NASA Study Shows Greenland, Antarctic Melt Accelerating Rapidly - Some Ice Sheets Already In Runaway

[hatrack]

WASHINGTON – New satellite information shows that ice sheets in Greenland and western Antarctica continue to shrink faster than scientists thought and in some places are already in runaway melt mode. British scientists for the first time calculated changes in the height of the vulnerable but massive ice sheets and found them especially worse at their edges. That's where warmer water eats away from below. In some parts of Antarctica, ice sheets have been losing 30 feet a year in thickness since 2003, according to a paper published online Thursday in the journal Nature.

Some of those areas are about a mile thick, so they've still got plenty of ice to burn through. But the drop in thickness is speeding up. In parts of Antarctica, the yearly rate of thinning from 2003 to 2007 is 50 percent higher than it was from 1995 to 2003. These new measurements, based on 50 million laser readings from a NASA satellite, confirm what some of the more pessimistic scientists thought: The melting along the crucial edges of the two major ice sheets is accelerating and is in a self-feeding loop. The more the ice melts, the more water surrounds and eats away at the remaining ice.

"To some extent it's a runaway effect. The question is how far will it run?" said the study's lead author, Hamish Pritchard of the British Antarctic Survey. "It's more widespread than we previously thought."

The study doesn't answer the crucial question of how much this worsening melt will add to projections of sea level rise from man-made global warming. Some scientists have previously estimated that steady melting of the two ice sheets will add about 3 feet, maybe more, to sea levels by the end of the century. But the ice sheets are so big it would probably take hundreds of years for them to completely disappear. As scientists watch ice shelves retreat or just plain collapse, some thought the problem could slow or be temporary. The latest measurements eliminate "the most optimistic view," said Penn State University professor Richard Alley, who wasn't part of the study.

EDIT

http://news.yahoo.com/s/ap/20090923/ap_on_sc/us_sci_big_melt;_ylt=AnR7FROfNJ..PYL_DszYfYQPLBIF;_ylu=X3oDMTJnbDN2cmtuBGFzc2V0A2FwLzIwMDkwOTIzL3VzX3NjaV9iaWdfbWVsdARjcG9zAzEEcG9zAzEEc2VjA3luX3RvcF9zdG9yeQRzbGsDbmFzYWRhdGFncmVl

[OKIsItJustMe]

1. Press Release - Lasers from space show thinning of Greenland and Antarctic ice sheets

http://www.antarctica.ac.uk/press/press_releases/press_release.php?id=989

Press Release - Lasers from space show thinning of Greenland and Antarctic ice sheets

Issue date: 23 Sep 2009
Number: 09/2009

The most comprehensive picture of the rapidly thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets has been created using satellite lasers. The findings are an important step forward in the quest to make more accurate predictions for future sea level rise.

Reporting this week in the journal Nature researchers from British Antarctic Survey and the University of Bristol describe how analysis of millions of NASA satellite measurements* from both of these vast ice sheets shows that the most profound ice loss is a result of glaciers speeding up where they flow into the sea.

The authors conclude that this ‘dynamic thinning’ of glaciers now reaches all latitudes in Greenland, has intensified on key Antarctic coastlines, is penetrating far into the ice sheets’ interior and is spreading as ice shelves thin by ocean-driven melt. Ice shelf collapse has triggered particularly strong thinning that has endured for decades.

Lead author Dr Hamish Pritchard from British Antarctic Survey (BAS) says,

“We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline — it’s widespread and in some cases thinning extends hundreds of kilometres inland. We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise.”

The scientists compared the rates of change in elevation of both fast-flowing and slow-flowing ice. In Greenland for example they studied 111 fast-moving glaciers and found 81 thinning at rates twice that of slow-flowing ice at the same altitude. They found that ice loss from many glaciers in both Antarctica and Greenland is greater than the rate of snowfall further inland.

In Antarctica some of the fastest thinning glaciers are in West Antarctica (Amundsen Sea Embayment) where Pine Island Glacier and neighbouring Smith and Thwaites Glacier are thinning by up to 9 metres per year.

ENDS

…

[OKIsItJustMe]

2. Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08471.html

Letter

Nature advance online publication 23 September 2009 | doi:10.1038/nature08471; Received 23 October 2008; Accepted 28 August 2009; Published online 23 September 2009

Extensive dynamic thinning on the margins of the Greenland and Antarctic ice sheets

…

This serves as a good reminder of how slowly the wheels of the peer review process can turn (i.e. the paper was received almost a year ago…)

[OKIsItJustMe]

5. “it is so strong that it could not have been sustained previously without the glaciers melting away”

http://www.independent.co.uk/environment/climate-change/ancient-glaciers-are-disappearing-faster-than-ever-1792274.html

…

Areas around the Greenland coast are hotspots of glacier thinning – in some cases the glacier surface level is dropping at a rate of half a metre per year, while in others it is a remarkable rate of a metre and a half.

It is the first time that a comprehensive view of the rate of thinning – and thus ice loss – all the way around the coast has been made possible. It has been put together by Hamish Pritchard and his colleagues from the British Antarctic Survey and the University of Bristol, by analysing millions of measurements from Nasa's high-resolution ICESat (Ice, Cloud and Land Elevation Satellite).

Launched in January 2003, ICESat examines changes in the world's ice and land masses. The satellite's lasers have measured the surface elevation of the Earth's ice sheets with unprecedented accuracy – and thus picked up how they are changing.

"The fact that the changes are so large is alarming, and you wonder how far they will go," Dr Pritchard said. "The thinning effect must be relatively recent, as it is so strong that it could not have been sustained previously without the glaciers melting away."

…

[OKIsItJustMe]

6. Strange… I recommended this story earlier…

I believe we do have mice…

[hatrack]

7. Strange, no?

Here in the crisp, clean digital pseudo-world, little irritating mice. Hmm.

[XemaSab]

3. As I walk alone, I wonder... what went wrong?

http://www.youtube.com/watch?v=8TLLcvWeiKw&feature=related

[OKIsItJustMe]

4. I believe that's the first time that song has ever brought me close to tears…

Context is everything…

[earth mom]

8. Where is Al Gore in all this? Why isn't he meeting with Obama right now?!!!! nt

[defendandprotect]

9. k i c k

[jeffreyi]

10. yikes. I think I need a Hatrack puppy break....

[kestrel91316]

11. I'm sure glad there's no such thing as global warming. We can safely ignore this news.

[joshcryer]

12. Kick.