Ice Sheet Responses to Past and Current Climate Forcings Waleed Abdalati [[email protected]], Earth Science and Observation Center/CIRES, Department of Geography, University of Colorado, Boulder As little as a decade ago, it was believed that ice sheet responses to changes in climate occurred on time scales on the order of centuries to millennia. Observations of the past decade, however, have revealed that climate perturbations, combined with the geologic conditions of the ice sheets, lead to nearly immediate response times of as little as days or even hours. Much of our understanding of this short-term ice sheet-climate coupling has evolved as a result of satellite and airborne remote sensing techniques. The context, scale, and perspective provided by these observational capabilities are revolutionizing our understanding of the Greenland and Antarctic ice sheets, revealing changes that are in some cases much more dramatic than were ever expected. From collapsing ice shelves to accelerating outlet glaciers, and increasingly negative ice sheet mass balance, remote sensing capabilities are providing important insights into ice sheet behavior and their current and potential contributions for sea level rise. When coupled with in situ observations and robust process models, these large-scale four-dimensional observational capabilities are helping us understand the nature of the changing ice cover, the processes that govern it, and what the implications may be for life on Earth.