The configuration of Northern Hemisphere ice sheets through the Quaternary

Christine L Batchelor,Andrea Manica,April S Dalton,Chris R Stokes,Mario Krapp,Della K Murton,Philip L Gibbard,Julian B Murton,Martin Margold

doi:10.1038/s41467-019-11601-2

Abstract

Our understanding of how global climatic changes are translated into ice-sheet fluctuations and sea-level change is currently limited by a lack of knowledge of the configuration of ice sheets prior to the Last Glacial Maximum (LGM). Here, we compile a synthesis of empirical data and numerical modelling results related to pre-LGM ice sheets to produce new hypotheses regarding their extent in the Northern Hemisphere (NH) at 17 time-slices that span the Quaternary. Our reconstructions illustrate pronounced ice-sheet asymmetry within the last glacial cycle and significant variations in ice-marginal positions between older glacial cycles. We find support for a significant reduction in the extent of the Laurentide Ice Sheet (LIS) during MIS 3, implying that global sea levels may have been 30–40 m higher than most previous estimates. Our ice-sheet reconstructions illustrate the current state-of-the-art knowledge of pre-LGM ice sheets and provide a conceptual framework to interpret NH landscape evolution.

Highlights

Empirical evidence relating to Northern Hemisphere (NH) ice sheets, together with the output from numerical models, from over 180 published studies is compiled for 17 preLGM time-slices that extend back to the Late Pliocene (Fig. 1, Supplementary Figures 1–10, Supplementary Tables 1–17)
Terrestrial evidence for glaciations older than 1 Ma, during the Early Pleistocene to Late Pliocene, is scarce and dated mostly by palaeo-magnetic methods[23,24]. These intervals are grouped into two broad time-slices: the early Matuyama magnetic Chron (1.78–2.6 Ma), which encompasses the onset of major NH glaciation recorded by terrestrial evidence, around 2.4–2.5 Ma;[14,25,26] and the late Gauss Chron (2.6–3.6 Ma), which includes the onset of major NH glaciation recorded by icerafted debris in ocean cores, around 2.6–2.7 Ma27,28 (Fig. 1c, Supplementary Figures 9 and 10)
This paper and the accompanying online database provide a synthesis of empirical data and modelled outputs relating to preLGM ice sheets, and should be viewed as new hypotheses relating to the likely ice-sheet extent at key time intervals through the Quaternary (Fig. 1, Supplementary Figures 2–10)

Summary

Introduction

Our understanding of how global climatic changes are translated into ice-sheet fluctuations and sea-level change is currently limited by a lack of knowledge of the configuration of ice sheets prior to the Last Glacial Maximum (LGM). 1234567890():,; The growth and decay of continental ice sheets have formed an integral part of the Earth’s climate system during the Late Cenozoic and over the last 2.6 Ma (the Quaternary Period), resulting in major fluctuations in global sea level[1]. Reconstructing the former extent of ice sheets is, vital to understand how global climatic changes are translated into ice-sheet fluctuations, providing important constraints for future predictions of sea-level change[2].

Objectives

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Results

Conclusion