Collaborative Research: Reconstructing Holocene Climate Variability and the Indonesian Throughflow in the Western Equatorial Pacific

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Abstract: Under this award the proponents will determine the role of the Indonesian Throughflow (ITF) in Earth's climate through its effect on the heat and freshwater budgets and the air-sea heat fluxes of the Pacific and Indian Oceans. Estimates of salinity and temperature will be generated using d18O and Mg/Ca in benthic and planktonic foraminifera from the best sediment cores along depth transects between 300-700m water depth in the Makassar Strait. High accumulation rates will allow reconstruction centennial to millennial variability over the last ~14,000 years. Specific questions which will addressed: Are key elements of past climate variability in the western equatorial Pacific consistent with the hypothesis that variations in the amplitude and frequency of ENSO force changes in ITF on centennial to millennial time scales during the Holocene? Is the timing and amplitude of Holocene abrupt changes in ITF consistent with a link to broader tropical-scale climate change? Is there a link to extra-tropical changes? Was there a long-term change in ITF strength throughout the Holocene? How does that change compared with the ITF variability during the deglaciation? Did the apparent shift to more El Nino-like conditions in the late Holocene or the freshening of the western Pacific warm pool influence the ITF? Does the freshening trend reflect a regional response to southward migration of the ITCZ or an expansion of local, monsoon-derived freshwater inputs? The proposals broader impacts include several graduate and undergraduate students who will receive training related to this project and utilize data generated in this project as part of their undergraduate or graduate thesis.