Simulated high-latitude soil thermal dynamics during the past 4 decades

• Published in: The Cryosphere
• Main Authors: Peng, S., Ciais, Philippe, Krinner, Gerhard, Wang, Tao, Gouttevin, Isabelle, McGuire, A.D, Lawrence, D., Burke, E., Chen, X., Decharme, B., Koven, C., Macdougall, A, Rinke, A., Saito, K., Zhang, W., Alkama, R., Bohn, T.J, Delire, C., Hajima, T, Ji, D., Lettenmaier, D. P., Miller, P.A, Moore, J.C., Smith, B., Sueyoshi, T
• Other Authors: Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 ), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), University of Alaska Fairbanks (UAF), National Center for Atmospheric Research Boulder (NCAR), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office Exeter, Department of Civil and Environmental Engineering, University of Washington, University of Washington Seattle, Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Lawrence Berkeley National Laboratory Berkeley (LBNL), University of Victoria Canada (UVIC), College of Global Change and Earth System Science (GCESS), Beijing Normal University (BNU), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Research Institute for Global Change (RIGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Department of Physical Geography and Ecosystem Science Lund, Lund University Lund, ASU School of Earth and Space Exploration (SESE), Arizona State University Tempe (ASU), National Institute of Polar Research Tokyo (NiPR)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: PERMAFROST; CLIMATE FORCING; HIGH LATITUDES CLIMATE; SOIL TEMPERATURE; CLIMATE MODEL; LAND SURFACE MODEL; [SDE]Environmental Sciences; Active layer thickness; permafrost; The Cryosphere
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01388162; https://hal-insu.archives-ouvertes.fr/insu-01388162/document; https://hal-insu.archives-ouvertes.fr/insu-01388162/file/CRYOSPHERE%20-%20Simulated%20high-latitude%20soil%20thermal%20dynamics%20during%20the%20past%204%20decades.pdf; https://doi.org/10.5194/tc-10-179-2016

International audience Soil temperature (Ts) change is a key indicator of the dynamics of permafrost. On seasonal and interannual timescales, the variability of Ts determines the active-layer depth, which regulates hydrological soil properties and biogeochemical processes. On the multi-decadal scale, increasing Ts not only drives permafrost thaw/retreat but can also trigger and accelerate the decomposition of soil organic carbon. The magnitude of permafrost carbon feedbacks is thus closely linked to the rate of change of soil thermal regimes. In this study, we used nine process-based ecosystem models with permafrost processes, all forced by different observation-based climate forcing during the period 1960–2000, to characterize the warming rate of Ts in permafrost regions. There is a large spread of Ts trends at 20 cm depth across the models, with trend values ranging from 0.010 ± 0.003 to 0.031 ± 0.005 °C yr−1. Most models show smaller increase in Ts with increasing depth. Air temperature (Tsub>a) and longwave downward radiation (LWDR) are the main drivers of Ts trends, but their relative contributions differ amongst the models. Different trends of LWDR used in the forcing of models can explain 61 % of their differences in Ts trends, while trends of Ta only explain 5 % of the differences in Ts trends. Uncertain climate forcing contributes a larger uncertainty in Ts trends (0.021 ± 0.008 °C yr−1, mean ± standard deviation) than the uncertainty of model structure (0.012 ± 0.001 °C yr−1), diagnosed from the range of response between different models, normalized to the same forcing. In addition, the loss rate of near-surface permafrost area, defined as total area where the maximum seasonal active-layer thickness (ALT) is less than 3 m loss rate, is found to be significantly correlated with the magnitude of the trends of Ts at 1 m depth across the models (R = −0.85, P = 0.003), but not with the initial total near-surface permafrost area (R = −0.30, P = 0.438). The sensitivity of the total boreal near-surface ...