Widespread increase in dynamic imbalance in the Getz region of Antarctica from 1994 to 2018

Heather L Selley,Jan Wuite,Lin Gilbert,Tae-Wan Kim,Andrew Shepherd,Anders Kusk,Pierre Dutrieux,Anna E Hogg,Thomas Slater,Dana Floricioiu,Thomas Nagler,Stephen Cornford

doi:10.1038/s41467-021-21321-1

Abstract

The Getz region of West Antarctica is losing ice at an increasing rate; however, the forcing mechanisms remain unclear. Here we use satellite observations and an ice sheet model to measure the change in ice speed and mass balance of the drainage basin over the last 25-years. Our results show a mean increase in speed of 23.8 % between 1994 and 2018, with three glaciers accelerating by over 44 %. Speedup across the Getz basin is linear, with speedup and thinning directly correlated confirming the presence of dynamic imbalance. Since 1994, 315 Gt of ice has been lost contributing 0.9 ± 0.6 mm global mean sea level, with increased loss since 2010 caused by a snowfall reduction. Overall, dynamic imbalance accounts for two thirds of the mass loss from this region of West Antarctica over the past 25-years, with a longer-term response to ocean forcing the likely driving mechanism.

Highlights

The Getz region of West Antarctica is losing ice at an increasing rate; the forcing mechanisms remain unclear
The slowest moving glaciers are found in the far East of the Getz drainage basin, where flow unit 1 located to the West of Martin Island, and flow unit 3 located to the West of Wright Island, flow at a speeds of 174 ± 12 m/year and 183 ± 14 m/year, respectively (Table 1 and Supplementary Fig. 1)
Two previous studies have measured the change in speed of glaciers in the Getz drainage basin, with the largest increase in ice flow observed behind Siple Island and at the far West of the sector between 2007/8 to 2014/15

Summary

Introduction

The Getz region of West Antarctica is losing ice at an increasing rate; the forcing mechanisms remain unclear. Dynamic imbalance accounts for two thirds of the mass loss from this region of West Antarctica over the past 25-years, with a longer-term response to ocean forcing the likely driving mechanism. Satellite data have shown that in Antarctica the dynamic ice loss (6.3 ± 1.9 mm sea level equivalent (sle)) is 86% greater than the modest reduction in surface mass (0.9 ± 1.1 mm sle) since the 1990s22. Both long-term and emerging new dynamic signals must be accurately measured in order to better understand how ice sheets will change in the future. Ice flows from the ice sheet into the Getz Ice Shelf through 14 distinct glaciers that extend ~145 km inland, and flow at average speeds of over 500 m/year at the grounding line (Fig. 1a)

Methods

Results

Conclusion