A new regional paleo-precipitation proxy: oxygen isotopes in desert nitrate

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).A new regional paleo-precipitation proxy: oxygen isotopes in desert nitrateGregory MichalskiPurdue UniversityEAR - 0922114ABSTRACTPerhaps the most important unanswered question facing the climatologists, policy makers, and humanity at large is how will the anticipated global warming impact regional rainfall patterns? Our best tool for assessing how precipitation patterns in arid regions are likely to change in a warmer world is by using proxy validated global and regional climate models. Therefore it is imperative that new climate proxies that reflect local-regional precipitation variations over time and space be developed. The proposed research will demonstrate how 17O isotopic anomalies in soil nitrate can be used as a sensitive new proxy of mean annual precipitation in 36Cl dated Atacama Desert soils that are ~ 1,000,000 years old. This new proxy will be used to assess El Nino climate anomalies over the past million years at approximately 3,000 year resolution. This resolution if fine enough to capture climate change impacts arising from orbital precession and axial tilt, and at the same time lengthy enough to capture the last 5 orbital eccentricities (the full Milankovitch cyclcle), a feat few terrestrial proxies can capture. The proposed research links atmospheric chemistry to climatology and will provide real data to assess coupled chemical transport-meteorological models such as WRF-Chem, currently under development by NOAA, EPA and other NGO¡¦s. The research will highlight the new applications using ?´17O anomalies to a wider science community. The main outcome is a better understanding of how regional precipitation might change with the anticipated global warming in the coming decades.