Insights into Glacial Terminations from a South Atlantic Perspective
The last two glacial terminations represent the most recent, and best documented, periods of Earth warming in the geological record. During these terminations atmospheric CO\textsubscript{2 }rose by approximately 100 ppm and global mean temperatures increased by 4-6\textsuperscript{o}C. Whilst the d...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/267478 2023-07-30T03:56:27+02:00 Insights into Glacial Terminations from a South Atlantic Perspective Roberts, Jenny 2017-09-30T09:33:01Z application/pdf https://doi.org/10.17863/CAM.13432 https://www.repository.cam.ac.uk/handle/1810/267478 en eng Trinity Earth Sciences University of Cambridge doi:10.17863/CAM.13432 https://www.repository.cam.ac.uk/handle/1810/267478 CC BY (Attribution) https://creativecommons.org/licenses/by/4.0/ Antarctic Intermediate Water Southwest Atlantic Paleoceanography Thesis Doctoral Doctor of Philosophy (PhD) PhD in Earth Sciences 2017 ftunivcam https://doi.org/10.17863/CAM.13432 2023-07-10T21:20:53Z The last two glacial terminations represent the most recent, and best documented, periods of Earth warming in the geological record. During these terminations atmospheric CO\textsubscript{2 }rose by approximately 100 ppm and global mean temperatures increased by 4-6\textsuperscript{o}C. Whilst the driver for these deglaciations ultimately derives from changes in the insolation forcing at the edge of the atmosphere, feedbacks within the Earth\textquoteright s climate system act to amplify these small external forcings tipping the Earth from a cold glacial climate state to a warm interglacial climate state. A key question in Quaternary climate science is understanding which feedbacks are important in regulating global climate on glacial-interglacial timescales. On this topic, the Southern Ocean has long been considered to be an important player in regulating atmospheric CO\textsubscript{2 } on glacial-interglacial timescales. This thesis investigates some of the hypothesised drivers of changes in atmospheric CO\textsubscript{2 } on glacial-interglacial timescales by generating high-resolution multi-proxy records from the Southern Ocean spanning the last two glacial terminations. In particular, I focus on changes in the structure, circulation and biological productivity within the sub-Antarctic zone. A change in the deep ocean density structure has been hypothesised to have resulted in the release of CO\textsubscript{2 } from the deep ocean. Centennial records from the sub-Antarctic are used to reconstruct deep and intermediate water density for the first time. I demonstrate that timing of the major breakdown in the density gradient of the ocean significantly lagged the breakdown in the chemical gradient, suggesting that changes in the deep ocean density structure were not the major driver of the deglacial rise in atmospheric CO\textsubscript{2 }. Changes in the density structure of the Southern Ocean likely had significant implications for global circulation. In particular, the flow of low salinity water through ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Southern Ocean Apollo - University of Cambridge Repository Antarctic Southern Ocean |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
Antarctic Intermediate Water Southwest Atlantic Paleoceanography |
spellingShingle |
Antarctic Intermediate Water Southwest Atlantic Paleoceanography Roberts, Jenny Insights into Glacial Terminations from a South Atlantic Perspective |
topic_facet |
Antarctic Intermediate Water Southwest Atlantic Paleoceanography |
description |
The last two glacial terminations represent the most recent, and best documented, periods of Earth warming in the geological record. During these terminations atmospheric CO\textsubscript{2 }rose by approximately 100 ppm and global mean temperatures increased by 4-6\textsuperscript{o}C. Whilst the driver for these deglaciations ultimately derives from changes in the insolation forcing at the edge of the atmosphere, feedbacks within the Earth\textquoteright s climate system act to amplify these small external forcings tipping the Earth from a cold glacial climate state to a warm interglacial climate state. A key question in Quaternary climate science is understanding which feedbacks are important in regulating global climate on glacial-interglacial timescales. On this topic, the Southern Ocean has long been considered to be an important player in regulating atmospheric CO\textsubscript{2 } on glacial-interglacial timescales. This thesis investigates some of the hypothesised drivers of changes in atmospheric CO\textsubscript{2 } on glacial-interglacial timescales by generating high-resolution multi-proxy records from the Southern Ocean spanning the last two glacial terminations. In particular, I focus on changes in the structure, circulation and biological productivity within the sub-Antarctic zone. A change in the deep ocean density structure has been hypothesised to have resulted in the release of CO\textsubscript{2 } from the deep ocean. Centennial records from the sub-Antarctic are used to reconstruct deep and intermediate water density for the first time. I demonstrate that timing of the major breakdown in the density gradient of the ocean significantly lagged the breakdown in the chemical gradient, suggesting that changes in the deep ocean density structure were not the major driver of the deglacial rise in atmospheric CO\textsubscript{2 }. Changes in the density structure of the Southern Ocean likely had significant implications for global circulation. In particular, the flow of low salinity water through ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Roberts, Jenny |
author_facet |
Roberts, Jenny |
author_sort |
Roberts, Jenny |
title |
Insights into Glacial Terminations from a South Atlantic Perspective |
title_short |
Insights into Glacial Terminations from a South Atlantic Perspective |
title_full |
Insights into Glacial Terminations from a South Atlantic Perspective |
title_fullStr |
Insights into Glacial Terminations from a South Atlantic Perspective |
title_full_unstemmed |
Insights into Glacial Terminations from a South Atlantic Perspective |
title_sort |
insights into glacial terminations from a south atlantic perspective |
publisher |
Trinity |
publishDate |
2017 |
url |
https://doi.org/10.17863/CAM.13432 https://www.repository.cam.ac.uk/handle/1810/267478 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
doi:10.17863/CAM.13432 https://www.repository.cam.ac.uk/handle/1810/267478 |
op_rights |
CC BY (Attribution) https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.13432 |
_version_ |
1772813301290369024 |