ANTBASE

The objective of the research is to better understand the mechanism of the marine ice-sheet instability (MISI) in three spatial dimensions. The focus of the systematic investigation lies on the sub-glacial bed geometry, a key element for the stability of ice-sheet-shelf systems such as the Antarctic Ice Sheet (AIS). A main goal of the project is to find out whether critical thresholds exist for geometric parameters beyond which such systems cannot remain stable once their grounding line retreats onto an inland down-sloping (retrograde) bed section. These parameters include, but are not limited to, the width of the sub-glacial bed trough, the height and the steepness of the trough as well as the slope of the retrograde bed section.

The program encompasses: 1) the extension of the numerical model PISM to enhance the representation of ice flow through deep and narrow bed troughs; subsequent sensitivity analysis and model comparison; 2) the design of an ensemble of idealized bed topographies that represents the diverse regions of the AIS that are potentially prone to the MISI mechanism; 3) conducting conceptual perturbation experiments to infer possible critical geometric stability thresholds and to investigate their dependency on other geometric parameters; an enhanced stability assessment of potentially MISI-prone Antarctic regions. The objectives of the proposed research project are in various aspects consistent with the scientific goals of the Priority Program of the German Research Foundation SPP1158. Essential parts of three out of the four research topics concerning the role of Antarctica in the Earth system to be addressed in the SPP phase 2013-2018 are covered by different parts of this proposal.