Permafrost degradation and climate-related thermokarst dynamics in populated Central Yakutia, Eastern Siberia

摘要

The monitoring of permafrost landscapes is a cornerstone for the quantifications of future environmental changes and their impacts on periglacial areas. Thawing permafrost has been caused massive landscape changes, enhanced release of organic carbon from frozen deposits, and impacts on human existence. Degradation of ice-rich permafrost results in characteristic thermokarst landforms that are widespread in Central Yakutia. The Holocene thermokarst evolution is dominantly a climate-driven process. Permafrost thawing due to increased air temperatures in the early Holocene resulted in surface subsidence and the subsequent formation of thermokarst lakes and depressions (alases). In addition, the landscape in Central Yakutia is subject to strong short-term modifications by intensified land use and extreme weather events [Brouchkov et al., 2004; Fedorov & Kontantinov, 2009]. However, it is not sufficiently clear, how and when thermokarst depressions in Central Yakutia were formed or how they have evolved since the late Pleistocene-Holocene transition and secondly, which climatical, morphological or hydrological parameters are currently influencing thermokarst depression and lake dynamics. In particular, the anthropogenic aspect is of special interest as human existence in this populated region is strongly connected to the use of thermokarst depressions and lakes for agriculture, fishing and as water resource [e.g., Desyatkin, 1998] (Fig.1).