EAPSI:Developing a Coral-Based Climate Reconstruction to Better Understand Tropical Pacific Hydroclimate

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The El Niño-Southern Oscillation, which originates in the tropical Pacific, can cause significant changes in climate and weather patterns across the globe, such as droughts and floods. How the El Niño-Southern Oscillation will respond to anthropogenic climate change remains unanswered in the scientific literature. Through a collaboration with Dr. Andrew Lorrey of the National Institute of Water and Atmospheric Research (NIWA) in New Zealand, this research will improve the scientific understanding of El Niño and La Nina events by collecting chemical measurements from coral reef samples to reconstruct changes in climate over intervals of the last millennium. Dr. Lorrey is an expert climatologist and curator of a south Pacific coral archive. This study will extend climate observations over a longer period of time allowing scientists to put current climate change into a longer paleoclimate context.In the southwestern tropical Pacific, the dominant climate feature is a band of low-level moisture, known as the South Pacific Convergence Zone. During an El Niño event, this zone shifts towards the equator, resulting in unusually dry conditions in the south Pacific and unusually wet conditions in the central equatorial Pacific. Over 100 coral samples have been collected from the southern Cook Islands and will be used to reconstruct hydrological changes associated with movements of the South Pacific Convergence Zone and the El Niño-Southern Oscillation. Well preserved coral samples will be radiometrically-dated and age-modeled using x-ray computed tomography techniques. Stable isotopes in the coral skeleton vary with temperature and hydrological changes. Therefore, corals can be used to model changes in climate. To reconstruct climate over the past millennium, I will sample pristine, well-dated coral samples with Dr. Andrew Lorrey and use instrumentation at NIWA in Auckland, New Zealand to prepare the coral samples for future isotopic analyses at the Paleoclimate Co-Laboratory at the University of Maryland. This award is funded in collaboration with the Royal Society of New Zealand.