Spatial distribution of mean winter air temperatures in S iberian permafrost at 20−18 ka BP using oxygen isotope data

Palaeotemperature reconstruction for the period of 20−18 ka BP in S iberia is here based on δ 18 O analysis and 14 C dating of large syngenetic ice wedges. Dozens of yedoma exposures, from Y amal P eninsula to C hukotka, have been studied. Snow meltwater is considered to be the main source of ice‐wedge ice. The modern relationship between δ 18 O composition of ice‐wedge ice and winter temperature is used as a base for reconstruction. In modern ice wedges (elementary veins that have accumulated during the last 60–100 years) δ 18 O fluctuates between −14 and −20‰ in western S iberia and between −23 and −28‰ in northern Yakutia. The trend in δ 18 O distribution in ice wedges dated at 20−18 ka BP is similar to the modern one. For example, the δ 18 O values in Late Pleistocene wedges are more negative going from west to east by 8–10‰, i.e. from −19 to −25‰ in western S iberian ice wedges to −30 to −35‰ in northern Y akutia. However, values are as high as −28 to −33‰ in north C hukotka and the central areas of the M agadan R egion and even as high as −23 to −29‰ in the east of C hukotka. The same difference between the oxygen isotope composition of ice wedges in the eastern and western regions of S iberian permafrost (about 8–10‰) is also preserved from 20−18 ka BP to the present: δ 18 O values obtained from large ice wedges from the L ate P leistocene vary from −19 to −25‰ in western Siberia to −30 to −35‰ in northern Y akutia. We conclude that, at 20−18 ka BP , mean J anuary temperatures were about 8–12° C lower (in C hukotka up to 17–18° C ) than at present.