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Abstract:
Reliable mass loss projections are needed to anticipate the economic, societal and ecological consequences of 21st century glacier retreat. The field of large- and global-scale glacier modelling has already experienced great advances, but due to the scale of application several physical processes are not yet explicitly accounted for, with dynamical instabilities being a prime example. The dramatic down-stream mass transport associated with a glacier surge typically leads to glacier advance as well as thinning in upper regions and thickening in the ablation area, thus triggering a mass balance elevation feedback. While surge-type behaviour has only been documented for about 1% of glaciers worldwide, they tend to cluster together in specific regions – possibly impacting regional mass balance estimates. In this study we leverage a multidecade collection of multisource digital elevation models to extract geometry changes over a selection of Svalbard's known surge-type glaciers. The derived area-elevation distributions are then imposed on open-source large-scale glacier evolution model PyGEM to simulate glacier evolution over the same period. Results are compared to default simulations without any surge-related elevation changes. Although simple in nature this approach provides a first-order assessment on the relevance of dynamic instabilities for regional, century-scale mass balance estimates.
