Ensemble statistics of a geometric glacier length model

A third-order linear glacier length model is used to analyze if the retreat of Hintereisferner in the Austrian Alps over the past 160 years is exceptional, or lies within the range of the natural variability inherent to a stationary climate. A detailed uncertainty analysis takes into account glacier geometry, model parameters and initial conditions. A Monte Carlo ensemble strengthens the result that the observed retreat cannot be explained by natural variability and therefore affirms regional climate change. Finally the observed temperature trend at Hintereisferner lies outside the range of natural variability from an ensemble of climate models, but is consistent with the modeled range of responses to anthropogenic forcing.