Exploring the Suitability of the CMIP5 Ensemble for Forcing the BISICLES Ice Sheet Model in the Amundsen Sea, West Antarctica

  • Alanna Alevropoulos-Borrill

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

The Amundsen Sea, West Antarctica, contains some of the fastest retreating ice streams in the world. Studies have proposed that the ice streams in the region could be subject to unabated and irreversible retreat, given that large extents of the region are grounded on retrograde bedrock, below sea level and thus could be susceptible to marine ice sheet instability. Ocean forced basal melting of ice shelves, determined predominantly by the temperature of the water masses interacting with the ice shelves, is the primary mode of mass loss from the region; given that melt induced thinning impacts the stability and position of the grounding line. Understanding the dynamic ice sheet response to changes in local ocean temperature offers a means to explore the projected mass loss contribution to sea level rise, under a warming climate.

Performance metrics for 27 CMIP5 AOGCMs have been calculated in order to identify a subset of models that best reproduce observations of ocean temperature in the Southern Ocean. Projected ocean temperature in the ASE over the 21st century, as produced by the subset, have been used to calculate a projected melt rate forcing for ASE glaciers. Melt rate forcings have been applied to the BISICLES ice sheet model to project the response of the ASE to changing climate. Accounting for the uncertainties associated with the model set-up, two sets of values for the ice stiffening factor and basal traction coefficient were used. Projected sea level contribution from ASE glaciers ranges between -0.02 and 12.3 cm by the end of the 21st century. Sea level rise estimates are found to be more sensitive to chosen parameter sets than the range of projected melt rate forcings, indicating that ice sheet model internal uncertainty exceeds the uncertainties associated with the choice of AOGCM.
Date of Award23 Jan 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorRory J Bingham (Supervisor) & A J Payne (Supervisor)

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