Ice Sheet evolution in Patagonia and Northern Europe during the last ice age - Insights from numerical modelling

Abstract

During the Last Glacial Maximum (LGM, ~23–19 ka), large ice sheets covered much of the Northern Hemisphere and southern South America. Geochronological data indicate contrasting behaviours between the Patagonian Ice Sheet (PIS) and the Eurasian Ice Sheet Complex (EISC): the PIS reached its maximum during Marine Isotope Stage (MIS) 3, while the EISC expanded to its maximum during the LGM. This dissertation employs numerical ice sheet modelling (SICOPOLIS) and surface mass balance (SMB) analysis to explore the climatic conditions influencing these ice sheets across the last glacial cycle. Results show the PIS advanced during MIS4 and late MIS3–MIS2, driven by variations in integrated summer energy at mid-latitudes, with millennial-scale fluctuations linked to Dansgaard-Oeschger events. The study reveals that climate model limitations, such as low resolution and oversimplified topography, lead to inaccurate PIS simulations, often misrepresenting ice growth patterns. Offshore SST records from the southeastern Pacific more accurately capture the MIS3 expansion than Antarctic core-derived indices. For the EISC, SMB simulations highlight the dominant role of summer temperature in shaping maximum extent. Regional analysis shows strong correlations between SMB in different ice sheet sectors and climate conditions over the Greenland-Iceland-Norwegian and Labrador Seas. These findings underscore the need for high-resolution climate models and robust proxy integration to refine reconstructions of past ice sheet dynamics.