Sensitivity of ocean circulation to warming during the Early Eocene greenhouse
Multiple abrupt warming events (“hyperthermals”) punctuated the Early Eocene and were associated with deep-sea temperature increases of 2 to 4 °C, seafloor carbonate dissolution, and negative carbon isotope (δ 13 C) excursions. Whether hyperthermals were associated with changes in the global ocean o...
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ftopenunivgb:oai:oro.open.ac.uk:97956 2024-06-23T07:55:04+00:00 Sensitivity of ocean circulation to warming during the Early Eocene greenhouse Kirtland Turner, Sandra Ridgwell, Andy Keller, Allison L. Vahlenkamp, Maximilian Aleksinski, Adam K. Sexton, Philip F. Penman, Donald E. Hull, Pincelli M. Norris, Richard D. 2024 application/pdf https://oro.open.ac.uk/97956/ https://oro.open.ac.uk/97956/1/Kirtland-Turner%20etal%202024.pdf en eng https://oro.open.ac.uk/97956/1/Kirtland-Turner%20etal%202024.pdf Kirtland Turner, Sandra; Ridgwell, Andy; Keller, Allison L.; Vahlenkamp, Maximilian; Aleksinski, Adam K.; Sexton, Philip F. <https://oro.open.ac.uk/view/person/pfs67.html>; Penman, Donald E.; Hull, Pincelli M. and Norris, Richard D. (2024). Sensitivity of ocean circulation to warming during the Early Eocene greenhouse. Proceedings of the National Academy of Sciences of the United States of America, 121(24), article no. e2311980121. cc_by_4 Journal Item PeerReviewed 2024 ftopenunivgb 2024-06-12T14:24:53Z Multiple abrupt warming events (“hyperthermals”) punctuated the Early Eocene and were associated with deep-sea temperature increases of 2 to 4 °C, seafloor carbonate dissolution, and negative carbon isotope (δ 13 C) excursions. Whether hyperthermals were associated with changes in the global ocean overturning circulation is important for understanding their driving mechanisms and feedbacks and for gaining insight into the circulation’s sensitivity to climatic warming. Here, we present high-resolution benthic foraminiferal stable isotope records (δ 13 C and δ 18 O) throughout the Early Eocene Climate Optimum (~53.26 to 49.14 Ma) from the deep equatorial and North Atlantic. Combined with existing records from the South Atlantic and Pacific, these indicate consistently amplified δ 13 C excursion sizes during hyperthermals in the deep equatorial Atlantic. We compare these observations with results from an intermediate complexity Earth system model to demonstrate that this spatial pattern of δ 13 C excursion size is a predictable consequence of global warming-induced changes in ocean overturning circulation. In our model, transient warming drives the weakening of Southern Ocean-sourced overturning circulation, strengthens Atlantic meridional water mass aging gradients, and amplifies the magnitude of negative δ 13 C excursions in the equatorial to North Atlantic. Based on model-data consistency, we conclude that Eocene hyperthermals coincided with repeated weakening of the global overturning circulation. Not accounting for ocean circulation impacts on δ 13 C excursions will lead to incorrect estimates of the magnitude of carbon release driving hyperthermals. Our finding of weakening overturning in response to past transient climatic warming is consistent with predictions of declining Atlantic Ocean overturning strength in our warm future. Article in Journal/Newspaper North Atlantic Southern Ocean The Open University: Open Research Online (ORO) Southern Ocean Pacific |
institution |
Open Polar |
collection |
The Open University: Open Research Online (ORO) |
op_collection_id |
ftopenunivgb |
language |
English |
description |
Multiple abrupt warming events (“hyperthermals”) punctuated the Early Eocene and were associated with deep-sea temperature increases of 2 to 4 °C, seafloor carbonate dissolution, and negative carbon isotope (δ 13 C) excursions. Whether hyperthermals were associated with changes in the global ocean overturning circulation is important for understanding their driving mechanisms and feedbacks and for gaining insight into the circulation’s sensitivity to climatic warming. Here, we present high-resolution benthic foraminiferal stable isotope records (δ 13 C and δ 18 O) throughout the Early Eocene Climate Optimum (~53.26 to 49.14 Ma) from the deep equatorial and North Atlantic. Combined with existing records from the South Atlantic and Pacific, these indicate consistently amplified δ 13 C excursion sizes during hyperthermals in the deep equatorial Atlantic. We compare these observations with results from an intermediate complexity Earth system model to demonstrate that this spatial pattern of δ 13 C excursion size is a predictable consequence of global warming-induced changes in ocean overturning circulation. In our model, transient warming drives the weakening of Southern Ocean-sourced overturning circulation, strengthens Atlantic meridional water mass aging gradients, and amplifies the magnitude of negative δ 13 C excursions in the equatorial to North Atlantic. Based on model-data consistency, we conclude that Eocene hyperthermals coincided with repeated weakening of the global overturning circulation. Not accounting for ocean circulation impacts on δ 13 C excursions will lead to incorrect estimates of the magnitude of carbon release driving hyperthermals. Our finding of weakening overturning in response to past transient climatic warming is consistent with predictions of declining Atlantic Ocean overturning strength in our warm future. |
format |
Article in Journal/Newspaper |
author |
Kirtland Turner, Sandra Ridgwell, Andy Keller, Allison L. Vahlenkamp, Maximilian Aleksinski, Adam K. Sexton, Philip F. Penman, Donald E. Hull, Pincelli M. Norris, Richard D. |
spellingShingle |
Kirtland Turner, Sandra Ridgwell, Andy Keller, Allison L. Vahlenkamp, Maximilian Aleksinski, Adam K. Sexton, Philip F. Penman, Donald E. Hull, Pincelli M. Norris, Richard D. Sensitivity of ocean circulation to warming during the Early Eocene greenhouse |
author_facet |
Kirtland Turner, Sandra Ridgwell, Andy Keller, Allison L. Vahlenkamp, Maximilian Aleksinski, Adam K. Sexton, Philip F. Penman, Donald E. Hull, Pincelli M. Norris, Richard D. |
author_sort |
Kirtland Turner, Sandra |
title |
Sensitivity of ocean circulation to warming during the Early Eocene greenhouse |
title_short |
Sensitivity of ocean circulation to warming during the Early Eocene greenhouse |
title_full |
Sensitivity of ocean circulation to warming during the Early Eocene greenhouse |
title_fullStr |
Sensitivity of ocean circulation to warming during the Early Eocene greenhouse |
title_full_unstemmed |
Sensitivity of ocean circulation to warming during the Early Eocene greenhouse |
title_sort |
sensitivity of ocean circulation to warming during the early eocene greenhouse |
publishDate |
2024 |
url |
https://oro.open.ac.uk/97956/ https://oro.open.ac.uk/97956/1/Kirtland-Turner%20etal%202024.pdf |
geographic |
Southern Ocean Pacific |
geographic_facet |
Southern Ocean Pacific |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_relation |
https://oro.open.ac.uk/97956/1/Kirtland-Turner%20etal%202024.pdf Kirtland Turner, Sandra; Ridgwell, Andy; Keller, Allison L.; Vahlenkamp, Maximilian; Aleksinski, Adam K.; Sexton, Philip F. <https://oro.open.ac.uk/view/person/pfs67.html>; Penman, Donald E.; Hull, Pincelli M. and Norris, Richard D. (2024). Sensitivity of ocean circulation to warming during the Early Eocene greenhouse. Proceedings of the National Academy of Sciences of the United States of America, 121(24), article no. e2311980121. |
op_rights |
cc_by_4 |
_version_ |
1802647462328926208 |