Eye in the sky points to global permafrost thaw | Polarjournal
Permafrost is the permanently frozen ground in the Arctic and high alpine regions. Only the uppermost areas thaw annually and then form marshy areas. However, these thawing processes also release greenhouse gases into the atmosphere. In recent decades, these thawing processes have become more and more pronounced. Picture: Samuel LeBlanc

The eyes in the skye, i.e. satellites, have become an indispensable part of the scientific world. With their help, global phenomena and their effects can be precisely observed. Experts then use this to investigate the causes. The permafrost can also be recorded globally with the aid of satellites and its development can be closely monitored. An international research group has achieved this for the first time with the help of a data series spanning more than 20 years.

“Average ground temperatures are rising at a rate of one degree Celsius per decade in the record”

Dr. Annett Bartsch, B.geos & Austrian Polar Research Institute

Thanks to the data produced and made available by ESA with its satellites, it has been possible to map accurately the temperatures and extent of permafrost regions in the northern hemisphere between 1997 and 2018. The researchers used temperatures from a depth of 10 metres up to the active layer of the permafrost. This is the area that thaws in summer only to freeze again as temperatures drop. The results of the research group show that temperatures are rising at different rates from region to region and are increasing the thawing of the permafrost layer. “Average ground temperatures are increasing at a rate of one degree Celsius per decade in the records,” explains Dr. Annett Bartsch of the Austrian Polar Institute APRI and head of B.geos, a remote sensing company.

The records also show, according to Dr. Bartsch, that areas such as the Russian Far East and the northwest coast of Canada near the Beaufort Sea, for example, have much higher temperature increases than other regions. These are also the places where coastal erosion and permafrost thawing are much more severe than in other areas. This is also related to each other, because the permafrost actually holds the ground together. Due to thawing, the ground loses stability and slides on the frozen part below. The result is increased erosion on coasts and in the mountains. However, this also releases increased amounts of greenhouse gases back into the atmosphere, more than is absorbed, as other studies have shown.

The time-lapse photos from 2010 show how a massive part of the coast with permafrost completely erodes away within one month. The recordings were generated at 15 minute intervals. Video: Youtube_Channel University of Colorado, Boulder

“Although ground temperatures remained close to zero degrees, on-going slow seasonal ground ice melt and a deepening of the active layer can be observed in the data.”

Professor Sebastian Westermann, University of Oslo, Department of Earth Sciences

In order to be able to create this data set, Dr. Bartsch’s team used ground temperatures measured by satellites as well as measurements of the land cover and model calculations. This is because permafrost cannot be observed directly from space. Furthermore, the data cannot be used as a direct climate warning signal. This is because the time span of 21 years is too short compared to the internationally valid three-decade minimum to use it as such a climate signal. Nevertheless, on the one hand, the trends are clearly discernible. According to co-author of the paper Professor Sebastian Westermann from the University of Oslo: “Although ground temperatures remained close to zero degrees, on-going slow seasonal ground ice melt and a deepening of the active layer can be observed in the data.” Secondly, this data set currently is the longest available for permafrost development in the Arctic. After all, the area of permafrost in the Arctic covers some 18 million square kilometres and stretches across Eurasia and North America. And only with the help of the view from above is it possible to survey such a large area in detail and yet as a whole. The data is available to the public and will help other research groups improve their understanding of the effects of thawing permafrost.

Dr Michael Wenger, PolarJournal

Link to the work:

Obu, J.; Westermann, S.; Barboux, C.; Bartsch, A.; Delaloye, R.; Grosse, G.; Heim, B.; Hugelius, G.; Irrgang, A.; Kääb, A.M.; Kroisleitner, C.; Matthes, H.; Nitze, I.; Pellet, C.; Seifert, F.M.; Strozzi, T.Wegmüller, U.; Wieczorek, M.; Wiesmann, A. (2020): ESA Permafrost Climate Change Initiative (Permafrost_cci): Permafrost active layer thickness for the Northern Hemisphere, v2.0. Centre for Environmental Data Analysis, 02 November 2020. doi:10.5285/29c4af5986ba4b9c8a3cfc33ca8d7c85.

Obu, J.; Westermann, S.; Barboux, C.; Bartsch, A.; Delaloye, R.; Grosse, G.; Heim, B.; Hugelius, G.; Irrgang, A.; Kääb, A.M.; Kroisleitner, C.; Matthes, H.; Nitze, I.; Pellet, C.; Seifert, F.M.; Strozzi, T.Wegmüller, U.; Wieczorek, M.; Wiesmann, A. (2020): ESA Permafrost Climate Change Initiative (Permafrost_cci): Permafrost ground temperature for the Northern Hemisphere, v2.0. Centre for Environmental Data Analysis, 02 November 2020. doi:10.5285/6ebcb73158b14cd5a321b7c0bc6ed393.

Obu, J.; Westermann, S.; Barboux, C.; Bartsch, A.; Delaloye, R.; Grosse, G.; Heim, B.; Hugelius, G.; Irrgang, A.; Kääb, A.M.; Kroisleitner, C.; Matthes, H.; Nitze, I.; Pellet, C.; Seifert, F.M.; Strozzi, T.Wegmüller, U.; Wieczorek, M.; Wiesmann, A. (2020): ESA Permafrost Climate Change Initiative (Permafrost_cci): Permafrost extent for the Northern Hemisphere, v2.0. Centre for Environmental Data Analysis, 02 November 2020. doi:10.5285/28e889210f884b469d7168fde4b4e54f.

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