Decadal-scale onset and termination of Antarctic ice-mass loss during the last deglaciation

Michael E Weber,Chris J Fogwill,Zoë A Thomas,Chris S M Turney,Nicholas R Golledge

doi:10.1038/s41467-021-27053-6

Abstract

Emerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries. Unfortunately, the short observational record cannot resolve the tipping points, rate of change, and timescale of responses. Iceberg-rafted debris data from Iceberg Alley identify eight retreat phases after the Last Glacial Maximum that each destabilized the AIS within a decade, contributing to global sea-level rise for centuries to a millennium, which subsequently re-stabilized equally rapidly. This dynamic response of the AIS is supported by (i) a West Antarctic blue ice record of ice-elevation drawdown >600 m during three such retreat events related to globally recognized deglacial meltwater pulses, (ii) step-wise retreat up to 400 km across the Ross Sea shelf, (iii) independent ice sheet modeling, and (iv) tipping point analysis. Our findings are consistent with a growing body of evidence suggesting the recent acceleration of AIS mass loss may mark the beginning of a prolonged period of ice sheet retreat and substantial global sea level rise.

Highlights

Emerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries
The marinebased Wilkes Land basin of the East Antarctic Ice Sheet (EAIS), which holds an equivalent of 3–4 m global mean sea-level rise (GMSLR), has sectors exposed to marine ice-sheet instability that have the potential to discharge ice for centuries to millennia[3]
No specific iceberg calving mechanism was included, the temporal phasing of AIS mass loss arising from the combination of applied environmental forcings and independent age determination bears extremely close correspondence to the phasing, shape, and relative magnitudes of iceberg-rafted debris (IBRD) fluxes recorded in Iceberg Alley[14] (Fig. 2a, b)

Summary

Introduction

Emerging ice-sheet modeling suggests once initiated, retreat of the Antarctic Ice Sheet (AIS) can continue for centuries. The decadal-scale onset and termination of AIS mass loss is consistent over all eight deglacial AID events, regardless of changing environmental, sea-level, and grounding line conditions.

Results

Conclusion