Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years

The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth’s climate, redistributing heat and influencing the carbon cycle1, 2. The AMOC has been shown to be weakening in recent years1; this decline may reflect decadal-scale variability i...

Full description

Bibliographic Details
Published in:Nature
Main Authors: Thornalley, David J. R., Oppo, Delia W., Ortega, Pablo, Robson, Jon I., Brierley, Chris M., Davis, Renee, Hall, Ian R., Moffa-Sanchez, Paola, Rose, Neil L., Spooner, Peter T., Yashayaev, Igor, Keigwin, Lloyd D.
Format: Article in Journal/Newspaper
Language:English
Published: Nature 2018
Subjects:
Online Access:https://orca.cardiff.ac.uk/id/eprint/110650/
https://doi.org/10.1038/s41586-018-0007-4
https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf
id ftunivcardiff:oai:https://orca.cardiff.ac.uk:110650
record_format openpolar
spelling ftunivcardiff:oai:https://orca.cardiff.ac.uk:110650 2023-05-15T15:13:12+02:00 Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years Thornalley, David J. R. Oppo, Delia W. Ortega, Pablo Robson, Jon I. Brierley, Chris M. Davis, Renee Hall, Ian R. Moffa-Sanchez, Paola Rose, Neil L. Spooner, Peter T. Yashayaev, Igor Keigwin, Lloyd D. 2018-04-30 application/pdf https://orca.cardiff.ac.uk/id/eprint/110650/ https://doi.org/10.1038/s41586-018-0007-4 https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf en eng Nature https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf Thornalley, David J. R., Oppo, Delia W., Ortega, Pablo, Robson, Jon I., Brierley, Chris M., Davis, Renee, Hall, Ian R. https://orca.cardiff.ac.uk/view/cardiffauthors/A002402L.html orcid:0000-0001-6960-1419 orcid:0000-0001-6960-1419, Moffa-Sanchez, Paola https://orca.cardiff.ac.uk/view/cardiffauthors/A2264630T.html, Rose, Neil L., Spooner, Peter T., Yashayaev, Igor and Keigwin, Lloyd D. 2018. Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Nature 556 (7700) , pp. 227-230. 10.1038/s41586-018-0007-4 https://doi.org/10.1038/s41586-018-0007-4 file https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf doi:10.1038/s41586-018-0007-4 Article PeerReviewed 2018 ftunivcardiff https://doi.org/10.1038/s41586-018-0007-4 2022-10-27T22:43:52Z The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth’s climate, redistributing heat and influencing the carbon cycle1, 2. The AMOC has been shown to be weakening in recent years1; this decline may reflect decadal-scale variability in convection in the Labrador Sea, but short observational datasets preclude a longer-term perspective on the modern state and variability of Labrador Sea convection and the AMOC1, 3,4,5. Here we provide several lines of palaeo-oceanographic evidence that Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately ad 1850) compared with the preceding 1,500 years. Our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the LIA, or as a more gradual, continued decline over the past 150 years; this ambiguity probably arises from non-AMOC influences on the various proxies or from the different sensitivities of these proxies to individual components of the AMOC. We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA—sourced from melting glaciers and thickened sea ice that developed earlier in the LIA—weakened Labrador Sea convection and the AMOC. The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet6. Our results suggest that recent decadal variability in Labrador Sea convection and the AMOC has occurred during an atypical, weak background state. Future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the AMOC weakening described here. Article in Journal/Newspaper Arctic Greenland Labrador Sea Nordic Seas Sea ice Cardiff University: ORCA (Online Research @ Cardiff) Arctic Greenland Nature 556 7700 227 230
institution Open Polar
collection Cardiff University: ORCA (Online Research @ Cardiff)
op_collection_id ftunivcardiff
language English
description The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth’s climate, redistributing heat and influencing the carbon cycle1, 2. The AMOC has been shown to be weakening in recent years1; this decline may reflect decadal-scale variability in convection in the Labrador Sea, but short observational datasets preclude a longer-term perspective on the modern state and variability of Labrador Sea convection and the AMOC1, 3,4,5. Here we provide several lines of palaeo-oceanographic evidence that Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately ad 1850) compared with the preceding 1,500 years. Our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the LIA, or as a more gradual, continued decline over the past 150 years; this ambiguity probably arises from non-AMOC influences on the various proxies or from the different sensitivities of these proxies to individual components of the AMOC. We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA—sourced from melting glaciers and thickened sea ice that developed earlier in the LIA—weakened Labrador Sea convection and the AMOC. The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet6. Our results suggest that recent decadal variability in Labrador Sea convection and the AMOC has occurred during an atypical, weak background state. Future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the AMOC weakening described here.
format Article in Journal/Newspaper
author Thornalley, David J. R.
Oppo, Delia W.
Ortega, Pablo
Robson, Jon I.
Brierley, Chris M.
Davis, Renee
Hall, Ian R.
Moffa-Sanchez, Paola
Rose, Neil L.
Spooner, Peter T.
Yashayaev, Igor
Keigwin, Lloyd D.
spellingShingle Thornalley, David J. R.
Oppo, Delia W.
Ortega, Pablo
Robson, Jon I.
Brierley, Chris M.
Davis, Renee
Hall, Ian R.
Moffa-Sanchez, Paola
Rose, Neil L.
Spooner, Peter T.
Yashayaev, Igor
Keigwin, Lloyd D.
Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
author_facet Thornalley, David J. R.
Oppo, Delia W.
Ortega, Pablo
Robson, Jon I.
Brierley, Chris M.
Davis, Renee
Hall, Ian R.
Moffa-Sanchez, Paola
Rose, Neil L.
Spooner, Peter T.
Yashayaev, Igor
Keigwin, Lloyd D.
author_sort Thornalley, David J. R.
title Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
title_short Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
title_full Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
title_fullStr Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
title_full_unstemmed Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years
title_sort anomalously weak labrador sea convection and atlantic overturning during the past 150 years
publisher Nature
publishDate 2018
url https://orca.cardiff.ac.uk/id/eprint/110650/
https://doi.org/10.1038/s41586-018-0007-4
https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf
geographic Arctic
Greenland
geographic_facet Arctic
Greenland
genre Arctic
Greenland
Labrador Sea
Nordic Seas
Sea ice
genre_facet Arctic
Greenland
Labrador Sea
Nordic Seas
Sea ice
op_relation https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf
Thornalley, David J. R., Oppo, Delia W., Ortega, Pablo, Robson, Jon I., Brierley, Chris M., Davis, Renee, Hall, Ian R. https://orca.cardiff.ac.uk/view/cardiffauthors/A002402L.html orcid:0000-0001-6960-1419 orcid:0000-0001-6960-1419, Moffa-Sanchez, Paola https://orca.cardiff.ac.uk/view/cardiffauthors/A2264630T.html, Rose, Neil L., Spooner, Peter T., Yashayaev, Igor and Keigwin, Lloyd D. 2018. Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years. Nature 556 (7700) , pp. 227-230. 10.1038/s41586-018-0007-4 https://doi.org/10.1038/s41586-018-0007-4 file https://orca.cardiff.ac.uk/id/eprint/110650/1/Combined_accepted_text_figs_extended.pdf
doi:10.1038/s41586-018-0007-4
op_doi https://doi.org/10.1038/s41586-018-0007-4
container_title Nature
container_volume 556
container_issue 7700
container_start_page 227
op_container_end_page 230
_version_ 1766343793002414080