E.A.G. Schuur
C. Schädel
T. J. Bohn
E. J. Burke
G. Chen
X. Chen
P. Ciais
G. Grosse
J.W. Harden
D.J. Hayes
G. Hugelius
Elchin E. Jafarov
G. Krinner
P. Kuhry
D.M. Lawrence
A. H. MacDougall
Sergey S. Marchenko
A. David McGuire
Susan M. Natali
D.J. Nicolsky
David Olefeldt
S. Peng
V.E. Romanovsky
Kevin M. Schaefer
J. Strauss
Claire C. Treat
M. Turetsky
C.D. Koven
2015
<p><span>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 (</span><i>γ </i><span>sensitivity) of −14 to −19 Pg C °C</span><sup><span>−1</span></sup><span> on a 100 year time scale. For CH</span><sub><span>4</span></sub><span> emissions, our approach assumes a fixed saturated area and that increases in CH</span><sub><span>4</span></sub><span> emissions are related to increased heterotrophic respiration in anoxic soil, yielding CH</span><sub><span>4</span></sub><span> 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.</span></p>
application/pdf
10.1098/rsta.2014.0423
en
The Royal Society
A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback
article