Evolution of the eastern tropical Pacific through Plio-Pleistocene glaciation

A tropical Pacific climate state resembling that of a permanent El Nino is hypothesized to have ended as a result of a reorganization of the ocean heat budget similar to 3 million years ago, a time when large ice sheets appeared in the high latitudes of the Northern Hemisphere. We report a high-resolution alkenone reconstruction of conditions in the heart of the eastern equatorial Pacific (EEP) cold tongue that reflects the combined influences of changes in the equatorial thermocline, the properties of the thermocline's source waters, atmospheric greenhouse gas content, and orbital variations on sea surface temperature (SST) and biological productivity over the past 5 million years. Our data indicate that the intensification of Northern Hemisphere glaciation similar to 3 million years ago did not interrupt an almost monotonic cooling of the EEP during the Plio-Pleistocene. SST and productivity in the eastern tropical Pacific varied in phase with global ice volume changes at a dominant 41,000-year (obliquity) frequency throughout this time. Changes in the Southern Hemisphere most likely modulated most of the changes observed.

Title	Evolution of the eastern tropical Pacific through Plio-Pleistocene glaciation
Creator	Herbert, T. D.
	Lawrence, Kira T.
	Liu, Z. H.
Publisher	Science
Academic Department	Geology & Environmental Geosciences
Division	Natural Sciences
Organization	Lafayette College
Date Issued	April 7, 2006
Date Available	2009-08-27T15:32:56Z
Type	Article
Language	English
Bibliographic Citation	Lawrence, K. T., Z. H. Liu, and T. D. Herbert. " Evolution of the eastern tropical Pacific through Plio-Pleistocene glaciation." Science 312 (5770): 79-83.
Standard Identifier	Handle 10385/542
Standard Identifier	DOI 10.1126/science.1120395
Permalink	http://hdl.handle.net/10385/542
Rights Statement	In Copyright
Rights Holders	American Association for the Advancement of Science