Antarctic Ice Sheet Elevation Impacts on Water Isotope Records During the Last Interglacial

Sentia Goursaud,Andrew Pauling,Eric Wolff,Max Holloway,Eric J. Steig,Louise Sime,Paul Valdes

doi:10.1029/2020gl091412

Abstract

AbstractChanges of the topography of the Antarctic Ice Sheet (AIS) can complicate the interpretation of ice core water stable isotope measurements in terms of temperature. Here, we use a set of idealized AIS elevation change scenarios to investigate this for the warm Last Interglacial (LIG). We show that LIG δ18O against elevation relationships is not uniform across Antarctica and that the LIG response to elevation is lower than the preindustrial response. The effect of LIG elevation‐induced sea ice changes on δ18O is small, allowing us to isolate the effect of elevation change alone. Our results help to define the effect of AIS changes on the LIG δ18O signals and should be invaluable to those seeking to use AIS ice core measurements for these purposes. Especially, our simulations strengthen the conclusion that ice core measurements from the Talos Dome core exclude the loss of the Wilkes Basin at around 128 kyr.

Highlights

The size and configuration of the Antarctic Ice Sheet (AIS) varies in response to mass balance (Scambos et al, 2017) and ice dynamics
We show that Last Interglacial (LIG) δ18O against elevation relationships is not uniform across Antarctica and that the LIG response to elevation is lower than the preindustrial response
The LIG forcing, with no AIS elevation change, induces a mean annual Antarctic warming of 0.9 ± 0.6°C compared to PI (Supporting information Table S2) and precipitation increases of 0.6 ± 1.3 mm/month

Summary

Introduction

The size and configuration of the Antarctic Ice Sheet (AIS) varies in response to mass balance (Scambos et al, 2017) and ice dynamics. Geological data indicate that the WAIS expanded during the Last Glacial Maximum (LGM, approximately 21 kyears BP [ka]) (Bentley et al, 2014; Conway et al, 1999) and likely reduced during warmer interglacials (DeConto & Pollard, 2016; Dutton et al, 2015; Kopp et al, 2009, 2013; McKay et al, 2012; Scherer et al, 1998; Steig et al, 2015). Last Interglacial (LIG) changes in insolation are known to directly impact polar sea ice extent (Guarino et al, 2020; Kageyama et al, 2020)

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Results

Conclusion