Glaciers integrate variations in climate over several different time scales and are thus used as indicators of both present and past climate change. It is however of importance to be able to correctly measure changes in the glaciers mass over time (the glaciers mass-balance), if one wishes to use the glaciers as climate indicators. The mass-balance of a glacier is a direct result of the glaciers ablation and accumulation. A glacier in equilibrium with its climate has an equal sized accumulation and ablation during the course of a year. This means that the mass-balance is zero and the glacier will not grow nor shrink over the years. The mass-balance is traditionally obtained by field measurements of the glaciers density and snow depth during...