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Stable sea surface temperatures in the western Pacific warm pool over the past 1.75 million years.
Map of Core location and modern Sea Surface Temperature Stable sea surface temperatures in the western Pacific warm pool over the past 1.75 million years.
Nature, Vol. 433, No.7023, pp. 294 - 298, 20 January 2005.

Thibault de Garidel-Thoron1, Yair Rosenthal1,2, Franck Bassinot3, Luc Beaufort4

1 Institute of Marine and Coastal Sciences-Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA
2Department of Geological Sciences-Rutgers University, New Brunswick, New Jersey 08901, USA
3Laboratoire des Sciences du Climat et de l'Environnement-CEA, 91198 Gif-sur-Yvette cedex, France
4CEREGE-CNRS Université Aix-Marseille 3, BP80, 135345 Aix-en-Provence cedex 4, France
ABSTRACT:
About 850,000 years ago, the period of the glacial cycles changed from 41,000 to 100,000 years. This mid-Pleistocene climate transition has been attributed to global cooling, possibly caused by a decrease in atmospheric carbon dioxide concentrations. However, evidence for such cooling is currently restricted to the cool upwelling regions in the eastern equatorial oceans, although the tropical warm pools on the western side of the ocean basins are particularly sensitive to changes in radiative forcing. Here we present high-resolution records of sea surface temperatures spanning the past 1.75 million years, obtained from oxygen isotopes and Mg/Ca ratios in planktonic foraminifera from the western Pacific warm pool. In contrast with the eastern equatorial regions, sea surface temperatures in the western Pacific warm pool are relatively stable throughout the Pleistocene epoch, implying little long-term change in the tropical net radiation budget. Our results challenge the hypothesis of a gradual decrease in atmospheric carbon dioxide concentrations as a dominant trigger of the longer glacial cycles since 850,000 years ago. Instead, we infer that the temperature contrast across the equatorial Pacific Ocean increased, which might have had a significant influence on the mid-Pleistocene climate transition.

Download data from the WDC Paleo archive:
Western Pacific Warm Pool Pleistocene paired d18O-Mg/Ca and SST Reconstruction


To read or view the full study, please visit the Nature website.
It was published in Nature, Vol. 433, pp. 294 - 298, 20 January 2005.
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27 January 2005