Publication Date:
2022-05-25
Description:
Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 22 (2007): PA4214, doi:10.1029/2007PA001468.
Description:
The tropical Pacific plays a central role in the climate system by providing large diabatic heating that drives the global atmospheric circulation. Quantifying the role of the tropics in late Pleistocene climate change has been hampered by the paucity of paleoclimate records from this region and the lack of realistic transient climate model simulations covering this period. Here we present records of hydrogen isotope ratios (δD) of alkenones from the Panama Basin off the Colombian coast that document hydrologic changes in equatorial South America and the eastern tropical Pacific over the past 27,000 years (a) and the past 3 centuries in detail. Comparison of alkenone δD values with instrumental records of precipitation over the past ∼100 a suggests that δD can be used as a hydrologic proxy. On long timescales our records indicate reduced rainfall during the last glacial period that can be explained by a southward shift of the mean position of the Intertropical Convergence Zone and an associated reduction of Pacific moisture transport into Colombia. Precipitation increases at ∼17 ka in concert with sea surface temperature (SST) cooling in the North Atlantic and the eastern tropical Pacific. A regional coupled model, forced by negative SST anomalies in the Caribbean, simulates an intensification of northeasterly trade winds across Central America, increased evaporative cooling, and a band of increased rainfall in the northeastern tropical Pacific. These results are consistent with the alkenone SST and δD reconstructions that suggest increasing precipitation and SST cooling at the time of Heinrich event 1.
Description:
K. P.
and J. P. S. thank the Comer Science and Education Foundation for
financial support. J. P. S. acknowledges support by the National Science
Foundation (grant NSF-ESH-0639640). NSF grant OCE-0317702 funded
cruise KNR176 to the Panama Basin and L. D. K.’s results presented here.
A. T. is supported by the Japan Agency for Marine-Earth Science and
Technology. S. P. X. is supported by the National Oceanic and Atmospheric
Administration CLIVAR Program, the Japan Ministry of Education, Culture,
Science and Technology through the Kyosei-7 Project, and the Japan
Agency for Marine-Earth Science and Technology.
Keywords:
Past hydrologic changes
;
Eastern tropical Pacific
;
Compound-specific hydrogen isotope ratios
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
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