Assessing climatic control on erosion dynamics in alpine glacial cirques: evidence from the Neoglacial and Younger Dryas periods

Glacial cirques are key indicators of interactions between glaciers, climate, and topography. Moraine formation in glacial cirques is mainly influenced by periglacial and subglacial erosion processes, glacier dynamics, and topography. The intensity and spatio-temporal variability of erosion processes are climate-driven, yet climate is rarely considered in moraine formation. In this study, moraines formed during periods of glacier advances in several high-altitude cirques of the Mont Blanc, Aiguilles Rouges, and Gran Paradiso massifs were used as proxies for erosion to assess climate influence. We compared moraines from two periods: the Younger Dryas (cold and dry) and the Neoglacial (temperate and humid). A PDD glacial model was used to calibrate climate variations for these two periods relative to a reference period (1979–2014). Denudation rates were calculated from moraine volumes derived from high-resolution LiDAR DEM. Two extreme moraines formation-time hypotheses allowed the calculation of minimum and maximum values: 0.05 to 0.11 mm·a –1 and 0.10 to 0.23 mm·a –1 during the Younger Dryas; 0.12 to 0.45 mm·a –1 and 0.24 to 0.90 mm·a –1 during the Neoglacial. Furthermore, denudation rates correlated positively with mean annual temperature and precipitation in the studied cirques. These results could highlight those climatic parameters exert both spatial and temporal control on erosion in glacial cirques, with erosion being significantly accentuated under more temperate and humid climates compared to colder and dryer climates.