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Title: Modelling stable water isotopes in ice and ocean cores during the quaternary
Author: Holloway, Max
ISNI:       0000 0004 6059 7398
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2016
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This thesis compares paleoclimate records with isotope-enabled paleoclimate model simulations. δ¹⁸0 against salinity and temperature relationships are investigated during periods of altered ice sheets, sea ice and meltwater input. We concentrate on 0, 21, 125 and 128 thousand years ago. Chapter 2 examines the use of δ¹⁸0 measurements in reconstructing salinity from ocean cores. Chapter 3 examines how Antarctic ice core δ¹⁸0 responds to changes in West Antarctic Ice Sheet (WAIS) morphology and sea ice extent. We find that ice sheet changes can decouple the δ¹⁸0-temperature relationship. The most significant contribution of this thesis focusses on explaining the last interglacial (LIG) δ¹⁸0 maximum, approximately 128 thousand years ago. Here, by replacing the WAIS with ocean and including the effects of WAIS meltwater, we provide a relatively realistic simulation of WAIS collapse. We find that a full WAIS collapse during the early LIG was unlikely. Instead a major reduction in sea ice, driven by bipolar seesaw warming of the Southern Hemisphere in response to circum-North Atlantic ice sheet melting, is a more likely explanation for the LIG isotope maximum. However, model simulations of 600 years duration, presented in Chapter 4, indicate that the bipolar seesaw mechanism only partially explains the observed isotope maximum. This leaves a significant portion of the observed Southern Ocean warming, estimated sea ice retreat and observed 6180 enrichment unaccounted for. It is currently unclear whether this result is repeatable using other General Circulation Models. The connectivity between the Southern Ocean, sea ice and the Antarctic ice sheet are suggested as a high-priority areas for future study to reconcile the remaining model-data disagreement.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available