Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth?
Highlights • Prominent North Atlantic sea surface cooling and freshening of ~3.5 °C and ~0.7‰ during ~3.65–3.5 Ma. • Surface cooling and freshening inline with a decrease of benthic δ13C records from South Atlantic Ocean sites. • Surface cooling and freshening at the same time as sea ice extension i...
Published in: | Global and Planetary Change |
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Elsevier
2020
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Online Access: | https://oceanrep.geomar.de/id/eprint/48416/ https://oceanrep.geomar.de/id/eprint/48416/1/Karas%20et%20al.,%202019.pdf https://oceanrep.geomar.de/id/eprint/48416/7/Karas_ms.pdf https://doi.org/10.1016/j.gloplacha.2019.103085 |
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ftoceanrep:oai:oceanrep.geomar.de:48416 2023-05-15T14:55:37+02:00 Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, B. D. A. Nürnberg, Dirk Herrle, Jens O. 2020-01 text https://oceanrep.geomar.de/id/eprint/48416/ https://oceanrep.geomar.de/id/eprint/48416/1/Karas%20et%20al.,%202019.pdf https://oceanrep.geomar.de/id/eprint/48416/7/Karas_ms.pdf https://doi.org/10.1016/j.gloplacha.2019.103085 en eng Elsevier https://oceanrep.geomar.de/id/eprint/48416/1/Karas%20et%20al.,%202019.pdf https://oceanrep.geomar.de/id/eprint/48416/7/Karas_ms.pdf Karas, C., Khélifi, N., Bahr, A., Naafs, B. D. A., Nürnberg, D. and Herrle, J. O. (2020) Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth?. Open Access Global and Planetary Change, 185 (Article number 103085). DOI 10.1016/j.gloplacha.2019.103085 <https://doi.org/10.1016/j.gloplacha.2019.103085>. doi:10.1016/j.gloplacha.2019.103085 info:eu-repo/semantics/openAccess Article PeerReviewed 2020 ftoceanrep https://doi.org/10.1016/j.gloplacha.2019.103085 2023-04-07T15:48:25Z Highlights • Prominent North Atlantic sea surface cooling and freshening of ~3.5 °C and ~0.7‰ during ~3.65–3.5 Ma. • Surface cooling and freshening inline with a decrease of benthic δ13C records from South Atlantic Ocean sites. • Surface cooling and freshening at the same time as sea ice extension in the Arctic Ocean. Abstract The North Atlantic Current (NAC) as part of the Atlantic Meridional Overturning Circulation (AMOC) is the major supplier of heat into the northern North Atlantic. Pliocene changes of AMOC strength were speculated to either have amplified or diminished the Northern Hemisphere Glaciation (NHG) 2.7 million years ago (Ma). However, from the North Atlantic, little evidence is known about AMOC changes at around 3.6 Ma. At this time the intensification of NHG started and culminated in the first major glacial M2 event at 3.3 Ma. To elaborate the climatic effects of variations in the NAC during this early stage of NHG, we here present millennial-scale resolved records from Deep Sea Drilling (DSDP) Site 610A in the northern North Atlantic. Our data of planktic foraminiferal Mg/Ca-based sea surface temperatures (SSTMg/Ca) and ice volume corrected salinity approximations (δ18OIVC-seawater) span the critical time period 4–3.3 Ma. From 3.65 to 3.5 Ma, we observe a distinct ~3.5 °C cooling and ~0.7‰ freshening of the sea surface, which we interpret to reflect a weakened NAC. At the same time Arctic sea ice grew and benthic δ13C in the South Atlantic suggest a weakened AMOC. We conclude that the weakened NAC in response to a sluggish AMOC fostered sea ice formation in the Arctic Ocean and high-latitude North Atlantic, which might have preconditioned the climate for subsequent continental glaciations. Article in Journal/Newspaper Arctic Arctic Ocean Foraminifera* Ice Sheet north atlantic current North Atlantic Sea ice South Atlantic Ocean OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Arctic Arctic Ocean Global and Planetary Change 185 103085 |
institution |
Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
