Dynamic millennial-scale climate changes in the northwestern Pacific over the past 40,000 years

Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 37 (2010): L23603, doi:10.1029/2010GL045202.Ice core records of polar temperatures and greenhouse gases document abrupt millennial-scale oscillations that suggest the reduction or shutdown of thermohaline Circulation (THC) in the North Atlantic Ocean may induce the abrupt cooling in the northern hemisphere. It remains unknown, however, whether the sea surface temperature (SST) is cooling or warming in the Kuroshio of the Northwestern Pacific during the cooling event. Here we present an AMS 14C-dated foraminiferal Mg/Ca SST record from the central Okinawa Trough and document that the SST variations exhibit two steps of warming since 21 ka — at 14.7 ka and 12.8 ka, and a cooling (∼1.5°C) during the interval of the Younger Dryas. By contrast, we observed no SST change or oceanic warming (∼1.5–2°C) during the episodes of Northern Hemisphere cooling between ∼21–40 ka. We therefore suggest that the “Antarctic-like” timing and amplitude of millennial-scale SST variations in the subtropical Northwestern Pacific between 20–40 ka may have been determined by rapid ocean adjustment processes in response to abrupt wind stress and meridional temperature gradient changes in the North Pacific.This research was funded by the National Science Council (NSC), Taiwan to M.T.C. (NSC96‐2611‐M‐019‐008 and NSC96‐2611‐M‐019‐009) and C.C.S. (NSC98‐2611‐M002‐006). X.P.L. was supported by the Natural Science Foundation of China (40930844 and 40706006), China’s National Basic Research Priorities Programmer (2005CB422303 and 2007CB411804), 111 Project (B07036), and the Program for New Century Excellent Talents in University (NECT‐07‐0781)