Glacier mass balance: A global outlook

Glaciers exist on all continents of the world at altitudes between sea level and >8000 m, in widely varying climatic settings. The total number of glaciers and ice caps outside the Greenland and Antarctic ice sheets is estimated at close to 200,000, covering approximately 700,000 km2. Satellite mapping has greatly improved estimates of the glacier cover in remote areas and estimates of the total volume of glaciers and ice caps are continually being improved. Only a few dozen long-term mass balance records from ground-based measurements on individual glaciers exist, but airborne and remote-sensing platforms are allowing estimates of ice-volume changes over glaciated regions on continental scales. Similarly, mass balance modelling is being extended from individual glaciers to entire mountain ranges. Mass loss from glaciers is occurring in all mountain regions and their projected total volume decline by the end of this century ranges between 10 and 50%, depending on scenarios. This session will highlight recent glacier changes in different parts of the world and discuss methods for constraining observational uncertainties. Presentations in this session can cover, but are not limited to, the following topics:

• Reconstructing past glacier extent and changes;
• Mass balance measurement results, using both glaciological and geodetic methods;
• Modelling future mass balance and runoff;
• Coupling of glacier mass balance models with ice flow models;
• Improving estimates of the effects of debris cover, dust deposition, internal melting, surface and firn hydrology and drifting snow on mass balance.
• Education and capacity building programmes on glacier changes worldwide