Synopsis (short abstract)Changes in glaciers provide some of the clearest evidence of climate change, constitute key variables for early-detection strategies in global climate-related observations, and have the potential to cause serious impacts on sea level, the terrestrial water cycle and societies dependent on glacier melt water (GCOS 2004). Perennial surface ice on land includes glaciers and ice caps as well as the two continental ice sheets with their ice shelves, with fundamental differences in t ime-scales and processes involved. Due to their large areas and volumes, the two continental ice sheets in Greenland and Antarctica actively influence the global climate and react to climatic changes over time-scales of millennia. On the other hand, glaciers and ice caps with their smaller volumes and areas typically react much faster (few decades) to climatic changes.