Glacier changes are among the clearest signals of ongoing warming trends existing in nature. Steps are now being undertaken to make worldwide glacier monitoring part of the Global Climate Observation System GCOS by WMO, ICSU, UNEP, and UNESCO. Such a worldwide collection of standardized observations includes repeated compilation of statistical information on the distribution and topographic characteristics of perennial surface ice in space (glacier inventories). Glacier inventory work is repeated at time intervals which are comparable to characteristic dynamic response times of mountain glaciers (a few decades) and helps with analysing and assessing changes at a regional scale.
The highest information density and most complete historical record exists in the European Alps. In Switzerland, a complete glacier inventory was compiled from aerial photography taken in 1973. As part of the National Research Programme 31 (NRP 31), this inventory was revised in detail and completed with a reconstruction of glacierization in 1850. Comparison of the two data bases together with long-term observations at individual sites and regional studies using more recent imagery indicates major mass losses with an acceleration tendency. Now the time has come to compile a new glacier inventory for the Swiss Alps. This task is greatly facilitated by the launching of the satellite Terra in October 1999. The GLIMS (Global Land Ice Monitoring from Space) project will use data from the radiometer ASTER to compile a snapshot of all land-ice masses at the beginning of the new millenium. The project proposed here enables Switzerland to take part in the GLIMS-project. The so-compiled Swiss Glacier Inventory 2000 will be the first product of the proposed research programme.
The methodological tool for efficiently compiling glacier inventories from satellite imagery will be the second product. Remote sensing at various scales (satellite imagery, aerophotogrammetry) and GIS technologies will be combined with digital terrain information in a fusion and downscaling approach to estimate the accuracy of multiple glacier classification algorithms and to reduce costs/time of compilation.
Based on the now available experience with existing inventories, a representative sample of glaciers will be classified and parameterized for further modelling of glacier changes. The basis of modelling with respect to a large number of roughly characterized glaciers has been developed as part of the NRP31. This modelling will be extended in view to determining regional glacier hazard potentials (ice avalanches, lake outbursts, debris flows) at high altitudes and, thereby, apply decisive findings of the NRP31.
The project proposed here is strongly connected to the Institute of Hydromechanics and Water Resources Management (IHW), Hydrology section of ETH Zurich. The GLIMS - Regional Centre will be run in close cooperation with the above. Additionally the results of this project will contribute to a hydrological modelling project and, vice-versa, the latter project will provide field measurements for the project proposed here.
Key words: Glacier, climate change, remote sensing, geographical information system, glacier inventories, fusion, downscaling.