Regional differences of mass balance and their impact on the past and future evolution of glaciers in Switzerland

Temporal glacier variations are among the clearest natural indicators of ongoing climate change. Continuous efforts in glacier monitoring have achieved long time-series of length variation, mass balance and volume change of glaciers. A detailed assessment in terms of regional differences and representativeness of individual data sets has, however, not yet been conducted despite a wealth of existing data.

Of several key parameters on glaciers, the mass balance most clearly reflects climatic variation. There is only a limited number of mass balance records available covering a relatively short time span. In order to interpret regional glacier changes, additional and extended time series are necessary.

However, a large amount of additional mass balance and climatological data exist in Switzerland.

The main goal of this project is to reconstruct past mass-balance time series in seasonal temporal resolution for different glaciers in the Swiss Alps over the last 100-150 years and both to identify and interpret regional differences. Beside direct observations of mass balance, based on in-situ measurements, indirect methods for their determination exist. Volume changes derived from repeated comparison of the surface topography determined for different years are related to glacier mass balance. Accumulation and ablation may be determined by using meteorological data and surface topography of the glacier. Data of volume changes with high temporal and spatial resolution allow the validation of the calculated mass balance. These reconstructed mass-balance time series will be used to force a numerical glacier flow model which will return the evolution of the glacier length. The
combined approach of reconstructed mass balances, the forward modeling of glacier evolution and the inverse modeling of observed glacier length fluctuation will provide more insights in the representativity of the recorded length change in terms of climate change.