Posted on 02/16/2006 9:27:29 PM PST by quantim
Sea levels are rising quicker than previously thought because the amount of water Greenland's glaciers are dumping into the Atlantic Ocean has almost doubled in five years, according to research to be published today.
Scientists who carried out the first comprehensive analysis of changing speeds of the glaciers on the world's largest island were shocked to discover that many have doubled in speed within the past decade.
Warmer temperatures are "lubricating" the glaciers and have driven a 150 per cent increase in the amount of ice they are delivering to the ocean between 1996 and last year. The latitude at which this is happening is moving north.
The researchers fear that as a result current estimates that sea levels will rise by up to 90cms during the 21st century could underestimate the problem.
While there have been previous isolated reports of particular glaciers speeding up, the research presented yesterday at the American Association for the Advancement of Science conference in St Louis is the first detailed study showing the effect is widespread across Greenland.
Eric Rignot, of Nasa's Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, the leading author of the study, said: "Climate change can work in different ways, but generally speaking, if you warm up the ice sheet, the glacier will flow faster.
"The southern half of Greenland is reacting to what we think is climate warming. The northern half is waiting but I don't think it is going to take long. If more glaciers accelerate farther north, especially along the west coast, the mass loss from Greenland will continue to increase well above predictions."
The Intergovernmental Panel on Climate Change has estimated that global sea levels will increase by 10-90cms over the next century. Last century they rose by 10-20cm. Previously models of the melting of the Greenland ice sheet have been based mainly on airborne laser altimetry and have suggested that while the interior is reasonably stable, the periphery was thinning, especially in areas where glaciers meet the sea.
Dr Rignot and colleagues set out to obtain accurate measurements to help to build a clearer picture of Greenland's current and future contribution to rising sea levels. They collected satellite data on the speeds of 27 glaciers and made estimates for two others.
The velocities of several large glaciers had doubled in recent years to 12km per year, making them among the fastest flowing in the world.
The scientists found that warmer air temperatures have increased the overall shrinkage of the Greenland ice sheet from 91 cubic km per year in 1996 to 138 cubic km per year in 2000 and to 224 cubic km per year in 2005.
About two-thirds of this was caused by the dumping of ice in the Atlantic by glaciers and so the ice loss attributable to glacier flow grew by 150 per cent from 60 cubic km a decade ago to 150 cubic km last year.
On this basis Dr Rignot, whose work is published in Science, concluded that Greenland's contribution to rising global sea levels increased from around 0.23mm per year in 1996 to around 0.57mm per year in 2005.
The Greenland ice sheet is 1.7 million sq km - a little smaller than Mexico - and three kilometres thick. If it melted completely sea levels would rise by seven metres
ummm it's hard to believe to see these logical constructions to somehow keep the attitude that global warming is not happening and burning of fossile fuel can't be the reason.
You have to be very ignorant these days to see past the observations. I thought it wasn't possible - but it is.
Lol - 'Advancing glaciers in greenland'. Dude they are melting down and then they slip into the ocean -yes that's advancing somehow - jeez.
Update:
Earth is warming - ice shields are melting. Noone seriously doubts that. And it's no 'contradiction' if the melting ice is slipping towards the ocean or the polar ice shields are growing. Melt some ice on your stove and open the deep freezer next to it and see what happens in the freezer.
CO2 is a very good reflector for heat radiation from earth. That's measurable. CO2 ammounts are increasing in the atmosphere and you can even calculate how much of this stuff is emitted by burning fossile fuels.
So the questions are not - are we taking influence on the global climate - but are we taking enough influence to increase average temperatures. Other factors like the sun or natural sorces of CO2 or methane might be even more of an influence.
So the man made influence might be insignificant - but it's not likely.
It's no question that man contributes to the warming.
90% of the earth's ice is in Antarctica, where the ice is GROWING, Dude.
Ya think?
Okay, I was with you until the following:
"So the man made influence might be insignificant - but it's not likely.
It's no question that man contributes to the warming."
Have you got any proof of this whatsoever?.
yup.
we burn fossile fuel - that produces CO2 and H2O the first is a highly efficient reflector of heat radiation - thus we contribute via the so called green -house effect to the warming of the globe.
This is known long time and not even discussed anymore.
The controverse is about the magnitude and significance of this contribution.
read again the part with the freezer.
might very well be.
why do you reckon that ?
remember:
- there are crevaces in glaciers
- water doesn't flow up
exactly my opinion
It's kinda hard to politicize physical measurements.
so that's the reason for the yellow colour ?
I know.. and it's even worse on Mars where the greenhouse gasses are doing some serious heating. Yes that must be the cause of the coincidental heating of Mars. What else could it be?
Dude the Greenland glaciers are 2 KM deep so you say the central part has melted and just the edge is slipping into the ocean?
ok - let's end this discussion and just go there and have a look - you ready packing ?
can't trust these geologists today - can ya ?
Should be good for Greenland farmers!
ahh no worries - it's done every day.
HEADLINE FROM FEB. 17, 1150 A.D.
What about astronomers? Sunspots? Wobble of Earth's axis? Oh I get it, these are the things that cause ice ages...
"It's kinda hard to politicize physical measurements."
Tell me that you're kidding!
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