Thermokarst as a short-term permafrost disturbance, Central Yakutiaстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The widespread occurrence of alas depressions in Central Yakutia is not necessarily evidence of
modern thermokarst activity. Typically, a near-surface ‘shielding layer’, formed as the result of deep
thaw in exceptionally warm years, protects underlying icy sediment from thaw. In spite of current
climatic warming, there is no noticeable increase in regional thermokarst in Central Yakutia. Periodic
forest fires significantly increase soil thermal conductivity and progressive soil salinization is
occurring; however, these are insufficient to cause thaw of the underlying icy sediments. Instead,
active thermokarst should be regarded as a short-term catastrophic process. Use of the Kudryavtsev
algorithm indicates that the depth of thaw beneath a water body in Central Yakutia can reach 8–10m
within 50 years, and 20þ m within 300 years. Field observations show that current thermokarst has a
tendency for fast (5–10þ cm/year) subsidence.