Over the past three decades, observations have shown that both the Antarctic and Greenland Ice Sheets have been losing mass at a fast pace. Glaciers and ice sheets have become today the largest contributors to sea level rise, but their contribution over the next century remains a key uncertainty in sea level rise projections. Understanding and reducing these uncertainties to improve the representation of past and future behavior of the ice sheets and their interactions with the other components of the Earth system remains scientifically and technically challenging.

The number of remote-sensing observations of polar ice sheets has followed an exponential growth over the past decade. These new observations offer a great opportunity for ice flow models to calibrate model parameters, validate simulation results and investigate physical processes for which only a limited number of direct observations exist. I will show a few examples of how such observations can be used in ice flow models to better understand processes poorly represented, better capture the observed trend in ice mass loss and ultimately improve ice sheet projections, using data assimilation and parameter estimate. The talk will conclude with some future research directions and new challenges.