Seismologists G�ran Ekstr�m and Victor C. Tsai at Harvard and Meredith Nettles at the Lamont-Doherty Earth Observatory have published a report that shows that glaciers produce "glacial earthquakes" and that these quakes provide further evidence for global warming. Click on attachment (View in Google Earth ) for an overlay of the map and explanation of the symbols.

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"People often think of glaciers as inert and slow-moving, but in fact they can also move rather quickly," says Ekstr�m, professor of geology and geophysics at Harvard who will be moving to Lamont-Doherty in the spring. "Some of Greenland�s glaciers, as large as Manhattan and as tall as the Empire State Building, can move 10 meters in less than a minute, a jolt that is sufficient to generate moderate seismic waves."

As glaciers and the snow atop them gradually melt, water seeps downward. When enough water accumulates at a glacier�s base, it can serve as a lubricant, causing blocks of ice 10 cubic kilometers in size to lurch down valleys known as "outlet glaciers," which funnel all of Greenland�s glacial runoff toward the surrounding seas.

"Our results suggest that these major outlet glaciers can respond to changes in climate conditions much more quickly than we had thought," says Nettles, a postdoctoral researcher at Lamont-Doherty. "Greenland�s glaciers deliver large quantities of fresh water to the oceans, so the implications for climate change are serious. We believe that further warming of the climate is likely to accelerate the behavior we�ve documented."
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Although glacial earthquakes appear to be most common in Greenland, Ekstr�m, Nettles and Tsai have also found evidence of glacial earthquakes originating from mountain glaciers in Alaska and at glaciers located in ice streams among the edges of Antarctica.

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Source: http://www.ldeo.columbia.edu/news

For the full article describing the report CLICK HERE.

Another article. And yet another.

If you take a look in detail at this glacier which behaved consistently from 1950-995 you can see the recent retreat trimlines. You can see the surface meltwater that can feed through crevasses to speed the glacier flow. you can also note a new calving margin suggesting further retreat is imminent. This glacier drains nearly 10% of the Greenland Ice Sheet which is why it has been studied so intensively.

Thanks for this explanation which is a great help with the interpretation of glacier satelite images. Would you be able to predict the location of eskers based on glacier surface ice topography?

You should be able to do so. I have noticed in photographs where they are likely and then observed them 20 years later after glacier retreat. In the case of this glacier there will be no eskers, flow is too fast. You need a stagnant ice margin to generate eskers. i have only worked in Greenland on Jakobshavns Glacier, but given your question I looked in an obvious area and found first good locations for esker formation under the ice, and then noticed an esker beyond the ice margin. In Alaska I note two glaciers that are likely to form eskers. howevre, in valley regions like the Rendu, with time the Esker will often be buried by outwash plain sediments.

Again thanks, that is very helpful and interesting. The esker you show reminds me very much of the landforms I have seen in Canada. For many years I have done a lot of airphoto and satelite interpretation in Canada, of course all in deglaciated areas across the precambrian shield, with many land ice formed landforms like drumlins, eskers, kame complexes, and the various moraines.

My interest has been the melting of permafrost in peatland forms like palsa and peatplateausin in the southern part of the discontinous permfrost zone in Canada. It happens to be a part of the former Glacial Lake Agassis basin and has some impressive wave washed eskers and esker kame deltas.

www.geostrategis.com/p_mapm2.html

www.ecoinformatics.info

In the attached exmaple the esker kame complex is modified by wave action of glacila lake agassiz. Permfrost occusrs in about 5-10% of the peatlandforms. At its maximum probably around 25%

This is altering the topic a bit, as this note focusses on the impact of the Denali 7.9 magnitude earthquake in 2002 on the Black Rapids Glacier. The quake caused an entire mountain side to collapse and spread across the glacier.

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All over Greenland and the Arctic, rising temperatures are not simply melting ice; they are changing the very geography of coastlines. Nunataks � �lonely mountains� in Inuit � that were encased in the margins of Greenland�s ice sheet are being freed of their age-old bonds, exposing a new chain of islands, and a new opportunity for Arctic explorers to write their names on the landscape.

�We are already in a new era of geography,� said the Arctic explorer Will Steger. �This phenomenon � of an island all of a sudden appearing out of nowhere and the ice melting around it � is a real common phenomenon now.�

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The place-mark attachments show an area of Greenland where and island, once thought to be part of the mainland, has appeared. One overlay shows a 1986 photo of a "peninsula". Disabling the overlay shows it to be an island.

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Despite its remote location, the island would almost certainly have been discovered, named and mapped almost a century ago when explorers like Jean-Baptiste Charcot and Philippe, Duke of Orl�ans, charted these coastlines. Would have been discovered had it not been bound to the coast by glacial ice.

Maps of the region show a mountainous peninsula covered with glaciers. The island�s distinct shape � like a hand with three bony fingers pointing north � looks like the end of the peninsula.

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From The New York Times-January 16, 2007

Nice point Jumble. I took a look at a couple of Greenland glacier sites that I had looked at in satellite imagery back in the early 1980's for a different reason. Each of the noted locations indicate regions that are not surrounded by water yet, but likely will be. Now I will have to go back to those images if I can find them.

Thanks for all your work,mspelto!!
A great collection of potentially frightening indicators!
If there are any openings, sign me up for the NNI* club!


*No New Islands

Nice try, but this was known to be an island as far back as the 40s and 50s, with the expeditions of Dr. Lauge Koch. The aerial photographer, Hofer, published in 1957, clearly showing it as an island.

Hofer, E., 1957. Arctic Riviera, K�mmerly & Frey Berne Geographical Publishers, Berne, Switzerland, Distributed in the U.S. by Rand McNally & Co., Chicago, pp. 125.

What's more, the area lines up with the crevasse that runs the length of the atlantic. The most likely cause of warming in this area is increased volcanic activity.