Modelling glaciers and ice sheets

The German term “ewiges Eis” (in a rough translation: everlasting ice) is used as a synonym for glaciers in the Alps. Glaciers and – in a more natural way – ice sheets for long have been considered to be static objects that do not change a lot over generations. Recent observations, in particular after the start of modern remote sensing techniques (airborne and from satellites) in the late decades of the last century clearly show that ice that has been built up over glacial cycles, in a highly non-linear response can be released into the oceans in a fraction of this timespan, thereby contributing to rapid sea-level rise. With plausible prognostic model scenarios indicating a rise of global sea-level as much as 1 m by the end of this century, this is one of the most imminent threats linked to climate change. In this seminar we want to highlight the aspects of computer models used to analyse the dynamics of ice masses spanning several spatial scales, reaching from football-field sized glaciers to continental ice sheets. We will (in a possibly non-mathematical way) discuss the material properties of ice, different approximations to the governing equations of ice flow and their implementation as high performance computing models. Along examples from the community ice-sheet simulation package Elmer/Ice (http://elmerice.elmerfem.org) we present techniques for coupling ice-sheet models to other components of Earth system models (atmosphere, permafrost, ocean). Special focus in these discussions shall be put on marine ice sheet dynamics.