Climate warming over the 20th century has forced dramatic changes of the Greenland Ice Sheet (GrIS). Satellite observations have revealed increased flow of the glaciers to the sea [Rignot et al., 2008], increased surface melting [Steffen et al., 2004], lowering of the Ice Sheet surface [Zwally and Giovinetto, 2001], retreat of the glaciers' fronts [Box et al., 2006], and gravity anomaly related to ice mass loss [Velicogna and Wahr, 2006]. These changes have led to a reduction in the mass of the GrIS and a consequent rise in global sea level. With enough ice to raise global sea levels by over 7 metres, future changes could have a dramatic societal and economic impact. Runoff from the GrIS, for example, has the potential to modify patterns of global ocean circulation, with profound consequences on the Earth's system heat transport. Earth observation satellites provide a way to measure essential climate variables over large areas and with a frequency that allows us to understand and quantify the changes affecting the GrIS. Satellites provide, for example, datasets to understand the mechanisms by which mass is being lost and how the GrIS responds to the forcing of heat transport by the atmosphere and the ocean. The purpose of GreenSAR is to quantify the degree of mass imbalance of the GrIS by exploiting Earth Observation datasets, from past, present, and future satellite missions, with an emphasis on the novel TanDEM-X and CryoSat-2 missions. The TanDEM-X and CryoSat-2 missions will be used to determined the Digital Elevation Model of the area with enhance precision. The dataset will be used to test new concepts and techniques to better characterise mass imbalance. The outcome of this work will provide a comprehensive understanding of the mass transfer between the GrIS and the ocean, and an understanding of feedback processes that will provide an
improved capacity to predict future changes of the GrIS and its contribution to global sea level.