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

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 scenariomore » (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 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%. Finally, 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
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [5] ;  [10] ;  [11] ;  [12] ;  [10] ;  [13] ;  [14] ;  [15] ;  [16] ;  [17] more »;  [15] ;  [18] ;  [19] ;  [15] ;  [11] ;  [8] ;  [9] ;  [20] « less
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division
  2. Northern Arizona Univ., Flagstaff, AZ (United States). Center for Ecosystem Science and Society
  3. Univ. of Washington, Seattle, WA (United States). Dept. of Civil and Environmental Engineering; Arizona State Univ., Tempe, AZ (United States). School of Earth and Space Exploration
  4. Met Office Hadley Centre, Exeter (United Kingdom)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
  6. Univ. of Washington, Seattle, WA (United States). Dept. of Civil and Environmental Engineering
  7. Lab. des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette (France)
  8. Alfred Wegener Inst., Helmholtz Centre for Polar and Marine Research, Potsdam (Germany). Periglacial Research Unit
  9. U.S. Geological Survey, Menlo Park, CA (United States)
  10. Stockholm Univ. (Sweden). Dept. of Physical Geography. Bolin Centre of Climate Research
  11. Univ. of Colorado, Boulder, CO (United States). National Snow and Ice Data Center
  12. CNRS and Univ. Grenoble Alpes, Grenoble (France). Lab. de Glaciologie et Geophysique de l'Environnement
  13. National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Division
  14. Univ. of Victoria, BC (Canada). School of Earth and Ocean Sciences
  15. Univ. of Alaska, Fairbanks, AK (United States). Geophysical Inst. Permafrost Lab.
  16. Univ. of Alaska, Fairbanks, AK (United States). US Geological Survey. Alaska Cooperative Fish and Wildlife Research Unit
  17. Woods Hole Research Center, Falmouth, MA (United States)
  18. Univ. of Alberta, Edmonton, AB (Canada). Dept. of Renewable Resources
  19. Lab. des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette (France); CNRS and Univ. Grenoble Alpes, Grenoble (France). Lab. de Glaciologie et Geophysique de l'Environnement
  20. Univ. of Ontario, Guelph, ON (Canada). Dept. of Integrative Biology
Publication Date:
Grant/Contract Number:
AC02-05CH11231; SC0006982; FC03-97ER62402/A010
Type:
Accepted Manuscript
Journal Name:
Philosophical Transactions of the Royal Society. A, Mathematical, Physical and Engineering Sciences
Additional Journal Information:
Journal Volume: 373; Journal Issue: 2054; Journal ID: ISSN 1364-503X
Publisher:
The Royal Society Publishing
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Contributing Orgs:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 29 ENERGY PLANNING, POLICY, AND ECONOMY permafrost; climate change; carbon-climate feedbacks; methane
OSTI Identifier:
1265528
Alternate Identifier(s):
OSTI ID: 1265528