HR: 11:05h
AN: C11E-04    [PDF]
TI: Feedbacks in Climate - Permafrost - Vegetation System: Predictive Modeling Approach.
AU: * Anisimov, O
EM: oleg@OA7661.spb.edu
AF: State Hydrological Institute, Second Line V.O., 23, St.Petersburg, 199053 Russian Federation
AU: Beloloutskaia, M
EM: marie@OA7661.spb.edu
AF: State Hydrological Institute, Second Line V.O., 23, St.Petersburg, 199053 Russian Federation
AB: Permafrost models driven by scenarios of climate change predict that reduction of the total (continuous) permafrost area in the northern hemisphere by 2030, 2050, and 2080 is likely to be 10%-18% (15%-25%); 15%-30% (20%-40%), and 20%-35% (25%-50%), respectively. Predicted changes of the seasonal thaw depth in the following three decades are relatively small, typically within 10%-15%. By the middle of the century thaw depth may increase on average by 15%-25%, and by 50% and more in the northernmost locations. By 2080 layer of seasonal thawing will become markedly thicker (by 30%-50% and more) all over the permafrost area. Vegetation above permafrost plays important role in regulating ground temperature and depth of seasonal thawing. In the warm period organic layer of peat, mosses, and lichens has low thermal conductivity and protects permafrost from thawing. Results from coupled climate - permafrost - vegetation model suggest that 5cm, 10cm, 15cm, and 20cm thick organic layer reduces seasonal thaw depth by 10%, 25%, 40%, and 60%, respectively, compared to bare ground. Enhanced growth of non-vascular plants under warmer climatic conditions may thus mitigate the effects of climatic warming on permafrost. Controlled experiments involving continuous localized warming at selected sites in the northern Europe and in Alaska indicate a multiyear tendency towards the replacement of mosses and lichens by vascular plants. In the long term climate-induced changes of vegetation may thus cause enhances warming and deeper seasonal thawing of the frozen ground ultimately leading to degradation of permafrost. Acknowledgement. This work is supported by the National Science Foundation of the Netherlands, grant \# 047.011.2001.003.
DE: 1630 Impact phenomena
DE: 1823 Frozen ground
SC: Cryosphere [C]
MN: 2003 Fall Meeting