A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback

• Published in: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
• Main Authors: Koven, C.D, Schuur, E.A.G., Schädel, C, Bohn, T. J, Burke, E.J., Chen, G., Chen, X, Ciais, Philippe, Grosse, G, Harden, J.W, Hayes, D.J, Hugelius, G, Jafarov, E.E, Krinner, G, Kuhry, P, Lawrence, D.M., MacDougall, A.H, Marchenko, S.S, McGuire, A.D, Natali, S.M, Nicolsky, D. J., Olefeldt, D, Peng, S, Romanovsky, V. E., Schaefer, K.M, Strauss, J, Treat, C.C, Turetsky, M.
• Other Authors: Lawrence Berkeley National Laboratory Berkeley (LBNL), Northern Arizona University Flagstaff, University of Washington Seattle, ASU School of Earth and Space Exploration (SESE), Arizona State University Tempe (ASU), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office Exeter, Oak Ridge National Laboratory Oak Ridge (ORNL), UT-Battelle, LLC, 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), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), United States Geological Survey Reston (USGS), Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, National Snow and Ice Data Center (NSIDC), University of Colorado Boulder, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-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 Joseph Fourier - Grenoble 1 (UJF)-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), National Center for Atmospheric Research Boulder (NCAR), School of Earth and Ocean Sciences, University of Victoria, University of Victoria Canada (UVIC), University of Alaska Fairbanks (UAF), Woods Hole Oceanographic Institution (WHOI), Geophysical Institute Fairbanks, University of Alberta, Department of Biology, University of Western Ontario, University of Western Ontario (UWO)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: methane; climate change; carbon–climate feedbacks; permafrost; [SDE]Environmental Sciences
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01326116; https://hal-insu.archives-ouvertes.fr/insu-01326116/document; https://hal-insu.archives-ouvertes.fr/insu-01326116/file/rsta.2014.0423.pdf; https://doi.org/10.1098/rsta.2014.0423

International audience We present an approach to estimate the feedback from large-scale thawing of permafrost soils using a simplified, data-constrained model that combines three elements: soil carbon (C) maps and profiles to identify the distribution and type of C in permafrost soils; incubation experiments to quantify the rates of C lost after thaw; and models of soil thermal dynamics in response to climate warming. We call the approach the Permafrost Carbon Network Incubation–Panarctic Thermal scaling approach (PInc-PanTher). The approach assumes that C stocks do not decompose at all when frozen, but once thawed follow set decomposition trajectories as a function of soil temperature. The trajectories are determined according to a three-pool decomposition model fitted to incubation data using parameters specific to soil horizon types. We calculate litterfall C inputs required to maintain steady-state C balance for the current climate, and hold those inputs constant. Soil temperatures are taken from the soil thermal modules of ecosystem model simulations forced by a common set of future climate change anomalies under two warming scenarios over the period 2010 to 2100. Under a medium warming scenario (RCP4.5), the approach projects permafrost soil C losses of 12.2–33.4 Pg C; under a high warming scenario (RCP8.5), the approach projects C losses of 27.9–112.6 Pg C. Projected C losses are roughly linearly proportional to global temperature changes across the two scenarios. These results indicate a global sensitivity of frozen soil C to climate change (γ sensitivity) of −14 to −19 Pg C • C −1 on a 100 year time scale. For CH 4 emissions, our approach assumes a fixed saturated area and that increases in CH 4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH 4 emission increases of 7% and 35% for the RCP4.5 and RCP8.5 scenarios, respectively, which add an additional greenhouse gas forcing of approximately 10–18%. The simplified approach presented here neglects many important ...