The role of ocean circulation and sea ice in abrupt climate change
Abrupt changes in Earth's climate have occurred repeatedly throughout the geological record. Evidence from paleoclimate data has revealed that climate changed most dramatically during the last glacial period, associated with the Dansgaard-Oeschger (D-O) events. These are characterized by large...
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The University of Bergen
2020
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ftunivbergen:oai:bora.uib.no:1956/21388 2023-05-15T16:28:44+02:00 The role of ocean circulation and sea ice in abrupt climate change Rheinlænder, Jonathan Winfield orcid:0000-0002-2544-2900 2020-01-06T12:57:53.741Z application/pdf https://hdl.handle.net/1956/21388 eng eng The University of Bergen Paper I: Jonathan W. Rheinlænder, Lars H. Smedsrud and Kerim H. Nisancioglu, Internal ocean dynamics as a driver for open-ocean polynyas in the Weddell Sea. The article is not available in BORA. Paper II: Jonathan W. Rheinlænder, David Ferreira, and Kerim H. Nisancioglu Topological constraints by the Greenland-Scotland Ridge on AMOC and climate. The article is not available in BORA. Paper III: Jonathan W. Rheinlænder, David Ferreira, and Kerim H. Nisancioglu The impact of vertical mixing on glacial ocean circulation and sea ice. The article is not available in BORA. container/d9/84/3d/f7/d9843df7-ec1f-4940-bff8-f3c2ea125e3e https://hdl.handle.net/1956/21388 In copyright http://rightsstatements.org/page/InC/1.0/ Copyright the Author. All rights reserved Doctoral thesis 2020 ftunivbergen 2023-03-14T17:41:42Z Abrupt changes in Earth's climate have occurred repeatedly throughout the geological record. Evidence from paleoclimate data has revealed that climate changed most dramatically during the last glacial period, associated with the Dansgaard-Oeschger (D-O) events. These are characterized by large and rapid fluctuations in North Atlantic climate, with regional warming of up to 15 degrees C over Greenland, within a few decades. The main hypotheses for these abrupt climate changes in the past, centers around changes in the Atlantic Meridional Overturning Circulation (AMOC) and its influence on poleward ocean heat transport. Recently, the role of sea ice has also been recognized as a critical player for the D-O events; linking the abrupt changes in Greenland temperature to a retreat of Northern Hemisphere sea ice, driven by internal variability of the coupled ice-ocean and atmosphere system. However, the mechanism for triggering rapid changes in sea ice, and how it is linked to ocean circulation changes, remains elusive. This thesis focuses on the interaction between ocean circulation, sea ice and high-latitude climate in the context of abrupt climate changes in the past. The main goal is to improve our understanding of how internal dynamics of the coupled climate system can lead to rapid and unforced changes in climate. The first part of this thesis explores the mechanism behind abrupt changes in sea ice by studying the formation of open-ocean polynyas in the Southern Ocean. The second and third part, focuses on the dynamics of large-scale ocean circulation and its sensitivity to ocean bathymetry and the distribution of diapycnal mixing in the ocean interior. We find that open-ocean polynyas in the Southern Ocean provide a mechanism to trigger abrupt sea ice retreat, similar to that seen during the last glacial period. These events drive increased bottom water formation, thereby impacting the large-scale ocean circulation. The formation of the polynya is preconditioned by a gradual build-up of subsurface heat and salt ... Doctoral or Postdoctoral Thesis Greenland North Atlantic Sea ice Southern Ocean University of Bergen: Bergen Open Research Archive (BORA-UiB) Greenland Southern Ocean |
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Open Polar |
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University of Bergen: Bergen Open Research Archive (BORA-UiB) |
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ftunivbergen |
language |
English |
description |
Abrupt changes in Earth's climate have occurred repeatedly throughout the geological record. Evidence from paleoclimate data has revealed that climate changed most dramatically during the last glacial period, associated with the Dansgaard-Oeschger (D-O) events. These are characterized by large and rapid fluctuations in North Atlantic climate, with regional warming of up to 15 degrees C over Greenland, within a few decades. The main hypotheses for these abrupt climate changes in the past, centers around changes in the Atlantic Meridional Overturning Circulation (AMOC) and its influence on poleward ocean heat transport. Recently, the role of sea ice has also been recognized as a critical player for the D-O events; linking the abrupt changes in Greenland temperature to a retreat of Northern Hemisphere sea ice, driven by internal variability of the coupled ice-ocean and atmosphere system. However, the mechanism for triggering rapid changes in sea ice, and how it is linked to ocean circulation changes, remains elusive. This thesis focuses on the interaction between ocean circulation, sea ice and high-latitude climate in the context of abrupt climate changes in the past. The main goal is to improve our understanding of how internal dynamics of the coupled climate system can lead to rapid and unforced changes in climate. The first part of this thesis explores the mechanism behind abrupt changes in sea ice by studying the formation of open-ocean polynyas in the Southern Ocean. The second and third part, focuses on the dynamics of large-scale ocean circulation and its sensitivity to ocean bathymetry and the distribution of diapycnal mixing in the ocean interior. We find that open-ocean polynyas in the Southern Ocean provide a mechanism to trigger abrupt sea ice retreat, similar to that seen during the last glacial period. These events drive increased bottom water formation, thereby impacting the large-scale ocean circulation. The formation of the polynya is preconditioned by a gradual build-up of subsurface heat and salt ... |
author2 |
orcid:0000-0002-2544-2900 |
format |
Doctoral or Postdoctoral Thesis |
author |
Rheinlænder, Jonathan Winfield |
spellingShingle |
Rheinlænder, Jonathan Winfield The role of ocean circulation and sea ice in abrupt climate change |
author_facet |
Rheinlænder, Jonathan Winfield |
author_sort |
Rheinlænder, Jonathan Winfield |
title |
The role of ocean circulation and sea ice in abrupt climate change |
title_short |
The role of ocean circulation and sea ice in abrupt climate change |
title_full |
The role of ocean circulation and sea ice in abrupt climate change |
title_fullStr |
The role of ocean circulation and sea ice in abrupt climate change |
title_full_unstemmed |
The role of ocean circulation and sea ice in abrupt climate change |
title_sort |
role of ocean circulation and sea ice in abrupt climate change |
publisher |
The University of Bergen |
publishDate |
2020 |
url |
https://hdl.handle.net/1956/21388 |
geographic |
Greenland Southern Ocean |
geographic_facet |
Greenland Southern Ocean |
genre |
Greenland North Atlantic Sea ice Southern Ocean |
genre_facet |
Greenland North Atlantic Sea ice Southern Ocean |
op_relation |
Paper I: Jonathan W. Rheinlænder, Lars H. Smedsrud and Kerim H. Nisancioglu, Internal ocean dynamics as a driver for open-ocean polynyas in the Weddell Sea. The article is not available in BORA. Paper II: Jonathan W. Rheinlænder, David Ferreira, and Kerim H. Nisancioglu Topological constraints by the Greenland-Scotland Ridge on AMOC and climate. The article is not available in BORA. Paper III: Jonathan W. Rheinlænder, David Ferreira, and Kerim H. Nisancioglu The impact of vertical mixing on glacial ocean circulation and sea ice. The article is not available in BORA. container/d9/84/3d/f7/d9843df7-ec1f-4940-bff8-f3c2ea125e3e https://hdl.handle.net/1956/21388 |
op_rights |
In copyright http://rightsstatements.org/page/InC/1.0/ Copyright the Author. All rights reserved |
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1766018417464180736 |