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

Over the past 34 Million years, the Antarctic continental shelf has gradually deepened due to icesheet loading, thermal subsidence, and erosion from repeated glaciations. The deepening that isrecorded in the sedimentary deposits around the Antarctic margin indicates that after the mid-MioceneClimate Optimum (≈15 Ma), Antarctic Ice Sheet (AIS) dynamical response to climate conditionschanged. We explore end-members for maximum AIS extent, based on ice-sheet simulations of alate-Pleistocene and a mid-Miocene glaciation. Fundamental dynamical differences emerge as aconsequence of atmospheric forcing, eustatic sea level and continental shelf evolution. We show thatthe AIS contributed to the amplification of its own sensitivity to ocean forcing by gradually expandingand eroding the continental shelf, that probably changed its tipping points through time. The lackof past topographic and bathymetric reconstructions implies that so far, we still have an incompleteunderstanding of AIS fast response to past warm climate conditions, which is crucial to constrain itsfuture evolution.