A Terrestrial Perspective of Last Millennium Hydroclimate Variability in the Central Tropical Pacific

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The tropical Pacific plays an enormous role in shaping global climate patterns, yet our understanding of how tropical Pacific climate has varied in the past remains uncertain due to sparse observations across this vast region. This research project will use lake sediments to reveal changes in precipitation and evaporation on the central tropical Pacific island of Kiritimati during the last 1000 years. The outcomes of this project will provide insight into the nature of multidecadal to centennial tropical Pacific climate variability, timescales critical in the context of future climate trends.The proposed research will produce new proxy records of central tropical Pacific climate. Time series of elemental abundance, biological indicators of lake water conductivity, and stable oxygen isotope ratios of ostracod calcium carbonate spanning the last millennium will provide a multi-proxy perspective on past lake water balance and atmospheric moisture balance. In addition, new weather, limnologic and stable oxygen isotope measurements of lake and groundwater will promote a more quantitative understanding of the climate controls on lake water balance within the framework of a proxy system model for lake water and ostracod oxygen isotope ratios. These newly developed records will permit hypothesis testing of whether meridional or zonal changes in atmospheric circulation played a more prominent role in controlling spatial patterns of tropical Pacific hydroclimate variability.