Permafrost evidence for severe winter cooling during the Younger Dryas in northern Alaska

摘要

The Younger Dryas cold event, a rapid reversion toglacial climate conditions at the Pleistocene-Holocenetransition, has generally been attributed to the release ofmeltwater from the Laurentide Ice Sheet to the NorthAtlantic or Arctic oceans. The reaction of the NorthPacific region to this "shutdown" of the thermohalinecirculation in the North Atlantic during Younger Dryas islittle understood. In this paper, we present the firstradiocarbon-dated centennial-scale stable water isotoperecord from permafrost in northern Alaska. This LateGlacial winter climate reconstruction from Barrow icewedges demonstrates the existence of a Younger Dryascold event, formerly believed to be reduced or absent inthis area. Our stable isotope data display a gradual changeof the atmospheric moisture source conditions during theYounger Dryas, likely associated with the successive openingof the Bering Strait.