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Meridional shifts of the Atlantic intertropical convergence zone since the Last Glacial Maximum

Nature Geoscience volume 6, pages 959–962 (2013)Cite this article

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Abstract

The intertropical convergence zone is a near-equatorial band of intense rainfall and convection. Over the modern Atlantic Ocean, its annual average position1 is approximately 5° N, and it is associated with low sea surface salinity and high surface temperatures. This average position has varied since the Last Glacial Maximum, in response to changing climate boundary conditions2,3,4,5,6,7,8,9,10,11,12,13,14,15. The nature of this variation is less clear, with suggestions that the intertropical convergence zone migrated north–south away from the colder hemisphere10,11,12,13,14,15 or that it contracted and expanded symmetrically around its present position2. Here we use paired Mg/Ca and δ18O measurements of planktonic foraminifera for a transect of ocean sediment cores to reconstruct past changes in tropical surface ocean temperature and salinity in the Atlantic Ocean over the past 25,000 years. We show that the low-salinity, high-temperature surface waters associated with the intertropical convergence zone migrated southward of their present position during the Last Glacial Maximum, when the Northern Hemisphere cooled, and northward during the warmer early Holocene, by about ±7° of latitude. Our evidence suggests that the intertropical convergence zone moved latitudinally over the ocean, rather than expanding or contracting. We conclude that the marine intertropical convergence zone has migrated significantly away from its present position owing to external climate forcing during the past 25,000 years.

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Figure 1: Map of core locations and approximate modern mean annual ITCZ location.
Figure 2: SST and opal records since the LGM.
Figure 3: Palaeohydrological records arranged by location.

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  • 18 October 2013

    In the version of this Article originally published online, there were errors in the author affiliations. This has been corrected in all versions of the Article.

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Acknowledgements

This work was supported by NSF award OCE-0927247 and NOAA award NAO80AR4320912 awarded to P.B.dM. and a NOAA Climate and Global Change Postdoctoral Fellowship awarded to J.A.A. This project was partially supported by the LDEO Climate and Life initiative. We wish to thank R. Anderson, M. Cane, Y. Rosenthal and J. McManus for comments on the manuscript.

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Author notes

  1. Jennifer A. Arbuszewski

    Present address: Present address: Woods Hole Oceanographic Institution, 266Woods Hole Road,Woods Hole, Massachusetts 02543, USA,

  2. Caroline Cléroux

    Present address: Present address: NIOZ Royal Netherlands Institute for Sea Research, Department of Marine Geology, Landsdiep 4, 1797 SZ ’t Horntje (Texel), The Netherlands,

Authors and Affiliations

  1. Lamont-Doherty Earth Observatory of Columbia University,, 61 Route 9W, Palisades, New York 10964, USA

    Jennifer A. Arbuszewski, Peter B. deMenocal & Caroline Cléroux

  2. Department of Environmental Studies, Macalester College, 1600 Grand Avenue, Saint Paul, Minnesota 55105, USA

    Louisa Bradtmiller

  3. College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA

    Alan Mix

Authors
  1. Jennifer A. Arbuszewski
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  2. Peter B. deMenocal
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  3. Caroline Cléroux
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  4. Louisa Bradtmiller
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  5. Alan Mix
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Contributions

J.A.A. collected all data (except where otherwise noted), interpreted results, and prepared the manuscript and figures. P.B.dM. supervised the project, and aided in interpretation, figure making, and editing of the manuscript. C.C. obtained some of the previously unpublished G. ruber isotopic data for core VM30-40, discussed interpretation of results, and contributed to the editing of the manuscript. A.M. and L.B. discussed interpretation of results and contributed to the editing of the manuscript.

Corresponding author

Correspondence to Jennifer A. Arbuszewski.

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The authors declare no competing financial interests.

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Arbuszewski, J., deMenocal, P., Cléroux, C. et al. Meridional shifts of the Atlantic intertropical convergence zone since the Last Glacial Maximum. Nature Geosci 6, 959–962 (2013). https://doi.org/10.1038/ngeo1961

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