Thermal state uncertainty assessment of glaciers and ice sheets: Detecting promising Oldest Ice sites in Antarctica

• Main Author: Van Liefferinge, Brice
• Other Authors: Pattyn, Frank, Tison, Jean-Louis, Debaille, Vinciane, Ritz, Catherine, Goelzer, Heiko
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universite Libre de Bruxelles 2018
• Subjects: Glaciologie; Ice sheet; Thermal state; Antarctica; Oldest Ice; Paleo-climate; basal temperature; englacial temperature; McCall; Antarc*; glacier; glaciers; ice core; Ice Sheet; Alaska
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/268026; https://dipot.ulb.ac.be/dspace/bitstream/2013/268026/4/Brice_dissertation.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/268026/3/Brice_dissertation_contents.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/268026/5/ContratVanLiefferinge.pdf

In a warming world, glaciers and ice sheets have an increasingly large influence on the environment, particularly through their contribution to sea level rise. Their response to anthropogenic climate change, in addition to natural variability, has a critical impact on dependent populations and will be key to predict future climates. Understanding the past natural transitions is also important as if the natural variability of the climate system is not well understood, we stand little change of accurately predicting future climate changes, especially in the context of rapid global warming. Ice cores represent the best time capsules for the recovery of paleo-climate informations. For that, the recovery of a suitable 1.5 million-year-old ice core in Antarctica is fundamental to better understand the natural climate reorganisation which occurred between 0.9 and 1.2 Ma. Constraining the englacial and basal temperature evolution of glaciers and ice sheets through time is the first step in understanding their temporal stability and therefore potential impacts on climate. Furthermore, obtaining the best constraints on basal conditions is essential as such million-year-old ice will be located very near to the bedrock, where the thermal regime has the strongest impact. However, measurements of current englacial and basal temperature have only been obtained at a few drill sites for glaciers and ice sheets. We must therefore turn to thermodynamical models to provide theoretical and statistical constraints on governing thermal processes. Thermodynamical models rely on a suite of governing equations, which we describe in this thesis. Our first study area is the McCall glacier, in Alaska (USA), where we show that the glacier cooled down in the warming climate of the last 50 years using a 1D thermodynamical model. We calculate the present-day englacial temperature distribution using recently acquired data in the form of englacial temperature measurements and radio-echo sounding surveys of the glacier. We show the important of ...