An Oxygen-Isotope Paleothermometer from Ice in Siberian Permafrost

There is a clear linear relationship between mean annual (or seasonal) air temperature at the Earth's surface and the mean oxygen isotopic composition of precipitation in polar regions. Whereas this relationship is well preserved in polar ice caps, it may not be in permafrost because freshly deposited snow in permafrost areas is subjected to great deflation and drifting by wind. Moreover, melting and freezing within the snow cover and the active layer can lead to isotopic fractionation. The δ18O of recent ground ice also depends on its geomorphic context and on the lithology (content of organic matter) of ice-containing sediments. Nevertheless, mean cold-season air temperature near the ground surface and δ18O in recent ground ice are highly correlated. Therefore, the δ18O of ground ice (ice cement and segregated ice) in permafrost areas can be used for paleoclimatic reconstructions.