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Author Topic: Permafrost Melt, Perhaps Not As Bad As We Feared...  (Read 3017 times)

Bob Wallace

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Permafrost Melt, Perhaps Not As Bad As We Feared...
« on: May 23, 2013, 05:28:52 AM »
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Researchers have uncovered a mechanism in the Alaskan tundra that doesn't seem to follow the climate change script for soil carbon.

For years, scientists have shown that rising temperatures stimulate microbes that decay plant matter, releasing carbon more quickly into the atmosphere. But when Seeta Sistla, a doctoral student at the University of California, Santa Barbara, came to collect data for a 20-year-old experiment at the U.S. Arctic Long-Term Ecological Research site in northern Alaska, the soil carbon levels at the site were curiously stable.

While climate change is warming the soil and spurring microorganisms to decompose leaves -- which releases carbon into the air -- the growth of more shrubbery in the tundra is soaking up that carbon and redistributing it back into the ground.

....

The researchers collected samples dating back to 1989 from greenhouses at the Arctic Long-Term Ecological Research site, the longest-running whole system tundra warming experiment.

Overall, there was no change in total soil carbon over 20 years. While the surface layer lost some of its carbon, there was a significant increase in the mineral soils more than 2 feet below the surface. These soils typically don't hold a lot of carbon, but the researchers believe warming has encouraged soil nematodes and mites, which help decompose leaves and other plant matter, to make their way to the deeper soils.

"Deeper soil food webs are looking like surface soil food webs," Schimel said.

This redistribution of soil carbon storage raises questions of whether the balance provided by larger plants will stand in the long term or whether the more active microbes detected in the deeper soils will eventually offset the increased carbon in those deeper soils.

http://www.scientificamerican.com/article.cfm?id=thawing-tundra-may-produce-less-co2

(I posted this in the Science forum and then remembered there was a Permafrost forum.  Feel free to kill one if desired.)

sidd

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Re: Permafrost Melt, Perhaps Not As Bad As We Feared...
« Reply #1 on: May 23, 2013, 05:50:24 AM »
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12129.html

is  the paper, dealing with moist acidic tussock tundra ecosystem. in addition please see Vonk et al.(2013) on biolability of dissolved inorganic carbon from yedoma in the Kolyma peninsula

http://www.thepolarisproject.org/wp-content/uploads/2011/06/Vonk_2013.pdf

and for a view from another end of earth,  the Amazon on mobilization of forest sequestered carbon

DOI: 10.1038/NGEO1817

sidd

Apocalypse4Real

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Re: Permafrost Melt, Perhaps Not As Bad As We Feared...
« Reply #2 on: July 21, 2013, 07:00:04 PM »
However, ongoing research shows that permafrost is warming, in some cases as much as .5 C at 15 meters below the surface in the Hudson Bay lowlands.

See: Warmer temps threaten railway
Churchill shipping runs over peatland

By: Bill Redekop, Friday, Jul. 12, 2013 at 8:25 AM

http://www.brandonsun.com/breaking-news/warmer-temps-threaten-railway-215197711.html?thx=y

AbruptSLR

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Re: Permafrost Melt, Perhaps Not As Bad As We Feared...
« Reply #3 on: July 22, 2013, 04:49:47 AM »
Anyone who thinks that an increase in the growth of shrubs in the tundra is a net long-term negative feedback is not considering either: (a) the decreased albedo from the shrubs and (b) the increased risk of wildfires in the tundra (which would not only release the temporarily sequestered carbon, but would also distribute black carbon around the Arctic.
β€œIt is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson