|
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.
|