Seasonal to interannual climate variability in the tropical southwest Pacific during the last deglaciation - Monthly resolved reconstructions from Great Barrier Reef corals

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I suggest reconstructing the range of seasonality and interannual climate variability during the last deglaciation in the tropical southwest Pacific Ocean, by analysing the skeletons of annually-banded corals from the Great Barrier Reef. The corals will be recovered by IODP Expedition 325 (February 2010), a Mission Specific Platform Expedition conducted by the European Consortium for Ocean Research Drilling (ECORD). The analyses of Sr/Ca and oxygen isotope ratios in fossil corals will provide monthly resolved reconstructions of temperature and hydrologic balance at the sea surface for time windows of several decades, robustly resolving the annual cycle. These coral records, for the first time, will allow quantifying changes in the amplitude of seasonality and interannual climate variability in the tropical southwest Pacific that occurred from 20,000 to 10,000 years ago. Furthermore, the project can provide unique insights into the dynamics of natural modes of atmosphere-ocean variability on interannual timescales, such as the El Niño-Southern Oscillation and possibly the Indian Ocean Dipole, under boundary conditions different from today. Comparing such ultrahigh-resolution coral-based snapshots of last deglacial climate variability with state-ofthe- art climate model simulations will help to assess the validity of future greenhouse projections on timescales relevant for society. The suggested project addresses a major scientific objective of IODP Expedition 325.