The History of South American Tropical Precipitation for the Past 25,000 Years

Authors

Paul A. Baker, Duke UniversityFollow
Geoffrey O. Seltzer, Syracuse University
Sherilyn C. Fritz, University of Nebraska-LincolnFollow
Robert B. Dunbar, Stanford University
Matthew J. Grove, Duke University, Division of Earth and Ocean Sciences, Durham, NC
Pedro M. Tapia, University of Nebraska-Lincoln
Scott L. Cross, Duke University, Division of Earth and Ocean Sciences, Durham, NC
Harold D. Rowe, Stanford University
James P. Broda, Woods Hole Oceanographic Institution, Woods Hole, MA

Date of this Version

January 2001

Comments

Published in SCIENCE26 JANUARY 2001 VOL 291. Copyright 2001. Used by permission. www.sciencemag.org

Abstract

Long sediment cores recovered from the deep portions of Lake Titicaca are used to reconstruct the precipitation history of tropical South America for the past 25,000 years. Lake Titicaca was a deep, fresh, and continuously overflowing lake during the last glacial stage, from before 25,000 to 15,000 calibrated years before the present (cal yr B.P.), signifying that during the last glacial maximum (LGM), the Altiplano of Bolivia and Peru and much of the Amazon basin were wetter than today. The LGM in this part of the Andes is dated at 21,000 cal yr B.P., approximately coincident with the global LGM. Maximum aridity and lowest lake level occurred in the early and middle Holocene (8000 to 5500 cal yr B.P.) during a time of low summer insolation. Today, rising levels of Lake Titicaca and wet conditions in Amazonia are correlated with anomalously cold sea-surface temperatures in the northern equatorial Atlantic. Likewise, during the deglacial and Holocene periods, there were several millennial-scale wet phases on the Altiplano and in Amazonia that coincided with anomalously cold periods in the equatorial and high-latitude North Atlantic, such as the Younger Dryas.