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Titre4. Changing Permafrost and its Impacts
AuteurRomanovsky, V E; Isaksen, K; Drozdov, D; Anisimov, O; Instanes, A; Leibman, M; McGuire, A D; Smith, S L; Walker, D
SourceSnow, water, ice and permafrost in the arctic (SWIPA) 2017 : Scientific report; 2017.
Année2017
Séries alt.Secteur des sciences de la Terre, Contribution externe 20150459
ÉditeurArctic Monitoring and Assessment Program
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceNunavut; Territoires du Nord-Ouest; Yukon
Lat/Long OENS -18.0000 0.0000 90.0000 66.0000
Sujetsétablissement de modèles; climat arctique; effets climatiques; climat; pergélisol; temperature; températures au sol; végétation; érosion côtière; géologie des dépôts meubles/géomorphologie
Illustrationsgraphs; tables; location maps; photographs
ProgrammeSurveillance des variables climatiques, Géosciences de changements climatiques
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
Key findings Since IPY in 2007-08, new record high ground temperatures have been observed at many permafrost observatories across the Arctic. The greatest temperature increase, more than 0.5°C, occurred in the colder permafrost of the Arctic and high Arctic. In warmer permafrost such as that in the southern and central Mackenzie Valley, in the Alaskan Interior, or in the discontinuous permafrost zone in Siberia and the Nordic region the temperature increase has been much smaller or not detectable. At some few locations (e.g. in the Alaskan Interior) permafrost temperature has even slightly decreased (typically by 0.1°C). Most of the regions where long-term active layer thickness (ALT) observations are available show an increase in ALT during the last 5 years. In northern Alaska, complete freeze-up of the active layer in the mid-1980s typically occurred in the first half of October but has shifted to the middle December in the first half of the 2010s; the average date of freeze-up increased by almost two months. At some locations (e.g. in the European North of Russia) permafrost degradation has been observed. Since the SWIPA 2011 report, there have been substantial efforts to evaluate large-scale models of permafrost dynamics across the circumpolar north, and we now have a better understanding of the range of uncertainty in projections associated with both the models themselves and with the future projections of climate change. Progress has also been made in modeling the effects of vegetation change on permafrost dynamics in response to changing climate and modelling the dynamics of sub-sea permafrost beneath the continental shelf of the Arctic Ocean. A significant increase in areas of water-filled polygonal troughs was reported in Northern Alaska and linked to climatic changes. However, no unified trends in thermokarst development associated with global warming have been observed across the Arctic.. Changes in thermokarst lake development are related to both regional and local environmental and climatic factors, including the moisture balance. Incorporation of thermokarst and thermo-erosion processes in complex land surface models will be important to fully capture future responses of permafrost dynamics in a warming Arctic and related climatic feedbacks. Geographic assessments of changes in bearing capacity for some of the largest settlements on permafrost in the Russian Arctic indicate significant reduction between 1970 and 2050, with the largest decrease in bearing capacity (75-95% relative to 1970) predicted for the southern fringes of the permafrost zone. The Prudhoe Bay oilfield (PBO) in Alaska and Bovanenkovo gas field (BGF) on the Yamal Peninsula of Russia have experienced recent changes in permafrost conditions due to a series of warm summers that triggered major increases in thermokarst in the PBO and themocirques near the BGF.
Résumé(Résumé en langage clair et simple, non publié)
Le présent rapport constitue une mise à jour du chapitre sur le pergélisol du rapport SWIPA (Snow, Water, Ice, and Permafrost in the Arctic ou neige, eau, glace et pergélisol dans l'Arctique), publié en 2012 par le Programme de surveillance et d'évaluation de l'Arctique. Le rapport documente les changements dans la température du pergélisol et l'épaisseur de la couche active qui se sont produits au cours des cinq dernières années et les placent dans le contexte des registres à long terme. En général, le pergélisol continue à se réchauffer et les couches actives sont devenues plus épaisses dans tout le Nord circumpolaire. De nouveaux renseignements sur les projections des conditions futures du pergélisol, les impacts du réchauffement du pergélisol sur l'environnement, tant naturel qu'aménagé, et les mesures pour faire face aux défis qui découlent des changements climatiques sont également présentés. Le rapport informe, en contribuant à la base scientifique, le projet de mesures d'adaptation pour un Arctique en évolution (Adaptation Actions for a Changing Arctic) du Conseil de l'Arctique et son évaluation de la manière dont les adaptations aux conditions changeantes du pergélisol peuvent se faire et la conception de stratégies d'adaptation aux changements climatiques.
GEOSCAN ID297748