Disconnection of the late Pliocene Agulhas Leakage from Atlantic Meridional Overturning Circulation

Abstract The strength of the Atlantic Meridional Overturning Circulation (AMOC), in terms of streamfunction, is considered to depend partly on salt supply from the Indian Ocean through Agulhas Leakage (AL). In turn, AL is regulated by the position of the Southern Ocean subtropical front, which creates the pathway of the leaking around the African continent. Here, to evaluate the links between the subtropical front, AL and AMOC, we present latitudinal shifts of the subtropical front, and thereby potential AL changes, using dinoflagellate cysts and biomarkers in sediment cores from the Agulhas Plateau covering the late Pliocene (3,600–2,580 thousand years ago (ka)). We subsequently compare our frontal migration and AL reconstruction with ocean surface and bottom records along the AMOC pathway, and climate model simulations, to evaluate the influence of the AL on the AMOC. We find that the northward migration of the subtropical front gradually reduced the volume and salt supply of AL from 3,600 ka to 3,300 ka, whereas the AMOC intensified. We conclude that the causal link between the AL and AMOC was disconnected during the late Pliocene, challenging the presumed role of the AL in modulating the AMOC.

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Journal
Nature Geoscience
Published
2026-08-03
DOI
https://doi.org/10.1038/s41561-026-02055-5
Primary Topic
Geology and Paleoclimatology Research
Type
article
Field-Weighted Citation Impact
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article

Disconnection of the late Pliocene Agulhas Leakage from Atlantic Meridional Overturning Circulation

Francesca Sangiorgi, Malte Stockhausen, Suning Hou, Melissa A. Berke et al.
Nature Geoscience
Geology and Paleoclimatology Research
article

Disconnection of the late Pliocene Agulhas Leakage from Atlantic Meridional Overturning Circulation

Francesca Sangiorgi, Malte Stockhausen, Suning Hou, Melissa A. Berke, Peter K. Bijl, Appy Sluijs, Ning Tan, Aidan Starr, Isla S. Castañeda, Fenghao Liu, Anna S. von der Heydt, Francien Peterse, Alejandra Cartagena-Sierra, Carolien M. H. van der Weijst
article en

Abstract

Abstract The strength of the Atlantic Meridional Overturning Circulation (AMOC), in terms of streamfunction, is considered to depend partly on salt supply from the Indian Ocean through Agulhas Leakage (AL). In turn, AL is regulated by the position of the Southern Ocean subtropical front, which creates the pathway of the leaking around the African continent. Here, to evaluate the links between the subtropical front, AL and AMOC, we present latitudinal shifts of the subtropical front, and thereby potential AL changes, using dinoflagellate cysts and biomarkers in sediment cores from the Agulhas Plateau covering the late Pliocene (3,600–2,580 thousand years ago (ka)). We subsequently compare our frontal migration and AL reconstruction with ocean surface and bottom records along the AMOC pathway, and climate model simulations, to evaluate the influence of the AL on the AMOC. We find that the northward migration of the subtropical front gradually reduced the volume and salt supply of AL from 3,600 ka to 3,300 ka, whereas the AMOC intensified. We conclude that the causal link between the AL and AMOC was disconnected during the late Pliocene, challenging the presumed role of the AL in modulating the AMOC.

Nature Geoscience
University of Notre Dame (US), Tongji University (CN), Utrecht University (NL), Chinese Academy of Sciences (CN), University of Cambridge (GB), University of Massachusetts Amherst (US), Institute of Geology and Geophysics (CN)
National Science Foundation, National Natural Science Foundation of China, Chinese Academy of Sciences, Netherlands Earth System Science Centre, National Oceanic and Atmospheric Administration, Horizon 2020 Framework Programme, NOAA Pacific Marine Environmental Laboratory
Life below water
Openalex Percentile: Top 13%
Geology and Paleoclimatology Research
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