Permafrost Melt Fuels Rapid Growth In Arctic Alaska's Lake Zone

[hatrack]

"The thousands of oval lakes that dot Alaska’s North Slope are some of the fastest-growing lakes on the planet. Ranging in size from puddles to more than 15 miles in length, the lakes have expanded at rates up to 15 feet per year, year in and year out for thousands of years. The lakes are shaped like elongated eggs with the skinny ends pointing northwest.

How the lakes grow so fast, why they’re oriented in the same direction and what gives them their odd shape has puzzled geologists for decades. The field of lakes covers an area twice the size of Massachusetts, and the lakes are unusual enough to have their own name: oriented thaw lakes. “Lakes come in all sizes and shapes, but they’re rarely oriented in the same direction,” said Jon Pelletier, an assistant professor of geosciences at The University of Arizona in Tucson.

Now Pelletier has proposed a new explanation for the orientation, shape and speed of growth of oriented thaw lakes. The lakes’ unusual characteristics result from seasonal slumping of the banks when the permafrost thaws abruptly, he said. The lakes grow when rapid warming melts a lake’s frozen bank, and the soggy soil loses its strength and slides into the water. Such lakes are found in the permafrost zone in Alaska, northern Canada and northern Russia.

Previous explanations for the water bodies’ shape and orientation invoked wind-driven lake circulation and erosion by waves. “We knew about the thaw slumping, but we didn’t know it had to do with the shape of the lakes,” Pelletier said. His new mathematical model describing the formation of oriented lakes by thaw slumping will be published on June 30 in the Journal of Geophysical Research."

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http://uanews.org/cgi-bin/WebObjects/UANews.woa/6/wa/SRStoryDetails?ArticleID=11354

[izzie]

1. Once the top is broken the sun hits the permafrost.

It is interesting that the pipeline has cooling units in the 'rests ' that the oil pipe sits on so that the heat of the oil travel Thur the pipe will not go to the ground and melt the permafrost. Schools are also built like this in some places. Roads have a 15 foot base for the same reason and also special works have to be set up for bridges. Living in Alaska can be very costly. They are very tight on laws to build homes and building also.Also land has to be very carefully treated.

[Dogmudgeon]

2. Here's the real punch line:

Thawed ground becomes "biologically active" -- meaning billions of bacteria and small critters per cubic meter are able to live and grow where once there was only sterile ice.

They give off carbon dioxide and methane, the two primary "greenhouse gasses". Not very much individually, but spread out over the vast expanse of the Arctic, it adds up, especially in those 20- to 24- hour-long midsummer days.

If you look at the temperature charts of the arctic from now until about Thanksgiving, you will see exactly what it's doing -- most of the temperature readings have been, and will continue to be, far above historical (1900-1990) normal.

--p!