ИСТИНА

The Arctic currently experiences a pronounced and unprecedented warming. This highly dynamic response on changes in climate forcing and the global impact of the Arctic water, carbon and energy balance make the Arctic a key region to study past, recent and future climate changes. Polygonal ice wedges are a widespread permafrost feature in the Arctic tundra lowlands. Ice wedges are formed by the repeated filling of thermal contraction cracks by snow melt water, which quickly refreezes at negative ground temperatures and forms ice veins. As the seasonality of frost cracking and infill is generally related to winter and spring, respectively, the isotopic composition of wedge ice is indicative of past climate conditions during the cold season. δ18O of ice is interpreted as proxy for surface air temperatures in the region of precipitation. We consider different stratigraphic units of Holocene and modern ice wedges (e.g. river terraces, top of Ice Complex, thermokarst basin deposits) as well as ice-wedge dating and chronological approaches. The derived winter climate trends for the Mid to Late Holocene are compared to other Arctic paleoclimate records, climate forcing as well as climate model results.