Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition
The middle Miocene climate transition (MMCT), around 14 Ma, was associated with a significant climatic shift, but the mechanisms triggering the event remain enigmatic. We present a clumped isotope (Δ47) bottom-water temperature (BWT) record from 16.0 to 12.2 Ma from Ocean Drilling Program (ODP) Site...
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ftunivbergen:oai:bora.uib.no:11250/2989606 2023-05-15T16:41:10+02:00 Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition Leutert, Thomas Jan Modestou, Sevasti Eleni Bernasconi, Stefano M. Meckler, A. Nele 2021 application/pdf https://hdl.handle.net/11250/2989606 https://doi.org/10.5194/cp-17-2255-2021 eng eng Copernicus Publications ERC-European Research Council: 638467 Norges forskningsråd: 245907 urn:issn:1814-9324 https://hdl.handle.net/11250/2989606 https://doi.org/10.5194/cp-17-2255-2021 cristin:1954881 Climate of the Past. 2021, 17 (5), 2255-2271. Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright Author(s) 2021 Climate of the Past 2255-2271 17 5 Journal article Peer reviewed 2021 ftunivbergen https://doi.org/10.5194/cp-17-2255-2021 2023-03-14T17:43:13Z The middle Miocene climate transition (MMCT), around 14 Ma, was associated with a significant climatic shift, but the mechanisms triggering the event remain enigmatic. We present a clumped isotope (Δ47) bottom-water temperature (BWT) record from 16.0 to 12.2 Ma from Ocean Drilling Program (ODP) Site 747 in the Southern Ocean and compare it to existing BWT records from different latitudes. We show that BWTs in the Southern Ocean reached 8–10 ∘C during the Miocene climatic optimum. These high BWT values indicate considerably warmer bottom-water conditions than today. Nonetheless, bottom-water δ18O (calculated from foraminiferal δ18O and Δ47) suggests substantial amounts of land ice throughout the interval of the study. Our dataset further demonstrates that BWTs at Site 747 were variable with an overall cooling trend across the MMCT. Notably, a cooling of around 3–5 ∘C preceded the stepped main increase in benthic δ18O, interpreted as global ice volume expansion, and appears to have been followed by a transient bottom-water warming starting during or slightly after the main ice volume increase. We speculate that a regional freshening of the upper water column at this time may have increased stratification and reduced bottom-water heat loss to the atmosphere, counteracting global cooling in the bottom waters of the Southern Ocean and possibly even at larger scales. Feedbacks required for substantial ice growth and/or tectonic processes may have contributed to the observed decoupling of global ice volume and Southern Ocean BWT. publishedVersion Article in Journal/Newspaper Ice Sheet Southern Ocean University of Bergen: Bergen Open Research Archive (BORA-UiB) Southern Ocean Climate of the Past 17 5 2255 2271 |
institution |
Open Polar |
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University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
description |
The middle Miocene climate transition (MMCT), around 14 Ma, was associated with a significant climatic shift, but the mechanisms triggering the event remain enigmatic. We present a clumped isotope (Δ47) bottom-water temperature (BWT) record from 16.0 to 12.2 Ma from Ocean Drilling Program (ODP) Site 747 in the Southern Ocean and compare it to existing BWT records from different latitudes. We show that BWTs in the Southern Ocean reached 8–10 ∘C during the Miocene climatic optimum. These high BWT values indicate considerably warmer bottom-water conditions than today. Nonetheless, bottom-water δ18O (calculated from foraminiferal δ18O and Δ47) suggests substantial amounts of land ice throughout the interval of the study. Our dataset further demonstrates that BWTs at Site 747 were variable with an overall cooling trend across the MMCT. Notably, a cooling of around 3–5 ∘C preceded the stepped main increase in benthic δ18O, interpreted as global ice volume expansion, and appears to have been followed by a transient bottom-water warming starting during or slightly after the main ice volume increase. We speculate that a regional freshening of the upper water column at this time may have increased stratification and reduced bottom-water heat loss to the atmosphere, counteracting global cooling in the bottom waters of the Southern Ocean and possibly even at larger scales. Feedbacks required for substantial ice growth and/or tectonic processes may have contributed to the observed decoupling of global ice volume and Southern Ocean BWT. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Leutert, Thomas Jan Modestou, Sevasti Eleni Bernasconi, Stefano M. Meckler, A. Nele |
spellingShingle |
Leutert, Thomas Jan Modestou, Sevasti Eleni Bernasconi, Stefano M. Meckler, A. Nele Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
author_facet |
Leutert, Thomas Jan Modestou, Sevasti Eleni Bernasconi, Stefano M. Meckler, A. Nele |
author_sort |
Leutert, Thomas Jan |
title |
Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
title_short |
Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
title_full |
Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
title_fullStr |
Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
title_full_unstemmed |
Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
title_sort |
southern ocean bottom-water cooling and ice sheet expansion during the middle miocene climate transition |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://hdl.handle.net/11250/2989606 https://doi.org/10.5194/cp-17-2255-2021 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Ice Sheet Southern Ocean |
genre_facet |
Ice Sheet Southern Ocean |
op_source |
Climate of the Past 2255-2271 17 5 |
op_relation |
ERC-European Research Council: 638467 Norges forskningsråd: 245907 urn:issn:1814-9324 https://hdl.handle.net/11250/2989606 https://doi.org/10.5194/cp-17-2255-2021 cristin:1954881 Climate of the Past. 2021, 17 (5), 2255-2271. |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright Author(s) 2021 |
op_doi |
https://doi.org/10.5194/cp-17-2255-2021 |
container_title |
Climate of the Past |
container_volume |
17 |
container_issue |
5 |
container_start_page |
2255 |
op_container_end_page |
2271 |
_version_ |
1766031606300016640 |