times greater than it was in 1996.
Sleeping giant
"We are concerned because we know that sea levels have been able to rise much faster in the past - 10 times faster. This is a big gorilla. If sea level rise is multiplied by 10 or more, I'm not sure we can deal with that," co-author Eric Rignot, from the US space agency's (Nasa) Jet Propulsion Laboratory in California, told the BBC News website.
Previous estimates suggested it would take many hundreds of years for the Greenland ice sheet to melt completely. The new data will cut this timescale, but by how much is uncertain.
It takes a long time to build and melt an ice sheet, but glaciers can react quickly to temperature changes
Dr Eric Rignot, Nasa "It depends on how fast the glaciers can go and how sustainable the acceleration can be," said Dr Rignot.
He added: "It takes a long time to build and melt an ice sheet, but glaciers can react quickly to temperature changes."
In 1996, Greenland was losing about 100 cubic km per year in mass from its ice sheet. In 2005, this had increased to about 220 cubic km. By comparison, the city of Los Angeles uses about one cubic km of water per year.
Rising surface air-temperatures seem to be behind the increases in glacier speed in the southern half of Greenland since 1996; but the northward spread of warmer temperatures may be responsible for a rapid increase in glacier speed further north after 2000.
Satellite monitoring
Over the past 20 years, the air temperature in south-east Greenland has risen by 3C.
Warmer temperatures cause more surface melt water to reach the base of the ice sheet where it meets the rock. This is thought to serve as a lubricant, easing the glaciers' march to the sea.
Helheim Glacier loses the equivalent of about half a football field a day
The study's results come from satellites that monitor glacier movement from space.
Rignot and colleague Pannir Kanagaratnam, from the University of Kansas, built up a glacier speed map from the data for 2000 and then used measurements from 1996-2005 to determine how glacier velocity had changed in the last decade.
The researchers plan to continue their monitoring of the Greenland glaciers using satellite data.
The Greenland ice sheet covers 1.7 million sq km and is up to 3km thick.
The scientists described their results at the annual meeting of the American Association for the Advancement of Science.
From the article it sounds as though there is close to 5M cubic km of ice left which would take about 22,000 years to melt at 220 cubic km per year.
When it gets to 2,000 cubic km per year, let me know and I'll start planning.
However, the last data I saw (U. Michigan study) indicated that the ice was growing in the interior, while melting near the sea -- for about a net-zero effect.
It snows there all the time. When the snow lands on land, it stays there and is eventually compressed into ice by the weight of the subsequent snow fall. With global warming, it's all suppose to melt. Same with Oetzi, the Ice Man, you mentioned.
Nice theory, but it won't wash.
Amid a flood of new data, it seems aquifers are soaking it up, and the increased sponge populations are sucking it in.
If any of these people were truly worried, they'd be pouring boxes of Jello on it, to stabilize it.
I was under the impression that ice that is floating in water that melts does not change the water level. I thought this would be due to it just being a weight thing. 50 gallons of water weighs the same as 50 gallons of ice. The ice may float because it expands during freezing. Oh hell I am confused!
The Greenland Ice Cap rests mostly upon solid ground above sea level.
A perhaps not insignificant factor may be that the Vikings coplonies were Christian, supported priests, and the priests forbid the use of fur clothing. They said only savages wore fur.
Those PETA predecessors (don't evenm start flaming - the PETA crack is a joke)caused their flock to use wool which is a poor substitute for fur. The natives had lots of marine mammal and fish to eat and stayed warm in their furs.
Meamwhile, the Vikings went hungry, chilled out to the point that the females and the young died far faster than they could be replaced.
Then the few survivors left.
Moral: Take your knowledge where you find it & don't let your dogma negatively impact yout karma.
They starved because they didn't eat fish.
Darn... how could I have forgotten about Jello??? I hereby nominate you to become one of our exalted resident climate experts. After all, if networks can find them, why can't we have them? Trouble is, the job doesn't pay much.
I bow in your general direction. :-)
Do you have any idea how much water you would have to add to the worlds "contiguous Oceans to increase the level even a fraction of an inch????? What BS!
Sorry, Doc, the article is correct. To see this, use the following facts:
Multiplying together the quantities in #3 and #4, we find that the total volume of the Greenland ice sheet is approximately 2.55 million cubic km. Now we use the following proportion:
As the current average depth of the oceans is to the current volume of the oceans, so is the post-Greenland-melt average depth of the oceans to the post-Greenland-melt average volume of the oceans.
If we let x stand for the increase in depth (in km) of the oceans produced by the Greenland melt, then our proportion looks like this:
4 / 1370 = (4 + x) / 1372.55
Solving for x, we find that
x = 0.0073 km (approximately)
Convert this to meters by multiplying by 1000, and it follows that the increase in depth of the oceans produced by the melting of the Greenland ice sheet is roughly 7.3 meters. Call it 7 meters as a round number. This is the same number mentioned in the article.
Thanks for your discussion of Paul Ehrlich. I'm a child of the 1970s -- you know, solar energy, Three Mile Island, smiley faces, and all that. It took me half a lifetime to get over all the dementia. (As a kid, I did make good cash waiting in gas lines for the neighbors...).
So many parallels to the 1970s just now -- and they all fall short. The difference is in our leadership, which today fails to give in, as did our leaders of the 1970s. So I'm hardly surprised that Ehrlich has resurfaced. And I'm hardly surprised -- and no less saddened for it -- that it was Atlantic Monthly that dug him up. Such promise the magazine had under Michael Kelly. The magazine has fallen hard since he died. (Fallows has taken over, again.)
Ehrlich is like the investor who thinks he's made a million bucks because, like the broken clock, his position finally caught its moment. And like that man, he thinks because he's right right now (for once) he'll be right hereafter. The problem is that Ehrlich is not predicting current commodity prices, he's going Hail-Mary short on 'em for well beyond today. Once again, he'll get his ass kicked.
The earth's radius is a tad under 6400 km. The surface area of a sphere is 4*Pi*r^2, so the area of the earth is 500 million km^2.
70% of that is water, so the area of the oceans is 350 million km^2
The area of the Greenland ice sheet is 1.8 million km^2. It's up to 3 km thick, but let's say the average thickness is 1.5 km. If it melted, it would give rise to a depth of water of 1350 m over Greenland (because ice contracts about 10% as it melts). Spread this 1.8 million km^2 area of water over an ocean area of 350 million km^2, and you get water to a depth of 1350m X 1.8/350, or 7 m.
Moral: before you rant, do the math.
Different method, same result. I guess that means we're right!
(laughing) As soon as I saw Doc's post, I decided to see for myself. I see that you did, too! Nice work.
Iceland's population may be a bit different from the Norwegian population when it comes to eating fish since most of their ancestry comes from Irish slaves Vikings brought to the island. In Norway, there's a less than 2% incidence of seafood allergy or intolerance in the population. In the rest of humanity, there's a 49% incidence of seafood allergy or intolerance in the population.
To the degree the Greenland population had Norwegian ancestry, they could eat fish, and to a far greater degree than an average human population anywhere else.
What happened is very simple ~ Greenland's climate was deteriorating, but it was a Fimbul Winter (a year without a summer) that destroyed the colonists.
It's believed it was a multi-year Fimbul Winter that affected most of Northern and Western Europe circa 538-541 and brought on the Dark Ages.
BTW, had fish for dinner.
Where did they go?
Hey, thanks! I'll take the position, on condition I can set my own salary, then donate it back, as a charity deduction! Shhhhh! Don't tell the IRS it's a scam!
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.