Mathieu Morlighem (UC Irvine) hosted by Ginny Catania The challenge of modeling ice sheets in a changing climate Abstract: Ice sheets are dynamic systems that interact with other components of the Earth System and are among the strongest contributors to sea level rise. Observations over the last three decades have shown that the Greenland and Antarctic Ice Sheets have been losing mass at an increasing rate. How the ice sheets respond to the warming of the ocean and the atmosphere has become today one of the most urgent questions in understanding the implications of global climate change. Numerical modeling is the only effective way of addressing this problem. Yet, despite significant improve¬ments in ice sheet models over the past decade, the predictive skills of the new generation of models remain limited over short time scales (tens to hundreds of years). The primary reasons for this lack of reliability are (1) the level of uncertainty in many important model inputs, such as bed topo-graphy, geothermal heat flux or ocean-induced melting patterns, and (2) poor understanding of physical processes such as iceberg calving. Here, we discuss the advent of the new generation of ice sheet models with a more complete physics, present some major challenges that we have overcome, and detail the future challenges of the ice sheet modeling community.