Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth?
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 mil...
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ftunivchile:oai:repositorio.uchile.cl:2250/174699 2023-06-18T03:39:21+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, Bernhard Nürnberg, Dirk Herrle, Jens O. 2020 application/pdf https://doi.org/10.1016/j.gloplacha.2019.103085 https://repositorio.uchile.cl/handle/2250/174699 en eng Elsevier Global and Planetary Change 185 (2020) 103085 doi:10.1016/j.gloplacha.2019.103085 https://repositorio.uchile.cl/handle/2250/174699 Attribution-NonCommercial-NoDerivs 3.0 Chile http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ Global and Planetary Change Pliocene Northern Hemisphere Glaciation NAC AMOC Foraminiferal Mg/Ca Artículo de revista 2020 ftunivchile https://doi.org/10.1016/j.gloplacha.2019.103085 2023-06-03T23:51:53Z 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 (delta O-18(IV)C-seawater) span the critical time period 4-3.3 Ma. From 3.65 to 3.5 Ma, we observe a distinct similar to 3.5 degrees C cooling and similar to 0.7 parts per thousand freshening of the sea surface, which we interpret to reflect a weakened NAC. At the same time Arctic sea ice grew and benthic delta C-13 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. German Research Foundation (DFG) KA3461/1-2 Royal Society of London Tata Group Article in Journal/Newspaper Arctic Arctic Ocean Foraminifera* Ice Sheet north atlantic current North Atlantic Sea ice Universidad de Chile: Repositorio académico Arctic Arctic Ocean Global and Planetary Change 185 103085 |
institution |
Open Polar |
collection |
Universidad de Chile: Repositorio académico |
op_collection_id |
ftunivchile |
language |
English |
topic |
Pliocene Northern Hemisphere Glaciation NAC AMOC Foraminiferal Mg/Ca |
spellingShingle |
Pliocene Northern Hemisphere Glaciation NAC AMOC Foraminiferal Mg/Ca Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, Bernhard Nürnberg, Dirk Herrle, Jens O. Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? |
topic_facet |
Pliocene Northern Hemisphere Glaciation NAC AMOC Foraminiferal Mg/Ca |
description |
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 (delta O-18(IV)C-seawater) span the critical time period 4-3.3 Ma. From 3.65 to 3.5 Ma, we observe a distinct similar to 3.5 degrees C cooling and similar to 0.7 parts per thousand freshening of the sea surface, which we interpret to reflect a weakened NAC. At the same time Arctic sea ice grew and benthic delta C-13 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. German Research Foundation (DFG) KA3461/1-2 Royal Society of London Tata Group |
format |
Article in Journal/Newspaper |
author |
Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, Bernhard Nürnberg, Dirk Herrle, Jens O. |
author_facet |
Karas, Cyrus Khélifi, Nabil Bahr, André Naafs, Bernhard 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://doi.org/10.1016/j.gloplacha.2019.103085 https://repositorio.uchile.cl/handle/2250/174699 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Foraminifera* Ice Sheet north atlantic current North Atlantic Sea ice |
genre_facet |
Arctic Arctic Ocean Foraminifera* Ice Sheet north atlantic current North Atlantic Sea ice |
op_source |
Global and Planetary Change |
op_relation |
Global and Planetary Change 185 (2020) 103085 doi:10.1016/j.gloplacha.2019.103085 https://repositorio.uchile.cl/handle/2250/174699 |
op_rights |
Attribution-NonCommercial-NoDerivs 3.0 Chile http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ |
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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1769004109972635648 |