Tropical South Pacific sea surface temperatures during the last deglaciaton from Tahiti corals

International audienceCoral Sr/Ca-based reconstructions have revealed a larger amplitude of sea surface temperature (SST) changes throughout the last deglaciation relative to foraminiferal Mg/Ca and alkenone-based SST reconstructions in the tropical Atlantic and the tropical southwestern Pacific. Here we present new coral Sr/Ca records from Tahiti in the central tropical South Pacific derived from fossil Porites sp. colonies drilled during IODP Expedition 310 (Tahiti Sea Level). These corals provide subseasonally resolved snapshots of tropical Pacific climate during the last deglaciation, accurately dated by U-series. We use (1) several living Porites colonies as a robust modern benchmark to take into account between-colony offsets in mean Sr/Ca of modern Tahiti Porites corals, (2) a thorough diagenetic screening procedure, and (3) a common aragonite standard to correct for inter-laboratory offsets in mean Sr/Ca. Based on this approach we conclude that early Holocene SST was not significantly lower than today and that early last deglacial SST was not lower by several degrees relative to modern SST in this region of the tropical Pacific, as reported in earlier coral Sr/Ca-based reconstructions from the tropical oceans. However, our results indicate a significant cooling during the Younger Dryas consistent with earlier results from Vanuatu in the western tropical South Pacific. Our new coral Sr/Ca-based SST estimates from Tahiti in the central tropical South Pacific provide a supplement to foraminiferal Mg/Ca and alkenone-based reconstructions of tropical Pacific SST, which are available from the far western and eastern part of the basin only