Vjeran Višnjević, Frederic Herman, Günther Prasicek

The Quaternary climate has been dominated by alternating glacial and interglacial periods. While the timing and extent of past ice caps are well documented, local variations in temperature and precipitation as a response to cyclic glaciations are not resolved. Resolving these issues is necessary for understanding regional and global climate circulation. In particular, how did the cold high-pressure zone above the Fennoscandian ice cap impact the position of the jet stream in Europe, and was there a change in the direction and the source of moister flow are still matter of discussions. Here we reconstruct climate conditions that led to the observed ice extent in the European Alps during the last glacial maximum (LGM). Using a new inverse method to reconstruct the spatially variable position of the equilibrium line altitude (ELA), we investigate whether southern shifts in the position of the Westerlies may have influenced the growth and retreat of the ice cap. We report inversion results that enable us to estimate the role of climate, inversion method parameters, ice dynamic, flexure and bedrock topography on the inferred equilibrium line altitude. Our main finding is the presence of a dominating W-E gradient in the position of the ELA during the LGM that does not require a shift of the westerlies during the LGM.