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Links between salinity variation in the Caribbean and North Atlantic thermohaline circulation

Modern mean annual salinity in the western tropical Atlantic
Figure SI-1. Modern mean annual salinity in the western tropical Atlantic at 10 m water depth and location of ODP 999A and VM28-122. Note the salinity contrast between the tropical Atlantic and the eastern equatorial Pacific, reflecting regional differences in E vs P.
Links between salinity variation in the Caribbean and North Atlantic thermohaline circulation
Nature
Vol. 428, No. 6979, pp. 160-163, 11 March 2004


Matthew W. Schmidt, Howard J. Spero
Department of Geology, University of California, Davis, California 95616, USA
David W. Lea
Department of Geological Sciences and Marine Science Institute, University of California, Santa Barbara, California 93106, USA

ABSTRACT:
Variations in the strength of the North Atlantic Ocean thermohaline circulation have been linked to rapid climate changes during the last glacial cycle through oscillations in North Atlantic Deep Water formation and northward oceanic heat flux. The strength of the thermohaline circulation depends on the supply of warm, salty water to the North Atlantic, which, after losing heat to the atmosphere, produces the dense water masses that sink to great depths and circulate back south. Here we analyse two Caribbean Sea sediment cores, combining Mg/Ca palaeothermometry with measurements of oxygen isotopes in foraminiferal calcite in order to reconstruct tropical Atlantic surface salinity during the last glacial cycle. We find that Caribbean salinity oscillated between saltier conditions during the cold oxygen isotope stages 2, 4 and 6, and lower salinities during the warm stages 3 and 5, covarying with the strength of North Atlantic Deep Water formation. At the initiation of the Bølling/Allerød warm interval, Caribbean surface salinity decreased abruptly, suggesting that the advection of salty tropical waters into the North Atlantic amplified thermohaline circulation and contributed to high-latitude warming.

DATA:
Download the Caribbean Foraminiferal Mg/Ca, d18OCalcite, and Paleosalinity from the WDC Paleo Archive.
To read or view the full study, please visit the Nature website.
It was published in Nature, Vol. 428, No. 6979, pp. 160-163, 11 March 2004.

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National Oceanic and Atmospheric Administration
16 March 2004