CAREER: California Megadroughts in Context: Integrating High Resolution Speleothem Records with Isotope-enabled Climate Models and Translating Climate Data for the K-12 Classroom

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This CAREER project generally aims to integrate high-resolution, multi-proxy speleothem records of climate change during the last deglaciation and Holocene from two California caves with isotope-enabled paleoclimate models in an effort to constrain changes in precipitation amount and source and identify the drivers of hydrologic change in California, including severe drought. Speleothem records (i.e., oxygen and carbon isotopes, crystal fabrics, trace elements, strontium and uranium isotopes) will be developed from cave monitoring. An isotope-enabled reactive transport modeling tool will be used to parse the multiple interrelated environmental influences on environmental proxies. This research will help advance speleothem initial uranium isotope ratios, an emerging proxy for infiltration rate, by conducting high-resolution measurements through key climatic transitions and by investigating the spatial and temporal variability of Uranium isotope ratios in cave drip water. Central and northern California speleothem records developed in this project will be integrated with other regional records to create time-varying maps of precipitation change along the U.S. west coast. Quantitative comparison of these maps with isotope-enabled climate models for time slices through the last deglaciation and Holocene will help clarify the driving mechanisms behind precipitation change and regional climate variability. Expected outcomes of the research include: 1) development of a history of precipitation variability along the U.S. west coast consisting of overlapping stalagmite records from multiple proxies for extending to 33,000 years before the present; 2) cross-validation of proxy and monitoring data with isotope-enabled reactive transport models 3) evaluation of speleothem initial Uranium isotope ratios as a paleo-infiltration indicator; 4) detailed records of inter-annual to multi-decadal precipitation variability at sites with contrasting modern precipitation responses to ocean-atmosphere oscillations and perspective on the evolution of these patterns through time; 5) evaluation of the driving mechanisms of California precipitation variability, including megadrought conditions, through proxy-model comparisons; and 6) improved understanding of the role of changing moisture source in the development and decay of drought conditions.The education plan builds on the researcher's ongoing relationship with the School for Science and Math at Vanderbilt University (SSMV) through multi-year mentoring of a team of high school students from the Metropolitan Nashville Public Schools (MNPS) who will conduct field experiments, geochemical research, and ultimately, the creation of an online educational tool for use in Tennessee classrooms. The goal of the online portal is to present the wealth of climate and paleoclimate data available online in a way that is useful and accessible for teachers, with the hope of transforming the way climate science is taught in K-12 classrooms by making data-driven, immersive learning on this topic more achievable. This project will involve graduate, undergraduates, and high school students to produce an educational product that has the potential for a lasting positive influence on Tennessee science classrooms and beyond.