The World Glacier Monitoring Service has compiled worldwide data on glacier changes for more than 120 years. Together with its National Correspondents in more than 30 countries, the international service just published a new comprehensive analysis of global glacier changes. In this study, observations of the first decade of the 21st century (2001-2010) were compared to all available earlier data from in-situ, air-borne, and satellite-borne observations as well as to reconstructions from pictorial and written sources.