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TitreThermal state of permafrost - an overview and status of activities in the polar northern hemisphere
AuteurRomanovsky, V E; Marchenko, S S; Christiansen, H H; Smith, S L
SourceThermal state of frozen ground in a changing climate during the IPY, Abstracts from the Third European Conference on Permafrost; par Mertes, J R (éd.); Christiansen, H H (éd.); Etzelmüller, B (éd.); 2010 p. 11
Année2010
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100071
Réunion3rd European Conference on Permafrost; Longyearbyen Svalbard; NO; juin 14-18, 2010
Documentlivre
Lang.anglais
Mediapapier
ProvinceTerritoires du Nord-Ouest; Nunavut; Yukon
SNRC25; 26; 27; 35; 36; 37; 38; 39; 45; 46; 47; 48; 49; 55; 56; 57; 58; 59; 65; 66; 67; 68; 69; 75; 76; 77; 78; 79; 85; 86; 87; 88; 89; 95; 96; 97; 98; 99; 105; 116; 107; 115; 117; 120; 340; 560
Lat/Long OENS-180.0000 180.0000 90.0000 60.0000
Sujetspergélisol; congélation du sol; glace fossile; températures au sol; climat arctique; géologie des dépôts meubles/géomorphologie; géologie de l'environnement
ProgrammeLes sciences de la Terre à l'appui de la caractérisation, à l'échelle nationale, des impacts des changements climatiques sur la masse continentale canadienne, Géosciences de changements climatiques
Résumé(disponible en anglais seulement)
1 INTRODUCTION
Permafrost is an important part of the cryosphere and is a key cryospheric indicator of climate change. During the International Polar Year (IPY) 2007-2009, a global snapshot of the permafrost thermal state was obtained through a coordinated field campaign. This paper focuses on the information on the permafrost thermal state obtained during the IPY in all parts of the polar Northern Hemisphere through several regional and national research projects. The campaign was the key component of the IPY research project, 'Permafrost Observatory Network: A Contribution to the Thermal State of Permafrost (TSP)'.
2 METHODS
The snapshot was obtained by continuing measurements at existing permafrost observatory sites, by re-occupying older sites where permafrost temperatures were measured in the past but were interrupted lately, and by drilling new boreholes and establishing new observatory sites with long-term ground temperature monitoring. Different equipment and techniques were used for borehole temperature measurements in different countries and at different time. The earliest systematic measurements in the European North of Russia go back to the 1930s. During that initial period, temperatures in the boreholes were measured using mercury thermometers with a scale factor from 0.05 to 0.1°C. Starting from the 1950s and especially in the 1960s, semi-conducting temperature sensors (thermistors) became more common in permafrost geothermal studies. Since then, most of the boreholes at the permafrost research stations were equipped with permanently or temporary installed thermistor strings and temperatures were measured periodically. During the last 20 years, digital data loggers have been used more and more commonly for ground temperature automatic data acquisition and storage.
The diversity of past measuring techniques could lead to uncertainty when comparing data obtained using these different sensors. Special field experiments were performed during the 2007 and 2008 field seasons to address this concern. These experiments assure the comparability of all measurement techniques at an overall accuracy of 0.1°C.
Even the longest records of the permafrost temperature dynamics are still very time-limited. To extend the knowledge on changes in the permafrost thermal state into the past and to project possible future changes, various numerical permafrost models with different levels of complexity are usually implemented. In this presentation we will give a short review of existing models and discuss the results of some of these modeling efforts.
3 RESULTS
Looking back into the last three years of international permafrost research activities, we can definitely conclude that IPY-TSP was a success. The major part of the success was due to significantly increased international scientific cooperation which led to development and operation of the TSP project. Data collected through the TSP project have enabled, for the first time, an overall Northern Hemisphere synthesis of the current permafrost thermal state, which will provide a baseline against which future change may be measured. The addition of new monitoring sites in areas that were previously under-represented has resulted in new information on permafrost thermal state for regions where little or no recent information was available.
Most of the permafrost observatories in the Northern Hemisphere show substantial warming of permafrost during the last 20 to 30 years. The magnitude of warming varied with location, but was typically from 0.5 to 2°C at the depth of zero annual amplitude. The main exceptions are those sites with ice-rich fine-grained sediments where ground temperatures are within a few tenths of a degree below 0°C where ground temperature profiles are isothermal, indicating that phase change is occurring within the permafrost.
Permafrost is already thawing in specific landscape settings within the southern part of the permafrost domain. Formation of new closed taliks and an increase in depth of pre-existing taliks has been observed in this area during the last 20 to 30 years.
GEOSCAN ID285484