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Utilizing Paleoceanographic Proxies in the High Latitude North Atlantic to Better Understand Meridional Overturning Circulation Dynamics During the Last Deglaciation.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Utilizing Paleoceanographic Proxies in the High Latitude North Atlantic to Better Understand Meridional Overturning Circulation Dynamics During the Last Deglaciation./
作者:	Ingalsbe, Tara A.
面頁冊數:	1 online resource (101 pages)
附註:	Source: Masters Abstracts International, Volume: 77-09.
Contained By:	Masters Abstracts International77-09.
標題:	Paleoclimate science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10029476click for full text (PQDT)
ISBN:	9781339530321

Utilizing Paleoceanographic Proxies in the High Latitude North Atlantic to Better Understand Meridional Overturning Circulation Dynamics During the Last Deglaciation.
Ingalsbe, Tara A.

Utilizing Paleoceanographic Proxies in the High Latitude North Atlantic to Better Understand Meridional Overturning Circulation Dynamics During the Last Deglaciation. - 1 online resource (101 pages)

Source: Masters Abstracts International, Volume: 77-09.

Thesis (M.S.)--Florida Gulf Coast University, 2015.

Includes bibliographical references

The Meridional Overturning Circulation (MOC) is a critical component of the global climate system. Research indicates that disruptions in MOC strength were responsible for widespread abrupt climate changes across the Northern Hemisphere during the last deglaciation. In particular, Heinrich Stadial 1 (HS1) (~18 ka) and the Younger Dryas (YD) (~12.5 ka), were characterized by ice rafting, abrupt cooling, and weakening of the MOC. Whereas the Bolling Allerod (BA) interval (~14.3 ka), was characterized by a decrease in ice rafting, abrupt warming, and strengthening of the MOC. The climatic drivers associated with these abrupt climate events are still not fully understood. Previous studies suggest a warming of surface and subsurface waters ~1-2 kyr prior to HS1 may have triggered ice sheet instability and subsequently the ice rafting associated with HS1. Furthermore, these studies suggest a weakening of Atlantic Meridional Overturning Circulation (AMOC), as a result of freshwater input from ice sheet instability, triggered Northern Hemisphere cooling. This study utilizes paleoceanographic proxies including, percent ice rafted debris (IRD), benthic foraminifera δ13C signatures, benthic foraminifera δ18O signatures, and planktonic foraminifera abundances, from high latitude North Atlantic deep-sea sediment cores to better understand past MOC dynamics associated with HS1. Our IRD and planktonic foraminifera abundance records suggest HS1 may have been divided into two ice rafting phases (i.e. HS1a and HS1b), each preceded by a warming of sea surface temperatures (SSTs). An abrupt decrease in δ13 C values after HS1a at ~16.67 ka implies a reduction in deep-water formation or ventilation and therefore AMOC slowdown or shutdown throughout the remainder of HS1. Our δ18O record suggests this reduction in deep-water formation and sustained weakening of AMOC may have been the result of decreased water density from continuous lateral injection of freshwater mixed downward at locations away from our site. Comparison of our records to previously published data may suggest that surface warming triggered ice sheet instability and subsequently HS1 associated ice rafting. Moreover, we suggest increased freshwater input from ice sheet instability lead to a weakening of AMOC resulting in cooling of the Northern Hemisphere.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9781339530321Subjects--Topical Terms:

3173835
Paleoclimate science.
Subjects--Index Terms:

Abrupt climate changeIndex Terms--Genre/Form:

542853
Electronic books.

Utilizing Paleoceanographic Proxies in the High Latitude North Atlantic to Better Understand Meridional Overturning Circulation Dynamics During the Last Deglaciation.
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504 $a Includes bibliographical references
520 $a The Meridional Overturning Circulation (MOC) is a critical component of the global climate system. Research indicates that disruptions in MOC strength were responsible for widespread abrupt climate changes across the Northern Hemisphere during the last deglaciation. In particular, Heinrich Stadial 1 (HS1) (~18 ka) and the Younger Dryas (YD) (~12.5 ka), were characterized by ice rafting, abrupt cooling, and weakening of the MOC. Whereas the Bolling Allerod (BA) interval (~14.3 ka), was characterized by a decrease in ice rafting, abrupt warming, and strengthening of the MOC. The climatic drivers associated with these abrupt climate events are still not fully understood. Previous studies suggest a warming of surface and subsurface waters ~1-2 kyr prior to HS1 may have triggered ice sheet instability and subsequently the ice rafting associated with HS1. Furthermore, these studies suggest a weakening of Atlantic Meridional Overturning Circulation (AMOC), as a result of freshwater input from ice sheet instability, triggered Northern Hemisphere cooling. This study utilizes paleoceanographic proxies including, percent ice rafted debris (IRD), benthic foraminifera δ13C signatures, benthic foraminifera δ18O signatures, and planktonic foraminifera abundances, from high latitude North Atlantic deep-sea sediment cores to better understand past MOC dynamics associated with HS1. Our IRD and planktonic foraminifera abundance records suggest HS1 may have been divided into two ice rafting phases (i.e. HS1a and HS1b), each preceded by a warming of sea surface temperatures (SSTs). An abrupt decrease in δ13 C values after HS1a at ~16.67 ka implies a reduction in deep-water formation or ventilation and therefore AMOC slowdown or shutdown throughout the remainder of HS1. Our δ18O record suggests this reduction in deep-water formation and sustained weakening of AMOC may have been the result of decreased water density from continuous lateral injection of freshwater mixed downward at locations away from our site. Comparison of our records to previously published data may suggest that surface warming triggered ice sheet instability and subsequently HS1 associated ice rafting. Moreover, we suggest increased freshwater input from ice sheet instability lead to a weakening of AMOC resulting in cooling of the Northern Hemisphere.
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538 $a Mode of access: World Wide Web
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653 $a Abrupt climate change
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