Concurrent Changepoints in Greenland Ice Core δ18O Records and the North Atlantic Oscillation over the Past Millennium

István Gábor Hatvani,Dániel Topál,Eric Ruggieri,Zoltán Kern

doi:10.3390/atmos13010093

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 arrangements in each horizon, all corresponded to changepoints in the NAO, indicative of a consistent atmospheric influence on GrIS surface changes over the past millennium.

Highlights

Atmospheric circulation overlying the Greenland Ice Sheet (GrIS) shows marked interannual-to-decadal oscillations arising from large-scale natural oceanic/atmospheric modes of variability [1,2,3] such as the North Atlantic Oscillation (NAO; [4])
We began by describing the timing of the events associated with synchronous changes in the GrIS ice core δ18 O records
This study shows the first joint assessment for detecting changepoint horizons in the ice core derived water stable isotope records with annual resolution available from the

Summary

Introduction

Atmospheric circulation overlying the Greenland Ice Sheet (GrIS) shows marked interannual-to-decadal oscillations arising from large-scale natural oceanic/atmospheric modes of variability [1,2,3] such as the North Atlantic Oscillation (NAO; [4]). Placing observed coupled changes in GrIS surface conditions and atmospheric circulation aloft into the context of paleoclimatic time scales is necessary to better understand the consistency of their co-variability with regard to synchronous sudden changes. A vast number of high-resolution ice core-derived paleoclimate proxy parameters are available from the GrIS [9,10,11], some of which approximate ambient temperatures—e.g., firn/ice δ18 O records [12]—that altogether offer insights into past Greenland changes beyond the observational era [13]. The water stable isotopes from firn and ice profiles are one of the most studied geochemical parameters when it comes to investigating past climates [12]

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