ABSTRACT
This chapter reviews the polar orbiting satellites observations, along with other contemporary measurements that together describe the health of the Greenland and Antarctic ice sheets. Systematically observing the health of ice sheets forms part of wider efforts to monitor Earth's Polar Regions, and aids projections of the evolution of the Earth system. Earth's two Polar ice sheets are the largest reservoirs of fresh water on the planet; greater by two orders of magnitude than the sum total of all glaciers and ice caps. Greenland is primarily a terrestrial-based ice sheet, grounded on bedrock above sea level. Most estimates of mass loss from the Greenland and Antarctic ice sheets are derived from one of three techniques – the mass budget, altimetry and gravimetry methods. In Antarctica, the primary need is to understand the drivers of variability within the surrounding ocean, and the influence that these changes may have upon ice dynamics, through complex interactions at the ice-ocean interface.
