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...
Published in: | Climate of the Past |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2021
|
Subjects: | |
Online Access: | https://doi.org/10.5194/cp-17-2255-2021 https://cp.copernicus.org/articles/17/2255/2021/cp-17-2255-2021.pdf https://doaj.org/article/2922e7c628d14838a1e8c53180e96ffc |
id |
fttriple:oai:gotriple.eu:oai:doaj.org/article:2922e7c628d14838a1e8c53180e96ffc |
---|---|
record_format |
openpolar |
spelling |
fttriple:oai:gotriple.eu:oai:doaj.org/article:2922e7c628d14838a1e8c53180e96ffc 2023-05-15T16:41:12+02:00 Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition T. J. Leutert S. Modestou S. M. Bernasconi A. N. Meckler 2021-10-01 https://doi.org/10.5194/cp-17-2255-2021 https://cp.copernicus.org/articles/17/2255/2021/cp-17-2255-2021.pdf https://doaj.org/article/2922e7c628d14838a1e8c53180e96ffc en eng Copernicus Publications doi:10.5194/cp-17-2255-2021 1814-9324 1814-9332 https://cp.copernicus.org/articles/17/2255/2021/cp-17-2255-2021.pdf https://doaj.org/article/2922e7c628d14838a1e8c53180e96ffc undefined Climate of the Past, Vol 17, Pp 2255-2271 (2021) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2021 fttriple https://doi.org/10.5194/cp-17-2255-2021 2023-01-22T17:53:24Z 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. Article in Journal/Newspaper Ice Sheet Southern Ocean Unknown Southern Ocean Climate of the Past 17 5 2255 2271 |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
fttriple |
language |
English |
topic |
geo envir |
spellingShingle |
geo envir T. J. Leutert S. Modestou S. M. Bernasconi A. N. Meckler Southern Ocean bottom-water cooling and ice sheet expansion during the middle Miocene climate transition |
topic_facet |
geo envir |
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. |
format |
Article in Journal/Newspaper |
author |
T. J. Leutert S. Modestou S. M. Bernasconi A. N. Meckler |
author_facet |
T. J. Leutert S. Modestou S. M. Bernasconi A. N. Meckler |
author_sort |
T. J. Leutert |
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://doi.org/10.5194/cp-17-2255-2021 https://cp.copernicus.org/articles/17/2255/2021/cp-17-2255-2021.pdf https://doaj.org/article/2922e7c628d14838a1e8c53180e96ffc |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Ice Sheet Southern Ocean |
genre_facet |
Ice Sheet Southern Ocean |
op_source |
Climate of the Past, Vol 17, Pp 2255-2271 (2021) |
op_relation |
doi:10.5194/cp-17-2255-2021 1814-9324 1814-9332 https://cp.copernicus.org/articles/17/2255/2021/cp-17-2255-2021.pdf https://doaj.org/article/2922e7c628d14838a1e8c53180e96ffc |
op_rights |
undefined |
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_ |
1766031630958329856 |