Modeling the role of the last ice age for the present and future sea-level contribution from Antarctica

The project will encompass the numerical simulation of at least four glacial cycles of the Antarctic sheet-shelf system using the Parallel Ice Sheet Model (PISM). The objective of the research plan is to determine the role of the past development of the Antarctic Ice Sheet for its sea-level contribution of the past and future century. To this end we investigate the influence of past climate evolution, especially the last deglaciation, on its present dynamic state: The ongoing changes in terms of mass balance, disregarding anthropogenic climate change, during the 20th and 21st centuries are influenced by the history of the advance and retreat of the ice during the last glacial cycles. Instead of aiming at a best-guess simulation, we will work on providing an ensemble of model simulations that incorporates uncertainties from climate boundary conditions and internal process-modeling and ice parameter choices. Apart from answering the above mentioned research question concerning the influence of the history of the ice sheet on its present day dynamics, we will also take an important step towards a new generation of projections of future ice discharge from Antarctica: It is important to know how much sea-level contribution, if any, is not caused by anthropogenic climate change. The program encompasses the development and short-term testing of physical improvements to the model that are needed in order to perform four glacial cycles (4GC) simulations and to provide a comprehensive ensemble. The currently implemented climate boundary conditions, both for the upper surface of the ice sheet and the underside of the ice shelves in contact with the ocean, will be examined and expanded to be suitable for 4GC-simulations. Process-based model components, concerning the numerical representation of the transition zone between ice sheet and ice shelf will be evaluated and improved. High-resolution nested simulation approaches will be developed for PISM in order to better resolve these crucial zones in order the further close the gap between finite differences models like PISM using shallow approximations of the stress balance and higher-order models. Sensitivity tests within 4GC-simulations will shed light on how the above mentioned new methods, climate boundary conditions in general and internal model parameters, influence the 4GC-simulation and ultimately the modeled present day state. An ensemble selection process will take place, excluding those parameter and climate-boundary combinations that are not conform to available geologic data for the past and observations of the present day state of the Antarctic ice sheet. This can be thought of as a “blind selection” of the dynamic present-day state of the ice sheet. By that “dynamic state” we mean the responsiveness of the modeled ice sheet to external forcing, which can vary drastically among a set of modeled ice sheets that are quite similar with respect to vertical and horizontal ice extent. We will therefore provide an uncertainty range for Antarctica´s sea-level contribution in the 20th and 21th century caused by the ice-sheets history.


Aug 01, 2014 until Jul 31, 2017

Funding Agency

DFG - Deutsche Forschungsgemeinschaft

Funding Call

DFG-Schwerpunktprogramm 1158 "Antarktisforschung"


Anders Levermann