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Title: The past relationship between temperature and sea level - from proxy records and ice sheet modelling
Author: Gasson, Edward G. W.
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Due to current uncertainties about the response of the ice sheets to anthropogenic climate forcing, there has been a growing interest in what the palaeo-record can tell us about the past response of the ice sheets to natural climate forcings. Direct qualitative and quantitative inferences have been made based on the past relationships between climate and sea level (which parallels ice sheet changes). Here we attempt to define better the past relationship between temperature and sea level. We first review existing temperature and sea level records, with a discussion of uncertainty in each of these datasets. We then synthesise the sea level and temperature data and test plausible forms for the sea level versus temperature relationship over the past 50 million years. We suggest that a nonlinear form for this relationship is evident in the data, which can be explained by the different glacial thresholds for Northern Hemisphere and Southern Hemisphere glaciation and the ice sheet carrying capacity of the Antarctic continent. We next perform ice sheet model simulations of the large ice sheets that either exist today(the East Antarctic ice sheet) or have existed in the past (the Northern Hemisphere ice sheets),focusing on past periods of large-scale change to these ice sheets. We use our simulations of the Northern Hemisphere ice sheets during the last glacial cycle to test and refine our modelling approach. We then investigate ice sheet hysteresis and the different thresholds for glaciation and deglaciation; this may limit the usefulness of using data from the Cenozoic, which is broadly a period of cooling, to make inferences about the future ice sheet response to ongoing warming. Finally we compare our model results with the earlier data synthesis and a recent study of the past relationship between atmospheric CO2 and sea level on long timescales.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available