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

Details

• Journal Title:
  Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
• Personal Author:
  Koven, C. D. ; Schuur, E. A. G. ; Schädel, C. ; Bohn, T. J. ; Burke, E. J. ; Chen, G. ; Chen, X. ; Ciais, P. ; 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.
• NOAA Program & Office:
  NESDIS (National Environmental Satellite, Data, and Information Service) ; NCEI (National Centers for Environmental Information)
• Description:
  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 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.
• Keywords:
  General Engineering General Mathematics General Physics And Astronomy General Physics And Astronomy General Physics And Astronomy
• Source:
  Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 373(2054), 20140423
• DOI:
  https://doi.org/10.1098/rsta.2014.0423
• ISSN:
  1364-503X ; 1471-2962
• Format:
  PDF
• Publisher:
  The Royal Society
• Document Type:
  Journal Article
• License:
  https://creativecommons.org/licenses/by/4.0/
• Rights Information:
  CC BY
• Compliance:
  Library
• Main Document Checksum:
  urn:sha256:a32f48e3e3e47e3cf654f418beb6d233b078ddbda8921dec8f601b2561391ab8
• Download URL:
  https://repository.library.noaa.gov/view/noaa/53699/noaa_53699_DS1.pdf
• File Type:
  [PDF - 1002.34 KB ]