Climate and ground ice in the north of Western Siberia in the late Pleistocene and Holocene

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Abstract The combined application of paleocryological and palynological methods has revealed that the formation of polygonal wedge ice at the end of the Late Pleistocene and in the first half of the Holocene, including the main phase of peat accumulation and of the advance of the treeline into the tundra zone in the north of Western Siberia, occurred under conditions of severe continental climate. Mean annual air temperatures and permafrost temperatures were significantly lower than at present and thus caused an intensification of thermal contraction cracking and of ice wedge formation. Existing concepts of the Holocene Climatic Optimum in the north of Siberia as a period of significantly higher humidities, higher mean summer air temperatures and permafrost temperatures and of widespread degradation of the permafrost do not present a true picture of the reality of the geographical situation at the time.