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. Univ. of Washington, Seattle, WA . Dept. of Civil and Environmental Engineering; Arizona State Univ., Tempe, AZ . School of Earth and Space Exploration, Burke, E. J. Met Office Hadley Centre, Exeter, Chen, G. Oak Ridge National Lab. , Oak Ridge, TN . Environmental Sciences Division, Chen, X. Univ. of Washington, Seattle, WA . Dept. of Civil and Environmental Engineering, Ciais, P. Lab. des Sciences du Climat et de l'Environnement , Gif-sur-Yvette, Grosse, G. Alfred Wegener Inst., Helmholtz Centre for Polar and Marine Research, Potsdam . Periglacial Research Unit, Harden, J. W. U.S. Geological Survey, Menlo Park, CA, Hayes, D. J. Oak Ridge National Lab. , Oak Ridge, TN . Environmental Sciences Division, Hugelius, G. Stockholm Univ. . Dept. of Physical Geography. Bolin Centre of Climate Research, Jafarov, E. E. Univ. of Colorado, Boulder, CO . National Snow and Ice Data Center, Krinner, G. CNRS and Univ. Grenoble Alpes, Grenoble . Lab. de Glaciologie et Geophysique de l'Environnement, Kuhry, P. Stockholm Univ. . Dept. of Physical Geography. Bolin Centre of Climate Research, Lawrence, D. M. National Center for Atmospheric Research, Boulder, CO . Climate and Global Dynamics Division, MacDougall, A. H. Univ. of Victoria, BC . School of Earth and Ocean Sciences, Marchenko, S. S. Univ. of Alaska, Fairbanks, AK . Geophysical Inst. Permafrost Lab., McGuire, A. D. Univ. of Alaska, Fairbanks, AK . US Geological Survey. Alaska Cooperative Fish and Wildlife Research Unit, Natali, S. M. Woods Hole Research Center, Falmouth, MA, Nicolsky, D. J. Univ. of Alaska, Fairbanks, AK . Geophysical Inst. Permafrost Lab., Olefeldt, D. Univ. of Alberta, Edmonton, AB . Dept. of Renewable Resources, Peng, S. Lab. des Sciences du Climat et de l'Environnement , Gif-sur-Yvette, CNRS and Univ. Grenoble Alpes, Grenoble . Lab. de Glaciologie et Geophysique de l'Environnement, Romanovsky, V. E. Univ. of Alaska, Fairbanks, AK . Geophysical Inst. Permafrost Lab., Schaefer, K. M. Univ. of Colorado, Boulder, CO . National Snow and Ice Data Center, Strauss, J. Alfred Wegener Inst., Helmholtz Centre for Polar and Marine Research, Potsdam . Periglacial Research Unit, Treat, C. C. U.S. Geological Survey, Menlo Park, CA, Turetsky, M. Univ. of Ontario, Guelph, ON . Dept. of Integrative Biology
• Language: unknown
• Published: 2023
• Subjects: 54 ENVIRONMENTAL SCIENCES; 29 ENERGY PLANNING; POLICY; AND ECONOMY; permafrost
• Online Access: http://www.osti.gov/servlets/purl/1265528; https://www.osti.gov/biblio/1265528; https://doi.org/10.1098/rsta.2014.0423

In this paper, 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%. Finally, the simplified approach presented here neglects many important ...