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Millennial-scale trends in west Pacific warm pool hydrology since the Last Glacial Maximum


Stalagmite close-up.  Photo by Jud Partin. Millennial-scale trends in west Pacific warm pool hydrology since the Last Glacial Maximum

Nature
Vol. 449, No. 7161, pp. 452-455, 27 September 2007, doi:10.1038/nature06164.

Judson W. Partin1, Kim M. Cobb1, Jess F. Adkins2, Brian Clark3 & Diego P. Fernandez2

1 School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

2 Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA

3 Gunung Mulu National Park, Sarawak, Malaysia
ABSTRACT:
Models and palaeoclimate data suggest that the tropical Pacific climate system plays a key part in the mechanisms underlying orbital-scale and abrupt climate change. Atmospheric convection over the western tropical Pacific is a major source of heat and moisture to extratropical regions, and may therefore influence the global climate response to a variety of forcing factors. The response of tropical Pacific convection to changes in global climate boundary conditions, abrupt climate changes and radiative forcing remains uncertain, however. Here we present three absolutely-dated oxygen isotope records from stalagmites in northern Borneo that reflect changes in west Pacific warm pool hydrology over the past 27,000 years. Our results suggest that convection over the western tropical Pacific weakened 18,000-20,000 years ago, as tropical Pacific and Antarctic temperatures began to rise during the early stages of deglaciation. Convective activity, as inferred from oxygen isotopes, reached a minimum during Heinrich event 1, when the Atlantic meridional overturning circulation was weak, pointing to feedbacks between the strength of the overturning circulation and tropical Pacific hydrology. There is no evidence of the Younger Dryas event in the stalagmite records, however, suggesting that different mechanisms operated during these two abrupt deglacial climate events. During the Holocene epoch, convective activity appears to track changes in spring and autumn insolation, highlighting the sensitivity of tropical Pacific convection to external radiative forcing. Together, these findings demonstrate that the tropical Pacific hydrological cycle is sensitive to high-latitude climate processes in both hemispheres, as well as to external radiative forcing, and that it may have a central role in abrupt climate change events.
Download data from the WDC Paleo archive:
Stalagmite δ18O data from Snail Shell Cave and Bukit Assam Cave, Gunung Buda National Park, Northern Borneo, Malaysia, Text or Excel format.

To read or view the full study, please visit the Nature website.
It was published in Nature, Vol. 449, No. 7161, pp. 452-455, 27 September 2007, doi:10.1038/nature06164.
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