Earth’s Cryosphere, 2010, Vol. XIV, No. 3, p. 37-42

MODELLING OF SUBSIDENCE OF PERENNIALLY FROZEN SOIL DUE TO THAW FOR THE NORTHERN HEMISPHERE DURING THE 21ST CENTURY

M.M. Arzhanov, P.F. Demchenko, A.V. Eliseev, I.I. Mokhov

Obukhov Institute of Atmospheric Physics, RAS, 119017, Moscow, Pyzhevsky per., 3, Russia, arzhanov@ifaran.ru

A technique for assessing the subsidence of perennially frozen soil due to thaw is based on simulations with a model for thermal and hydrological processes in soil. Quantitative estimations of mechanic changes due to subsurface permafrost degradation are obtained. If atmospheric forcing is prescribed based on simulations with the the ECHAM5/MPI-OM general circulation model under the scenario SRES A1B, the modelled permafrost extent will decrease from 16.6 mln sq km by 7.9 mln sq km by the end of the 21st century. Active layer thickness may increase by 0.2–0.6 m. Most marked permafrost degradation is simulated for the last decades of the 21st century. However, subsurface permafrost can turn to relic form even in decade 2020–2030 in the regions near the contemporary permafrost southern boundary in the Northern Hemisphere. Typical values of vertical shifts of soil layers amount to several tens of centimetres and reach up to 0.9 m locally.

Key words: Thaw subsidence, permafrost, simulation of heat and moisture transfer.

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