Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle
The Greenland ice core record shows large and abrupt temperature increases that interrupted the cold climate of the last glacial period. These events, known as Dansgaard-Oeschger (D-O) events have been linked with climate records from North Atlantic and Nordic Seas sediments. Mechanisms determining...
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ftunivbergen:oai:bora.uib.no:1956/18841 2023-05-15T16:00:37+02:00 Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle Wille, Snorre Birkelund 2019-11-20 application/pdf https://hdl.handle.net/1956/18841 eng eng The University of Bergen https://hdl.handle.net/1956/18841 Copyright the Author. All rights reserved N. pachyderma D-O Dangsgaard-Oeschger Heinrich event Mg/Ca Temperaturendringer Overflatetemperatur https://data.ub.uio.no/realfagstermer/c011425 https://data.ub.uio.no/realfagstermer/c001133 756199 Master thesis 2019 ftunivbergen 2023-03-14T17:40:45Z The Greenland ice core record shows large and abrupt temperature increases that interrupted the cold climate of the last glacial period. These events, known as Dansgaard-Oeschger (D-O) events have been linked with climate records from North Atlantic and Nordic Seas sediments. Mechanisms determining the timing and amplitude of the Greenland temperature signal are thought to comprise variations in oceanic heat transport resulting from freshwater perturbations and variations in the Nordic Seas sea ice extent. While most studies on the near-surface Nordic Seas role in D-O events have been conducted in the south-eastern part of the Nordic Seas, I here present the first near-surface Mg/Ca temperature record over D-O events from the Denmark Strait. The record is coupled with δ18O and δ13C records obtained from the shells of the planktonic foraminiferal species Neogloboquadrina pachyderma and covers the interval Greenland Interglacial 9 (GI9) to Greenland Interglacial 8 (GI8) with 30-year temporal resolution. Two different cleaning protocols were applied prior to Mg/Ca measurement: the “Cd-cleaning” method and the “full-cleaning” method. Ratios of Al/Ca and other elemental ratios of potential contaminants decrease to some extent after the “full-cleaning” method compared with the “Cd-cleaning” method, yet the different cleaning methods yield similar results in terms of Mg/Ca. Mg/Ca reconstructed temperatures are largely in agreement with temperature reconstructions in the south-east Nordic Seas indicating that planktonic Mg/Ca temperature reconstruction is feasible during the last glacial period in the Denmark Strait. Subsurface waters were relatively warm during Heinrich Stadial 4 (HS4) with temperatures at ~4-5°C while δ18Osw and δ13C were low. Together, this suggests that the subsurface waters were covered by a lid of fresher surface water and sea ice. Over the transition to GI8, temperatures dropped by ~3°C, δ18Osw increased by ~1‰, and δ13C increased by ~0.3‰ indicating a reorganization of the upper water column. ... Master Thesis Denmark Strait Greenland Greenland ice core ice core Neogloboquadrina pachyderma Nordic Seas North Atlantic Sea ice University of Bergen: Bergen Open Research Archive (BORA-UiB) Greenland |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
topic |
N. pachyderma D-O Dangsgaard-Oeschger Heinrich event Mg/Ca Temperaturendringer Overflatetemperatur https://data.ub.uio.no/realfagstermer/c011425 https://data.ub.uio.no/realfagstermer/c001133 756199 |
spellingShingle |
N. pachyderma D-O Dangsgaard-Oeschger Heinrich event Mg/Ca Temperaturendringer Overflatetemperatur https://data.ub.uio.no/realfagstermer/c011425 https://data.ub.uio.no/realfagstermer/c001133 756199 Wille, Snorre Birkelund Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle |
topic_facet |
N. pachyderma D-O Dangsgaard-Oeschger Heinrich event Mg/Ca Temperaturendringer Overflatetemperatur https://data.ub.uio.no/realfagstermer/c011425 https://data.ub.uio.no/realfagstermer/c001133 756199 |
description |
The Greenland ice core record shows large and abrupt temperature increases that interrupted the cold climate of the last glacial period. These events, known as Dansgaard-Oeschger (D-O) events have been linked with climate records from North Atlantic and Nordic Seas sediments. Mechanisms determining the timing and amplitude of the Greenland temperature signal are thought to comprise variations in oceanic heat transport resulting from freshwater perturbations and variations in the Nordic Seas sea ice extent. While most studies on the near-surface Nordic Seas role in D-O events have been conducted in the south-eastern part of the Nordic Seas, I here present the first near-surface Mg/Ca temperature record over D-O events from the Denmark Strait. The record is coupled with δ18O and δ13C records obtained from the shells of the planktonic foraminiferal species Neogloboquadrina pachyderma and covers the interval Greenland Interglacial 9 (GI9) to Greenland Interglacial 8 (GI8) with 30-year temporal resolution. Two different cleaning protocols were applied prior to Mg/Ca measurement: the “Cd-cleaning” method and the “full-cleaning” method. Ratios of Al/Ca and other elemental ratios of potential contaminants decrease to some extent after the “full-cleaning” method compared with the “Cd-cleaning” method, yet the different cleaning methods yield similar results in terms of Mg/Ca. Mg/Ca reconstructed temperatures are largely in agreement with temperature reconstructions in the south-east Nordic Seas indicating that planktonic Mg/Ca temperature reconstruction is feasible during the last glacial period in the Denmark Strait. Subsurface waters were relatively warm during Heinrich Stadial 4 (HS4) with temperatures at ~4-5°C while δ18Osw and δ13C were low. Together, this suggests that the subsurface waters were covered by a lid of fresher surface water and sea ice. Over the transition to GI8, temperatures dropped by ~3°C, δ18Osw increased by ~1‰, and δ13C increased by ~0.3‰ indicating a reorganization of the upper water column. ... |
format |
Master Thesis |
author |
Wille, Snorre Birkelund |
author_facet |
Wille, Snorre Birkelund |
author_sort |
Wille, Snorre Birkelund |
title |
Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle |
title_short |
Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle |
title_full |
Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle |
title_fullStr |
Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle |
title_full_unstemmed |
Near-surface temperature changes in the Denmark Strait over a Dansgaard-Oeschger cycle |
title_sort |
near-surface temperature changes in the denmark strait over a dansgaard-oeschger cycle |
publisher |
The University of Bergen |
publishDate |
2019 |
url |
https://hdl.handle.net/1956/18841 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Denmark Strait Greenland Greenland ice core ice core Neogloboquadrina pachyderma Nordic Seas North Atlantic Sea ice |
genre_facet |
Denmark Strait Greenland Greenland ice core ice core Neogloboquadrina pachyderma Nordic Seas North Atlantic Sea ice |
op_relation |
https://hdl.handle.net/1956/18841 |
op_rights |
Copyright the Author. All rights reserved |
_version_ |
1766396627447185408 |