Comparing three different methods to model scenarios of future glacier change in the Swiss Alps

Ongoing atmospheric warming causes rapid shrinking of glaciers in the European Alps, with a high chance of their near-complete disappearance by the end of the 21st century. Here we present a comparison of three independent approaches to model the possible evolution of the glaciers in the Swiss Alps over the 21st century. The models have different levels of complexity, work at a regional scale and are forced with three scenarios of temperature increase (low, moderate, high). The moderate climate scenario gives an increase in air temperature of similar to 2 degrees C and similar to 4 degrees C for the two scenario periods 2021-50 and 2070-99, respectively, resulting in an area loss of 60-80% by 2100. In reality, the shrinkage could be even faster, as the observed mean annual thickness loss is already stronger than the modelled one. The three approaches lead to rather similar results with respect to the overall long-term evolution. The choice of climate scenarios produces the largest spread (similar to 40%) in the final area loss, while the uncertainty in present-day ice-thickness estimation causes about half this spread.