Posted on 03/24/2006 4:23:14 PM PST by blam
Glacial earthquakes rock Greenland ice sheet
12:36 24 March 2006
NewScientist.com news service
Jeff Hecht
A rapid increase in “glacial earthquakes” – caused by sudden large movements of glaciers – over the past few years indicates that warmer temperatures will destroy the Greenland ice sheet faster than expected, a new study warns.
Surface meltwater is not dribbling away, as if from a giant ice block melting slowly, but is seeping through cracks to the bottom of the glacier. Once there it forms a layer that "helps lift the glacier up from the rock" so it flows faster to the sea, says seismologist Göran Ekström at Harvard University, US, who led the study.
He discovered the glacial quakes three years ago, when looking for unusual earthquakes, and traced them to slips within the ice. And the quakes can be substantial: a 10-metre slip of an ice slab roughly the size of Manhattan Island, and as tall as the Empire State building, causes a magnitude-5 quake on the Richter scale.
When the team analysed glacial seismic records back to 1993, they found a striking increase in the number of quakes recorded in recent years. All 136 of the best-documented slips were traced to glaciated valleys draining the main Greenland ice sheet. A handful of others occurred in Alaskan glaciers or on Antarctica.
Ekström reports that quakes ranged from six to 15 per year from 1993 to 2002, then jumped to 20 in 2003, 23 in 2004, and 32 in the first 10 months of 2005 – matching an increase in Greenland temperatures.
Falling apart The finding adds to evidence that the Greenland ice sheet is far more vulnerable to temperature increases than had been thought. Models that treated glaciers like giant ice cubes had predicted very slow melting. But recent studies of Greenland glaciers have shown much faster effects when meltwater causes glaciers to slip easily over rock.
"Within a few years after temperature warms, you get a big increase in discharge," says Ian Joughin of the polar science center at the University of Washington in Seattle, US. "If temperature rises two or three degrees in Greenland, things are going to start falling apart," Joughin told New Scientist. Antarctica is not as sensitive to rising air temperature because it is too cold for surface melting, which accounts for about half the mass lost from the Greenland ice sheet.
Other ominous news comes from a pair of new studies examining sea level and glaciation 129,000 years ago. This was during the last interglacial period, when the Arctic was as warm as it is expected to be by 2100 – when it is expected to be at least 2.2°C (4°F) warmer than present. Palaeontological evidence, examined by Jonathan Overpeck at the University of Arizona, US, and colleagues, indicates that sea levels were 4 to 6 metres higher than they are today, and some of that water came from melting of the Antarctic ice sheet.
Journal reference: Science (vol 311, pps 1756, 1747, 1751)
Karl Rove Controls The Weather bttt
Where's the hockey stick graph to prove this?
/sarcasm
You all can joke about this, but it really will have an impact on our weather. All of that fresh water, hitting and diluting the salt water is not a good thing. I don't care if it is a natural occurence, or if it is man made, the end results will not be pretty. Don't mess with mother nature.
"This was during the last interglacial period, when the Arctic was as warm as it is expected to be by 2100 – when it is expected to be at least 2.2°C (4°F) warmer than present"
So much for the theory that man is causing this global warming. This is just the periodic warming period that is a prelude to a plunge back into an ice age and normalcy.
He read an excerpt from Newsweek magazine dated April 28, 1975. Scientists urged the melting of the polar ice caps in an effort to fend off the imminent 'Global Cooling' which threatened to shorten the global growing periods, wipe out grain crops and cause worldwide starvation.
Now we do as they said, and we have to stop? I wish they'd make up their minds.
Denmark owns Greenland?
Thinking of them myself - I'm up north and keep hoping for a return to the days of weather the Vikings enjoyed for some 350 years....wouldn't mind that cycle coming around again///
I sm so confused. How can a natural occurence mess with mother nature? Seems mother nature must have some control over natural occurences.
I just love the erudite scientific nature of your comment. Certainly better thought out than most global warming disaster scenarios.
Ecclesiastes 1:4 One generation passeth away, and another generation cometh: but the earth abideth for ever.
Ice cubes for all.
Now, LilyBean...you don't know that. We've all heard about fresh water cutting off the Atlantic gulfstream, but all these dire predictions about New York flooding are little more than scientific guesses.
Many or all are based upon computer modeling, and we hear scientists don't have enough data to do it properly, so they just make stuff up.
This is awesome. Mother Nature at her best. Fascinating.
You contradict yourself. If you are willing to admit that it might be a natural occurrence, why do you end with "Don't mess with mother nature? If it's natural then it IS mother nature, making it wholesome and groovy.
Just nature keeping itself in balance.
Ahem, this IS mother nature. Don't let your pride so delude yourself that Man possesses powers much more than the level of "puny."
Global Cooling Is Going To Kill Us All! Newsweek article in PDF form.
Global warming or global cooling?
The Truth About Global Warming
There are other articles at Beck's site, some interesting reads. GLENN BECK.COM
You have no proof that the outcome will be bad. It might just as well be good- more plant growth, higher oxygen levels, more rain for arid areas, warmer climates for cold areas that cannot be farmed, etc.
If this phenomena is a natural process, as I believe, then it has occurred millions of times in the past billions of years. Yet the earth, and the life on it, has survived and thrived. So why is it assumes the outcome will be disaster?
Sell more papers, click-thrus...hyperbolic hysteria to the gullah-bull on glow-ball warning.
Thanks. That's my take on it too.
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