Beschreibung:
Abstract. It is standard to compare climate model results coveringthe past millennium and reconstructions based on various archives in orderto test the ability of models to reproduce the observed climate variability.Up to now, glacier length fluctuations have not been used systematically inthis framework even though they offer information on multi-decadal tocentennial variations complementary to other records. One reason is thatglacier length depends on several complex factors and so cannot be directlylinked to the simulated climate. However, climate model skill can bemeasured by comparing the glacier length computed by a glacier model drivenby simulated temperature and precipitation to observed glacier lengthvariations. This is done here using the version 1.0 of the Open Global GlacierModel (OGGM) forced by fields derived from a range of simulations performedwith global climate models over the past millennium. The glacier model isapplied to a set of Alpine glaciers for which observations cover at leastthe 20th century. The observed glacier length fluctuations aregenerally well within the range of the simulations driven by the variousclimate model results, showing a general consistency with this ensemble ofsimulations. Sensitivity experiments indicate that the results are much moresensitive to the simulated climate than to OGGM parameters. This confirmsthat the simulations of glacier length can be used to evaluate the climatemodel performance, in particular the simulated summer temperatures thatlargely control the glacier changes in our region of interest. Simulatedglacier length is strongly influenced by the internal variability in thesystem, putting limitations on the model–data comparison for some variableslike the trends over the 20th century in the Alps. Nevertheless,comparison of glacier length fluctuations on longer timescales, for instancebetween the 18th century and the late 20th century, appear lessinfluenced by the natural variability and indicate clear differences in thebehaviour of the various climate models.