Atlantic circulation changes across a stadial-interstadial transition

Date 2022-10
Author(s) Waelbroeck ClaireORCID1, Tjiputra JerryORCID2, Guo ChunchengORCID2, Nisancioglu Kerim H.ORCID3, Jansen EysteinORCID2, 3, Vazquez Riveiros NataliaORCID4, Toucanne SamuelORCID4, Eynaud FrédériqueORCID5, Rossignol LindaORCID5, Dewilde Fabien6, Marches Elodie7, Lebreiro Susana8, Nave SilviaORCID9
Affiliation(s) 1 : LOCEAN/IPSL, Sorbonne Université-CNRS-IRD-MNHN, UMR7159, 75005 Paris, France
2 : NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, 5007 Bergen, Norway
3 : Department of Earth Science, University of Bergen, Bjerknes Centre for Climate Research, 5007 Bergen, Norway
4 : Geo-Ocean, University of Brest, CNRS, IFREMER, UMR6538, 29280 Plouzané, France
5 : UMR-CNRS 5805 EPOC - OASU, University of Bordeaux, 50023 Pessac, France
6 : IUEM, UMS3113, 29280 Plouzané, France
7 : SHOM, 29228 Brest, France
8 : Instituto Geológico y Minero de España (IGME)-CSIC, 28003 Madrid, Spain
9 : LNEG, I.P., UGHGC, 2610-999 Amadora, Portugal
DOI 10.17882/91130
Publisher SEANOE
Keyword(s) benthic carbon isotopes, stadial-interstadial transition, Heinrich Stadial 4, NorESM climate model, Atlantic meridional overturning circulation

We combine consistently dated benthic carbon isotopic records distributed over the entire Atlantic Ocean with numerical simulations performed by a glacial configuration of the Norwegian Earth System Model with active ocean biogeochemistry, in order to interpret the observed Cibicides δ13C changes at the stadial-interstadial transition corresponding to the end of Heinrich Stadial 4 (HS4) in terms of ocean circulation and remineralization changes. We show that the marked increase in Cibicides δ13C observed at the end of HS4 between ~2000 and 4200 m in the Atlantic can be explained by changes in nutrient concentrations as simulated by the model in response to the halting of freshwater input in the high latitude glacial North Atlantic. Our model results show that this Cibicides δ13C signal is associated with changes in the ratio of southern-sourced (SSW) versus northern-sourced (NSW) water masses at the core sites, whereby SSW is replaced by NSW as a consequence of the resumption of deep water formation in the northern North Atlantic and Nordic Seas after the freshwater input is halted. Our results further suggest that the contribution of ocean circulation changes to this signal increases from ~40% at 2000 m to ~80% at 4000 m. Below ~4200 m, the model shows little ocean circulation change but an increase in remineralization across the HS4-GI8 transition. The simulated lower remineralization during stadials than interstadials is particularly pronounced in deep subantarctic sites, in agreement with the decrease in the export production of carbon to the deep Southern Ocean during stadials found in previous studies.

Licence CC-BY-NC
Acknowledgements The research leading to these results has received funding from the Norwegian Research Council KLIMAFORSK contract 326603/E10 and Coordination and Support Activity contract 310328/E10. It derives from exchanges and collaborations between participants in the ACCLIMATE ERC project (FP7/2007-2013 Grant agreement n° 339108) and ice2ice ERC project (FP7/2007‐2013) Grant agreement no610055). We are indebted to G. Isguder for her micropaleontological expertise and help in sample preparation. We acknowledge N. Smialkowski, L. Mauclair and L. Leroy for processing the samples. We thank the French Paul Emile Victor Institute (IPEV) and the crew of the research vessel Marion‐Dufresne for collecting core MD16-3511Q. We also thank P. Guyomard to having given us access to core CAR2013-PQP-CAR05 in the SHOM core repository. We are grateful to D. Hodell for sharing reflectance data of core DSDP609. CG acknowledges support from the Research Council of Norway funded projects ABRUPT (325222). SL acknowledges funding from project CTM2017-84113-R.
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Waelbroeck Claire, Tjiputra Jerry, Guo Chuncheng, Nisancioglu Kerim H., Jansen Eystein, Vazquez Riveiros Natalia, Toucanne Samuel, Eynaud Frédérique, Rossignol Linda, Dewilde Fabien, Marches Elodie, Lebreiro Susana, Nave Silvia (2022). Atlantic circulation changes across a stadial-interstadial transition. SEANOE.