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Current Atlantic Meridional Overturning Circulation weakest in last millennium

Abstract

The Atlantic Meridional Overturning Circulation (AMOC)—one of Earth’s major ocean circulation systems—redistributes heat on our planet and has a major impact on climate. Here, we compare a variety of published proxy records to reconstruct the evolution of the AMOC since about ad 400. A fairly consistent picture of the AMOC emerges: after a long and relatively stable period, there was an initial weakening starting in the nineteenth century, followed by a second, more rapid, decline in the mid-twentieth century, leading to the weakest state of the AMOC occurring in recent decades.

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Fig. 1: SST-based AMOC reconstructions compared with various proxy reconstructions.

Data availability

The proxy datasets that are analysed in this study are available in a GitHub repository: https://github.com/ncahill89/AMOC-Analysis.

Code availability

The scripts for the change point and the significance testing are available in a GitHub repository: https://github.com/ncahill89/AMOC-Analysis.

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Acknowledgements

L.C., N.C. and G.D.McC. are supported by the A4 project. A4 (Grant-Aid Agreement no. PBA/CC/18/01) is carried out with the support of the Marine Institute under the Marine Research Programme funded by the Irish Government, co-financed by the European Regional Development Fund. D.J.R.T. is supported by UK NERC grant NE/S009736/1.

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S.R. initiated the study. L.C. created the figure and wrote the manuscript. N.C. performed the significance testing. All authors discussed and interpreted the results and provided input to the manuscript.

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Correspondence to L. Caesar.

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The authors declare no competing interests.

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Peer review information Nature Geoscience thanks the anonymous reviewers for their contribution to the peer review of this work. Primary Handling Editor: James Super.

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Caesar, L., McCarthy, G.D., Thornalley, D.J.R. et al. Current Atlantic Meridional Overturning Circulation weakest in last millennium. Nat. Geosci. 14, 118–120 (2021). https://doi.org/10.1038/s41561-021-00699-z

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