The patterns and drivers of recent outlet glacier change in East Antarctica

• Main Author: MILES, ALBERT,WILLIAM,JOHN
• Format: Thesis
• Language: unknown
• Published: 2017
• Subjects: East Antarctica; sea ice; landfast; Cook; glacier; Antarctic; West Antarctica; East Antarctic Ice Sheet; Greenland; Wilkes Land; Cook Glacier; Porpoise Bay; Antarc*; Antarctica; Ice Sheet; Sea ice
• Online Access: http://etheses.dur.ac.uk/12426/; http://etheses.dur.ac.uk/12426/1/Thesis_BM.pdf

West Antarctica and Greenland have made substantial contributions to global sea level rise over the past two decades. In contrast, the East Antarctic Ice Sheet (EAIS) has largely been in balance or slightly gaining mass over the past two decades. This is consistent with the long-standing view that the EAIS is relatively immune to global warming. However, several recent reports have highlighted instabilities in the EAIS in the past, and some numerical models now predict near-future sea level contributions from the ice sheet, albeit with large uncertainties surrounding the rates of mass loss. Using primarily remote sensing methods, this thesis aims to determine spatial and temporal patterns of outlet glacier change in the EAIS and assess the drivers and mechanisms of any changes in their dynamics. In doing so, it will also explore the wider debate surrounding the potential vulnerability of the ice sheet in the coming decades to centuries. Pan-ice sheet terminus mapping in 1974, 1990, 2000 and 2012 reveals significant decadal variability in the behaviour of the EAIS. The majority of outlet glaciers retreated between 1974 and 1990, before switching to a dominant advance phase from 1990-2000. This trend of outlet glacier advance largely continued between 2000 and 2012, with the exception of Wilkes Land, where 74% of glaciers retreated. It is hypothesized that this anomalous retreat is linked to a reduction in sea ice and associated impacts on ocean stratification. A more detailed examination of six glaciers in Porpoise Bay, Wilkes Land, reveals that large simultaneous calving events in January 2007 and March 2016, totalling ~2,900 km2 and 2,200 km2, were driven by the break-up of the multi-year landfast sea ice which usually occupies Porpoise Bay. However, these break-up events were driven by contrasting mechanisms. The 2007 break-up event is linked to an exceptionally warm December 2005 weakening the band of multi-year sea ice prior to its eventual break-up in the following summer. Whereas, the 2016 event is linked ...