The Vulnerability of Permafrost from 1960 to 2300 Based on Simulations of the Process-Based Model GIPL2 Across the Permafrost Region in the Northern Hemisphere: Implications for Soil Carbon Vulnerability

Thursday, 18 December 2014: 1:55 PM
Sergey S Marchenko1, Dmitry Nicolsky1, Vladimir E Romanovsky1 and Anthony David McGuire2, (1)University of Alaska Fairbanks, Fairbanks, AK, United States, (2)University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK, United States
Recent observations indicate a warming of permafrost in many northern regions with a resulting degradation of ice-rich and carbon-rich permafrost. In the last 30-40 years, warming in permafrost temperatures observed in Northern Eurasia, Canada, and Alaska has resulted in the thawing of permafrost in natural, undisturbed conditions in areas close to the southern boundary of the permafrost zone. The main aim of this study is to evaluate the vulnerability of permafrost under climate warming across the Permafrost Region of the Northern Hemisphere. We applied the process-based permafrost dynamics model GIPL2 (Geophysical Institute Permafrost Lab), using a historical climate forcing CRU3.1 data set for retrospective (1960-2009) and CCSM4 RCP4.5 and RCP8.5 (2009-2300) for analysis of permafrost dynamics in the future. We estimated dynamics of the area and volume of seasonally thawed soils within the three upper meters across the entire Permafrost Domain. During the last four decades of the 20th century, the simulated total area and the volume of thawed soils with Active Layer Thickness (ALT) shallower than 3 m has been varying between 11 and 13 million km2, and between 17.3 to 19.4 thousand km3 respectively. Our projections according to the CCSM4 RCP4.5 climate scenario indicate that the maximum unfrozen volume of soil within three upper meters would change between 12.8 and 20.8 thousand km3 during 2009-2300. Despite the slower rate of soil warming in peatland areas and a slower degradation of permafrost under peat soils, a considerable volume of peat (approximately 20% of the total volume of peat in the Northern Hemisphere) could be thawed by the end of the current century and 35% by 2300. The potential release of carbon and the net effect of this thawing will depend on the balance between increased productivity and respiration, and will also depend on soil moisture dynamics.