Highlights • Prominent North Atlantic sea surface cooling and freshening of ~3.5 °C and ~0.7‰ during ~3.65–3.5 Ma. • Surface cooling and freshening inline with a decrease of benthic δ13C records from South Atlantic Ocean sites. • Surface cooling and freshening at the same time as sea ice extension in the Arctic Ocean. Abstract The North Atlantic Current (NAC) as part of the Atlantic Meridional Overturning Circulation (AMOC) is the major supplier of heat into the northern North Atlantic. Pliocene changes of AMOC strength were speculated to either have amplified or diminished the Northern Hemisphere Glaciation (NHG) 2.7 million years ago (Ma). However, from the North Atlantic, little evidence is known about AMOC changes at around 3.6 Ma. At this time the intensification of NHG started and culminated in the first major glacial M2 event at 3.3 Ma. To elaborate the climatic effects of variations in the NAC during this early stage of NHG, we here present millennial-scale resolved records from Deep Sea Drilling (DSDP) Site 610A in the northern North Atlantic. Our data of planktic foraminiferal Mg/Ca-based sea surface temperatures (SSTMg/Ca) and ice volume corrected salinity approximations (δ18OIVC-seawater) span the critical time period 4–3.3 Ma. From 3.65 to 3.5 Ma, we observe a distinct ~3.5 °C cooling and ~0.7‰ freshening of the sea surface, which we interpret to reflect a weakened NAC. At the same time Arctic sea ice grew and benthic δ13C in the South Atlantic suggest a weakened AMOC. We conclude that the weakened NAC in response to a sluggish AMOC fostered sea ice formation in the Arctic Ocean and high-latitude North Atlantic, which might have preconditioned the climate for subsequent continental glaciations. |
format |
Article in Journal/Newspaper |
author |
Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, B. D. A. Nürnberg, Dirk Herrle, Jens O. |
spellingShingle |
Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, B. D. A. Nürnberg, Dirk Herrle, Jens O. Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
author_facet |
Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, B. D. A. Nürnberg, Dirk Herrle, Jens O. |
author_sort |
Karas, Cyrus |
title |
Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
title_short |
Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
title_full |
Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
title_fullStr |
Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
title_full_unstemmed |
Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
title_sort |
did north atlantic cooling and freshening from 3.65–3.5 ma precondition northern hemisphere ice sheet growth? |
publisher |
Elsevier |
publishDate |
2020 |
url |
https://oceanrep.geomar.de/id/eprint/48416/ https://oceanrep.geomar.de/id/eprint/48416/1/Karas%20et%20al.,%202019.pdf https://oceanrep.geomar.de/id/eprint/48416/7/Karas_ms.pdf https://doi.org/10.1016/j.gloplacha.2019.103085 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Foraminifera* Ice Sheet north atlantic current North Atlantic Sea ice South Atlantic Ocean |
genre_facet |
Arctic Arctic Ocean Foraminifera* Ice Sheet north atlantic current North Atlantic Sea ice South Atlantic Ocean |
op_relation |
https://oceanrep.geomar.de/id/eprint/48416/1/Karas%20et%20al.,%202019.pdf https://oceanrep.geomar.de/id/eprint/48416/7/Karas_ms.pdf Karas, C., Khélifi, N., Bahr, A., Naafs, B. D. A., Nürnberg, D. and Herrle, J. O. (2020) Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth?. Open Access Global and Planetary Change, 185 (Article number 103085). DOI 10.1016/j.gloplacha.2019.103085 <https://doi.org/10.1016/j.gloplacha.2019.103085>. doi:10.1016/j.gloplacha.2019.103085 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1016/j.gloplacha.2019.103085 |
container_title |
Global and Planetary Change |
container_volume |
185 |
container_start_page |
103085 |
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1766327646812110848 |