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kassy

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Permafrost general science thread
« on: January 16, 2019, 02:42:56 PM »
I decided to make a new thread for general science on permafrost because the other threads are about either methane or snow cover or really specific issues.


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The pace at which the world's permafrost soils are warming

As the new global comparative study conducted by the international permafrost network GTN-P shows, in all regions with permafrost soils the temperature of the frozen ground at a depth of more than 10 metres rose by an average of 0.3 degrees Celsius between 2007 and 2016 - in the Arctic and Antarctic, as well as the high mountain ranges of Europe and Central Asia. The effect was most pronounced in Siberia, where the temperature of the frozen soil rose by nearly 1 degree Celsius. The pioneering study has just been released in the online journal Nature Communications.

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The complete dataset encompasses 154 boreholes, 123 of which allow conclusions to be drawn for an entire decade, while the remainder can be used to refine calculations on annual deviation. The results show that, in the ten years from 2007 to 2016, the temperature of the permafrost soil rose at 71 of the 123 measuring sites; in five of the boreholes, the permafrost was already thawing. In contrast, the soil temperature sank at 12 boreholes, e.g. at individual sites in eastern Canada, southern Eurasia and on the Antarctic Peninsula; at 40 boreholes, the temperature remained virtually unchanged.

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The researchers observed the most dramatic warming in the Arctic: "There, in regions with more than 90 percent permafrost content, the soil temperature rose by an average of 0.30 degrees Celsius within ten years," reports first author Dr Boris Biskaborn, a member of the research group Polar Terrestrial Environmental Systems at the Potsdam facilities of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research. In northeast and northwest Siberia, the temperature increase at some boreholes was 0.90 degrees Celsius or even higher. For the sake of comparison: the air temperature in the respective regions rose by an average of 0.61 degrees Celsius in the same period.

Farther south, in Arctic regions with less than 90 percent permafrost, the frozen ground only warmed by 0.2 degrees Celsius on average. "In these regions there is more and more snowfall, which insulates the permafrost in two ways, following the igloo principle: in winter the snow protects the soil from extreme cold, which on average produces a warming effect. In spring it reflects the sunlight, and prevents the soil from being exposed to too much warmth, at least until the snow has completely melted away," Biskaborn explains.

Significant warming can also be seen in the permafrost regions of the high mountain ranges, and in the Antarctic. The temperature of the permanently frozen soils in the Alps, in the Himalayas and in the mountain ranges of the Nordic countries rose by an average of 0.19 degrees Celsius. In the shallow boreholes in the Antarctic, the researchers measured a rise of 0.37 degrees.

for full details:
https://www.eurekalert.org/pub_releases/2019-01/awih-tpa011519.php

Bernard

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Re: Permafrost general science thread
« Reply #1 on: January 16, 2019, 11:35:54 PM »
I just read the quoted article at phys.org
https://phys.org/news/2019-01-pace-world-permafrost-soils.html
One thing I was wondering is if similar studies are conducted in other places than permafrost. We have measures of sea water temperatures at different depths, but the global warming should also be measured in mean temperatures of underground, at depths where the temperature is stable year-round (about 10-20m if what I read is correct), whether this underground is frozen or not.
This is a bit off-topic, please point me to an existing thread if any.

Meanwhile, I created one such topic
https://forum.arctic-sea-ice.net/index.php/topic,2548.0.html
« Last Edit: January 17, 2019, 12:21:38 AM by Bernard »