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

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 approachmore » 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 CH4 emissions, our approach assumes a fixed saturated area and that increases in CH4 emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH4 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%. In conclusion, the simplified approach presented here neglects many important processes that may amplify or mitigate C release from permafrost soils, but serves as a data-constrained estimate on the forced, large-scale permafrost C response to warming.« less
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [5] ;  [10] ;  [11] ;  [12] ;  [10] ;  [13] ;  [14] ;  [15] ;  [15] ;  [16] more »;  [15] ;  [17] ;  [18] ;  [15] ;  [11] ;  [8] ;  [9] ;  [19] « less
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Northern Arizona Univ., Flagstaff, AZ (United States)
  3. Univ. of Washington, Seattle, WA (United States); Arizona State Univ., Tempe, AZ (United States)
  4. Met Office Hadley Centre, Exeter (United Kingdom)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Univ. of Washington, Seattle, WA (United States)
  7. Lab des Sciences du Climat et de l'Environnement (LSCE CEA-CNRS-UVSQ) Gif-sur-Yvette (France)
  8. Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam (Germany)
  9. United States Geological Survey, Menlo Park, CA (United States)
  10. Stockholm Univ., Stockholm (Sweden)
  11. Univ. of Colorado, Boulder, CO (United States)
  12. Lab de Glaciologie et Geophysique de l'Environnement, CNRS and Univ. Grenoble Alpes, Grenoble (France)
  13. National Center for Atmospheric Research, Boulder, CO (United States)
  14. Univ. of Victoria, Victoria, BC (Canada)
  15. Univ. of Alaska, Fairbanks, AK (United States)
  16. Woods Hole Research Center, Falmouth, MA (United States)
  17. Univ. of Alberta, Edmonton, AB (Canada)
  18. Lab des Sciences du Climat et de l'Environnement (LSCE CEA-CNRS-UVSQ) Gif-sur-Yvette (France); Lab de Glaciologie et Geophysique de l'Environnement, CNRS and Univ. Grenoble Alpes, Grenoble (France)
  19. Univ. of Ontario, Guelph, ON (Canada)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-05CH11231; FC03-97ER62402/A010; ARC-1048997; ARC-1048987
Accepted Manuscript
Journal Name:
Philosophical Transactions. Mathematical, Physical & Engineering Sciences
Additional Journal Information:
Journal Volume: 373; Journal Issue: 2054; Journal ID: ISSN 1364-503X
Royal Society
Research Org:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES permafrost; climate change; carbon–climate feedbacks; methane