European Alpine ice-field dynamics in context of past rapid climate change

Ice-sheet and glaciers constitute an essential component of the climate system and the main storage of freshwater on Earth. Regions particularly sensitive to climate change, the nature and magnitude of their responses to anthropogenic disturbances remain largely uncertain despite the associated challenges (melting ice and reduction of Earth's albedo, contribution to sea level rise, modifications of the oceanic circulation, etc.). In this context, studying the response of the cryosphere to past climate change can give valuable insights about its future evolution. The rapid temperature variations that occurred during the last glacial period are of specific interest for this purpose.

The Late Pleistocene (129-12 ky BP) is indeed marked by abrupt climate oscillations between relatively cold (stadial) and warm (interstadial) conditions in the Northern Hemisphere occurring at millennial time scale. These Dansgaard-Oeschger cycles (D-O) are responsible for strong sub-orbital climate variability, typically about 50% of glacial-interglacial amplitude in Greenland temperature (1). Although the driving mechanisms of D-O remain unclear, changes in the Atlantic Meridional Overturning Circulation are usually invoked for explaining these events, with oscillations between strong and weak transport modes (occurring either spontaneously or in response to external forcing (2)).

Our work analyse the European Alps ice field dynamics in response to rapid climate perturbations during the last glacial cycle. Most modelling experiments on this region focus on the reconstruction of the ice-sheet extent during the Last Glacial Maximum, but studies on the impact of D-O like events are less common. Following an approach tested over the Northern Hemisphere (3), we force the ice-sheet model GRISLI over the Alps during Marine Isotope Stage 3 (60-27 ky BP) with downscaled Paleoclimate Modelling Intercomparison Project climate data. Using two indexes, associated with orbital and millennial-scale variability and respectively applied to i) an Interglacial-LGM anomaly field ii) an AMOC with and without freshwater flux anomaly field, the method allows to take into account the different spatial patterns resulting from orbital and millennial climate fluctuations. The gap between the spatial resolutions of the Global Climate Models simulations and GRISLI is bridged using the downscaling model GeoDS, based on topographical and large scale circulation information.

 

 

(1) Wolff et al. (2010) https://doi.org/10.1016/j.quascirev.2009.10.013

(2) Li and Born (2019) https://doi.org/10.1016/j.quascirev.2018.10.031

(3) Banderas et al. (2015) https://doi.org/10.5194/gmd-11-2299-2018

(4) Brenner et al. (preprint) https://doi.org/10.5194/egusphere-2025-3617