Oregon State University, United States

High-resolution ( approximately 3-6 k.y.) upper ocean temperature and salinity estimates derived from planktic foraminiferal delta (super 18) O and Mg/Ca in Ocean Drilling Program (ODP) Site 1146 reveal stepwise changes in the precipitation-evaporation balance of the subtropical northwestern Pacific during the Middle Miocene (15.7 to 12.7 Ma). We attribute the punctuated pattern of surface warming and freshening following Antarctic ice growth episodes at 14.6, 14.2, 13.9, and 13.1 Ma to successive northward movements of the Intertropical Convergence Zone, implying high sensitivity of tropical rain belts to the interhemispheric temperature gradient driven by high-latitude climate. This dynamic interaction has implications for future warmer climate regimes with differential warming of the Northern Hemisphere, as it may lead to changes in the latitudinal penetration of tropical Pacific moisture over Southeast Asia.