Talik

Due to climate fluctuations or changes, some permafrost regions may develop an unfrozen layer between the seasonal thawing and freezing surface layer and the permafrost. This layer is called a supra-permafrost ("above the permafrost") talik; it differs from traditional taliks, which are usually associated with water bodies, in that a supra-permafrost talik occurs because the ground that thaws in summer does not fully refreeze in winter. Calculations show that climate warming induces supra-permafrost taliks in moderately cold regions. In much colder regions, warming causes a deeper summer thaw without forming a talik layer, whereas in warm, shallow permafrost regions, permafrost quickly disappears. This type of talik has recently been observed in Russia. Over time and with continued increases in air temperature or snow depth, this talik layer becomes progressively thicker, and the deep permafrost layer eventually vanishes. Findings from a scientific study suggest a more widespread occurrence of open taliks within fault zones and areas influenced by large rivers.