Past continental shelf evolution increased Antarctic ice sheet sensitivity to climatic conditions

Area of Science:

• Paleoclimatology
• Glaciology
• Geophysics

Background:

• The Antarctic continental shelf has deepened over the past 34 million years due to ice sheet loading, thermal subsidence, and glacial erosion.
• Sedimentary records indicate a shift in the Antarctic Ice Sheet's (AIS) dynamical response to climate after the mid-Miocene Climate Optimum (≈15 Ma).

Purpose of the Study:

• To explore end-members of maximum Antarctic Ice Sheet extent using simulations of late-Pleistocene and mid-Miocene glaciations.
• To understand the fundamental dynamical differences in AIS behavior under varying atmospheric forcing, sea level, and continental shelf evolution.

Main Methods:

• Ice-sheet simulations for late-Pleistocene and mid-Miocene glacial periods.
• Analysis of sedimentary deposits to infer past Antarctic Ice Sheet dynamics.

Main Results:

• Significant dynamical differences in AIS behavior were identified based on atmospheric forcing, eustatic sea level, and continental shelf evolution.
• The AIS amplified its sensitivity to ocean forcing by eroding the continental shelf, likely altering its tipping points over time.

Conclusions:

• Past topographic and bathymetric reconstructions are lacking, leading to an incomplete understanding of the AIS's rapid response to past warm conditions.
• A better understanding of past AIS dynamics is crucial for constraining future ice sheet evolution and sea-level rise.