Aurora Basin, the Weak Underbelly of East Antarctica

Abstract

The East Antarctic Ice Sheet (EAIS) has the potential to raise global sea levels by ∼52 m.Here, we model the evolution of select EAIS catchments to 2100 using three basal melt rate parameterizations and force our model with surface mass balance and ocean thermal anomalies from 10 global climate models. While the domain loses mass under low-emission scenarios, it gains ∼10-mm sea-level rise equivalent ice volume (SLRe) under high-emission scenarios. The primary region of thinning is within 50 km upstream of Totten Glacier's grounding line. Totten's glacial discharge is modulated by the migration of its grounding line, which is sensitive to brief intrusions of ocean water at temperatures higher than present. Once the grounding line is dislodged, Totten's ice velocity increases by up to 70% of present-day values, resulting in ∼6-mm SLRe loss from this sector. Plain Language SummaryPredicting how much the East Antarctic Ice Sheet (EAIS) will contribute to global sea-level rise is critical to the welfare of the global community. In our study, we model a large sector of EAIS to 2100 using a variety of different ocean melting representations and include both ocean temperature and snowfall predictions taken from two suites of climate model output. We find that by 2100, increases in snowfall outweigh increases in ice loss, and this sector of the EAIS will be responsible for a 10-mm decrease in global sea level under the highest climate warming scenarios. We find that Totten Glacier is most at risk to enhanced ocean warming, with the southernmost portion of this glacier acting as an important control on whether it loses ice or remains at its present-day configuration. If this portion of Totten is melted, this glacier may lose enough ice mass to raise global sea levels by 6mm by 2100.

Widespread Grounding Line Retreat of Totten Glacier, East Antarctica, Over the 21st Century

“…In the latter experiments, water is diverted west toward the region of outflow and does not induce melting directly at the grounding line (Figure S8). These rumples have been cited as a pinning point of TG in both observational and modeling studies Pelle et al, 2020;Roberts et al, 2018); however, the findings presented here suggest that these topographic highs serve the dual-purpose of acting as both a pinning point and barrier to warm water inflow.…”

“…Recent modeling studies have found that changes in sub-shelf ocean conditions are the primary driver of the observed dynamic changes TG has been experiencing over the past two decades (Gwyther et al, 2018;Pelle et al, 2020;Roberts et al, 2018). These studies, however, do not capture the full impact of changing sub-shelf ocean conditions on the system due to their use of simplified parameterizations of sub-ice shelf basal melt and/or fixed ice sheet geometry.…”

Grounding line retreat and tide-modulated ocean channels at Moscow University and Totten Glacier ice shelves, East Antarctica

“…As the weak underbelly of East Antarctica, Wilkes Land has been losing mass at accelerated rates due to warm water intrusion (Rignot et al, 2019;Pelle et al, 2020). This paper is the first comprehensive investigation of both short-term and long-term GL changes on Totten and Moscow University Glaciers.…”

Fine‐Scale Geothermal Heat Flow in Antarctica Can Increase Simulated Subglacial Melt Estimates

“…The timing of rapid glacier retreat and ice mass loss from key outlet basins in Antarctica constitutes the greatest uncertainty in estimates of future sea level rise (IPCC, 2021). The Aurora Subglacial Basin (ASB), East Antarctica, has significant potential to contribute to sea level rise (Pelle et al., 2020), containing approximately 7 m of sea‐level equivalent ice (Morlighem et al., 2020), of which 3.5 m is grounded below sea level (Greenbaum et al., 2015). The ASB has dominated recent ice mass loss from East Antarctica, losing 20 ± 14 Gt year −1 of ice between 2003 and 2019 (Smith et al., 2020).…”