Glacial Isostatic Adjustment in Antarctica
Abstract:In order to determine the distribution of present-day ice mass change across the Antarctic Ice Sheet it is first necessary to remove the geodetic signal of past ice mass change. This signal arises due to the ongoing process of Glacial Isostatic Adjustment (GIA), which has traditionally been estimated by modelling the response of the Earth system to ice-sheet changes during a glacial cycle.
Reconstructions of ice-sheet change are typically based on field observations relating to past ice extent and thickness, although a more recent approach has involved the use of ice-sheet models, and even coupled ice-sheet – GIA models, to reconstruct the ice-sheet history in areas where field constraints are sparse. Both methods have their limitations and in this presentation I will highlight the advantages of each and compare recently-published models to assess our current state of knowledge in the field of Antarctic GIA. I will also briefly discuss the motivation behind active areas of model development, which include the consideration of lateral variations in Earth structure and feedbacks between solid Earth, ice sheet and ocean processes.
Finally, I will assess the suitability of the various data sets that are used to constrain or test Antarctic GIA models, and I will explain how combinations of data are being used to isolate the GIA signal independently of traditional modelling assumptions. Despite the clear benefits of this approach for the purposes of quantifying present-day ice mass change, it is still crucial to be able to model how GIA processes will evolve in the future. The motivation for this goal is provided by recent modelling studies, which suggest that GIA processes will be modified by, and are capable of influencing, the future dynamics of the Antarctic Ice Sheet.