Fluctuations of glaciers and ice caps in cold mountain areas have been systematically observed for more than a century in various parts of the world and are considered to be highly reliable indications of worldwide warming trends (cf. Fig. 2.39a in IPCC 2001). Mountain glaciers and ice caps are, therefore, key variables for early-detection strategies in global climate-related observations. Advanced monitoring strategies integrate detailed observations of mass and energy balance at selected reference glaciers with more widely distributed determinations of changes in area, volume and length; repeated compilation of glacier inventories enables global representativity to be reached (IAHS(ICSI)/UNEP/UNESCO 1989; 1998; 2001; cf. Haeberli et al. 2000; 2002).