Concurrent Changepoints in Greenland Ice Core δ18 O records and the North Atlantic Oscillation over the Past Millennium

Abstract

Structural changes, or changepoints, coinciding in multiple ice core records over the Greenland Ice Sheet (GrIS) may reflect a widespread response of the GrIS to atmospheric forcing. Thus, to better understand how atmospheric circulation may regulate sudden changes in δ18O of Greenland precipitation, we seek synchronous changepoints occurring in ice core-derived δ18O time series across the GrIS and in the North Atlantic Oscillation (NAO) over the past millennium. By utilizing a Bayesian changepoint detection method, four changepoint horizons were revealed: at the beginning of the 20th century, in the late-15th century, and around the turn of the 11th and 10th centuries. Although the changepoints in ice core δ18O records exhibited distinctive spatial arrange-ments in each horizon, all corresponded to changepoints in the NAO, indicative of a consistent atmospheric influence on GrIS surface changes over the past millennium.