Response of the East Antarctic Ice Sheet to past and future climate change

Abstract

Preface: The East Antarctic Ice Sheet (EAIS) contains the vast majority of Earth's glacier ice (~52 metres sea-level equivalent), but is often viewed as less vulnerable to global warming than the West Antarctic or Greenland ice sheets. However, some regions of the EAIS have lost mass over recent decades, prompting the need to re-evaluate its sensitivity to climate change. Here we review the EAIS's response to past warm periods, synthesise current observations of change, and evaluate future projections. Some marine-based catchments that underwent significant mass loss during past warm periods are currently losing mass, but most projections indicate increased accumulation across the EAIS over the 21st Century, keeping the ice sheet broadly in balance. Beyond 2100, high emissions scenarios generate increased ice discharge and potentially several metres of sea-level rise within just a few centuries, but substantial mass loss could be averted if the Paris Agreement to limit warming below 2°C is satisfied.

Antarctic ice stream thickening under Pliocene warmth

“…Areas where the ice sheet was largely grounded below sea level are thought to have collapsed or retreated significantly, producing a steeper elevation profile [5,21,25,26]. The response of sectors that lie mostly above sea level, however, is largely unknown due to a lack of empirical evidence [27].…”

“…The potential for mass gains in regions of the AIS under warm periods needs to be well understood and constrained. This is because, in current projections, increased accumulation under a warmer climate partially offsets the loss of grounded ice from the WAIS and elsewhere [32], and the balance between current surface mass balance gains and dynamic losses is highly uncertain [27]. Antarctic ice stream thickening under Pliocene warmth…”

“…The steep and variable topography of DML, however, is not captured by continent-scale ice sheet models. Furthermore, recently discovered areas where the subglacial topography is overdeepened are also not included is most recent models [27,33]. These models are usually run at low spatial resolutions to achieve long simulation times, and consequently cannot represent regional patterns of ice dynamics, especially over areas of steep subglacial topography [34,35].…”

“…As in atmosphere and ocean models, the artificial smoothing of topography due to low spatial resolution prevents coarse-resolution ice sheet models from properly capturing regional topographically controlled dynamics [34][35][36]. In the case of ice sheet models, the inclusion of overdeepened subglacial topographies is detrimental for a proper assessment of whether marine ice sheet instability might occur in a retreating ice stream [27]. We show here that a proper representation of subglacial topography is critical to assess an ice stream's response to climate change, and that geological reconstructions might not accurately reflect the future response of an ice stream.…”

Temporal variations of surface mass balance over the last 5000 years around Dome Fuji, Dronning Maud Land, East Antarctica

“…Although in-situ observations (e.g., snow stake measurements), remote sensing observation (e.g., Velicogna et al, 2020) and regional climate models (e.g., Mottram et al, 2021) are useful for evaluating the spatiotemporal changes in AIS MB and SMB, they are available only over the last few decades. However, the AIS also changes in much longer time scales than those covered by the direct observations (e.g., Colleoni et al, 2018), the long-term records of the SMB are needed to better understand the AIS mass changes (Stokes et al, 2022). In this study, we use the term accumulation or accumulation rate to refer to positive SMB, because the long-term SMB is generally positive on the interior part of AIS.…”