Quaternary Antarctic Ice Sheet Dynamics

• Main Author: Sutter, Johannes
• Other Authors: Lohmann, Gerrit, Lemke, Peter
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2016
• Subjects: Antarctica; Sea Level; Climate Change; 500; 500 Science; ddc:500; Antarctic; Southern Ocean; The Antarctic; West Antarctic Ice Sheet; East Antarctic Ice Sheet; Antarc*; Antarktis*; Eisschild*; Ice Sheet; Ice Shelves
• Online Access: https://media.suub.uni-bremen.de/handle/elib/1085; https://nbn-resolving.org/urn:nbn:de:gbv:46-00105391-19

The Antarctic Ice Sheet (AIS) plays a major role in the evolution of Quaternary glacial interglacial cycles and in the global climate system in general. By a variety of ice ocean and ice atmosphere feedback processes, changes in the dynamics of the southern ice giant are felt throughout the globe. Ice cores drilled down to the bedrock of the East Antarctic Ice Sheet provide a glimpse into the climate history of the past one million years via water stable isotopes and trapped gasses conserved in the slow flowing ice (climate proxies). Dramatic changes in ice volume and extent characterize the evolution of the AIS during the last 130.000 years, affecting both Southern Hemisphere and global climate. A central protagonist in this history of the AIS is the West Antarctic Ice Sheet (WAIS), due to its unique setting extending into several ocean basins and thus being prone to destabilization triggered by warming of the Southern Ocean. The objective of this thesis is to shed light on the glacial interglacial dynamics of the AIS by means of 3D ice sheet modeling. The dynamic evolution of the WAIS during the Last Interglacial (LIG) and in the future is investigated and potential climate thresholds for an marine ice sheet collapse identified. Special attention is given to the role of basal melting underneath the ice shelves in the growth and decay of the WAIS. An ocean warming range of 2o 3 C is found to be sufficient to trigger an irreversible retreat of the marine ice sheet culminating in its complete collapse and a global Antarctic sea level contribution of up to 5m during the last interglacial as well as within the next millennia. It is found that the collapse depends on a complex interplay of precipitation patterns, bedrock topography, ocean bathymetry and ultimately Southern Ocean warming. Intrinsic timescales defined by the topographic features of the WAIS are found leading to a characteristic two phase collapse of the ice sheet. This thesis, for the first time, provides an estimate of LIG climate conditions required ...