Modelling the evolution of the global climate and the eurasian ice sheet during the last deglaciation

• Main Author: van Aalderen, Victor
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Université Paris-Saclay, Sylvie Charbit
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2023
• Subjects: Modelisation; Barents-Kara; Deglaciation; Transient simulation; Coupled model; Marine Ice sheet; Modélisation; Déglaciation; Simulation transitoire; Modèle couplé; Calotte marine; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarc*; Antarctic; Antarctica; Ice Sheet; Ice Shelves; West Antarctica
• Online Access: https://theses.hal.science/tel-04431549; https://theses.hal.science/tel-04431549/document; https://theses.hal.science/tel-04431549/file/127013_VAN_AALDEREN_2023_archivage.pdf

The marine West Antarctic ice sheet is characterized by being largely in contact with the ocean. The latest observations reveal an acceleration in its mass loss over the last few decades, mainly due to increased melting under floating ice shelves. However, its future evolution remains highly uncertain, due to our poor understanding of the physical processes at play between the ice sheet and the ocean.The last deglaciation (21 ka-11 ka) is one of the most recent major climatic changes in our history. This period is marked by an increase in global atmospheric temperatures and the melting of the North American and Eurasian ice sheets. The study of the Barents-Kara Ice Sheet (BKIS), which covered the Barents and Kara Seas during the Last Glacial Maximum (LGM, 21 ka) and was an integral part of the Eurasian Ice Sheet, is of particular interest because of its common features with present-day West Antarctica. Identifying the mechanisms responsible for its retreat allows to provide information to better understand the West Antarctic behavior within under present and future climatic conditions.The impact of climate on the evolution of a marine ice sheet depends on two main processes: The surface mass balance, depending on atmospheric temperatures and precipitation, and melting under floating ice, related to oceanic temperatures and salinity. In order to identify the mechanisms triggering the BKIS retreat, I used the GRISLI2.0 ice-sheet model to analyse the ice-sheet response to climate perturbations at the LGM. This study highlighted the key role of atmospheric temperatures in triggering the melting of the ice sheet via surface melting, while ocean temperatures had only a limited impact despite a large part of BKIS being in contact with the ocean. I also identified that the total retreat of BKIS could be attributed to a mechanical instability at the grounding line, caused by a decrease in ice thickness resulting from an increase in surface melting.In order to better understand the impact of ice sheets on the global ...