Mass Balance Studies
A mass balance study is how scientists put a number on whether a glacier gained or lost ice in a given year. It is the most basic and useful measurement in glaciology, the bedrock of everything from sea- level forecasts to water-supply planning.
The traditional method
A network of "ablation stakes" — long bamboo or aluminium poles drilled into the ice — track surface melt. At the end of summer the amount of stake exposed above the surface is measured: that height equals the melt at that point.
Snow accumulation is measured in snow pits — vertical excavations down through the winter snow to the previous summer surface. Density measurements convert depth into water equivalent.
Multiplying the area covered by each measurement by its local balance, then summing across the glacier, gives total mass balance for the year. Some glaciers have unbroken records going back to the 1950s.
Modern additions
Aircraft and satellite altimetry (ICESat, CryoSat, ICESat-2) now measure surface height changes from space. Repeat photogrammetry from drones and structure-from-motion from photographs both supplement ground stakes. Gravimetric satellites (GRACE/FO) measure the total mass change of ice sheets.
The longest records
Storglaciaren (Sweden), Hintereisferner (Austria), Sarennes (France) and Storbreen (Norway) all hold 70+ year continuous records. The WGMS (World Glacier Monitoring Service) compiles data from over 200 reference glaciers.
What the data show
Almost every monitored glacier outside the central Karakoram has lost mass over the past 40 years. The cumulative loss is accelerating. 2022 and 2023 set new records for the European Alps.
How visitors can help
Many monitoring programmes accept citizen science contributions — photographs from fixed viewpoints, time-stamped images at standard locations. The Swiss GLAMOS programme and Norway's NVE accept these through public portals.
Explore on the map
The interactive map shows monitoring station locations with links to the latest published mass balance data — useful for trip planning if you want to visit a "well-measured" glacier.