Sea surface temperature changes over the past 3 Terminations at the Southern Margin of the Western Pacific Warm Pool

Western Pacific Warm Pool (WPWP) is one of the most important sources of heat and moisture to the mid- to high-latitude regions. The global climate change is strongly influenced by the WPWP evolution (e.g, Stott et al., 2002, Science 297, 222-226; Linsley et al., 2010, Nature Geoscience 3, 578-583). However, the detailed glacial-interglacial dynamics of the WPWP and the driving forcings need to be further clarified. For better understanding the mechanism, we measured Mg/Ca ratios of planktonic foraminifera, Globigerinoides ruber (250-300 μm) of a sediment core MD05-2925 (9°20.61’S, 151°27.61’E) over the past 316 thousand years in the southern margin of the WPWP. Low ratios of Al/Ca and Mn/Ca and a shallow water depth of 1642 m indicate no detectable high magnesium contamination from ferromanganese oxide and clay minerals, little dissolution effect, and corroborate the validity of Mg/Ca thermometry. The determined G. ruber Mg/Ca record shows an averaged low glacial value of 3.4-3.6 mmol/mol and high interglacial value of 4.8-5.0 mmol/mol. The glacial-interglacial variation is about 1.3-1.6 mmol/mol. The Mg/Ca-inferred SST data show the glacial SST of 24-25 °C is 3-4 °C lower than the interglacial temperature of 27-28 °C. Maximum SST, 28-29 °C, at the MIS 5e was 1 °C higher than that in the Holocene. The reconstructed SST variability over the past 3 Terminations shows a strong 21-thousand-year periodicity. The observation reflects the precession cycle could be one of important orbital forcings to derive latent heat and moisture to high latitudes.