Reconstruction of climate-glacier interaction on a centennial time scale

2019 - 2022

This project is part of the DFG Research Unit “Sensitivity of high Alpine geosystems to climate change since 1850” (SEHAG). With study sites in three high Alpine catchments (Martelltal, Kaunertal and Horlachtal), the overarching goal of SEHAG is to investigate to what extent the effects of documented atmospheric changes are detectable in glaciers, hydrology, geomorphic processes, soil and vegetation dynamics, and sediment transport, and how interactions between these geosystem components may enhance or attenuate climate change impacts.
Glaciers are typically situated in complex terrain that strongly interacts with the atmospheric processes which govern the exchange of energy and mass of a glacier with its surroundings. Glaciers therefore experience an expression of larger scale weather and climate patterns that is strongly influenced by the local scale. This local scale, however, is inadequately represented in climate data based on observations, reanalyses and models. In this project, we aim to quantify to how much of the total uncertainty of model-based glacier reconstructions stems from inherent glacier model errors, and how much from inadequate forcing data: (i) We will perform dynamical downscaling experiments of an ensemble of global reanalysis data sets using the Weather and Research Forecast Model (WRF) to produce temporally and spatially highly resolved data sets of the atmospheric state over the Alps which are representative of the small-scale climate processes relevant for the geosystem and specifically for glacier dynamics. These data sets will be validated using point observations from weather stations. (ii) With the Open Global Glacier Model (OGGM) we will reconstruct the evolution of glacier mass balance, runoff, ice flow, and geometry of all glaciers in the study catchments, including former glaciers that have now disappeared. The causes the causes of glacier change will be determined through sensitivity studies. (iii) We will quantify to which degree the uncertainty of glacier reconstructions can be reduced by forcing the glacier model with dynamically downscaled atmospheric fields by repeating glacier reconstruction and glacier uncertainty determination using the results of different intermediate steps in the downscaling.
The reconstruction of local scale climate variability and glacier change will improve our ability to attribute any changes in geosystem dynamics (investigated by other SEHAG projects) to atmospheric forcing.

Funding Agency: 
Deutsche Forschungsgemeinschaft (DFG)
Funding Amount: 
€319 000