AGS-PRF: Reconstructing Late Pleistocene East African Hydroclimate from Triple Oxygen Isotopes: A Novel Multi-Proxy Approach

Moerman Jessica W, Atlanta GA

Investigators

Abstract

This AGS PostDoctoral Research Fellow (PRF) award supports efforts to generate a ~600,000-year-long record of equatorial East African hydroclimate and water balance by analyzing a suite of carbonate isotope proxies from a well-dated paleo-lake core. This dataset will allow the response of East African hydroclimate to different orbital configurations and insolation regimes to be examined over multiple precession and eccentricity cycles. The research represents the first application of triple oxygen isotopes for paleoclimate reconstruction from sedimentary carbonate. By combining triple oxygen isotopes, recently shown to be sensitive recorders of evaporative processes, with more traditional isotopic proxies, the researcher aims to isolate the influence of evaporation on water balance. Carbonate triple oxygen isotopes are a highly promising but yet-to-be exploited tool for reconstructing past tropical hydroclimate. The proposed research will advance fundamental knowledge of triple oxygen isotope variability in lake carbonate archives and their utility as Precipitation-Evaporation (P-E) proxies. These results will provide a possible roadmap for integrating triple oxygen isotopes into investigations of past water balance in other arid regions where evaporation is an important control. The data-model comparison between the record generated in this project and isotope-equipped climate model simulations will provide critical insight into the dynamics driving East African hydroclimate variability, thus aiding the assessment of model performance and improvement of future water availability projections in drought-sensitive areas. The project involves interdisciplinary research combining methods and approaches from the fields of isotope geochemistry, paleoclimatology, and climate dynamics. The project also includes outreach and mentorship activities to underrepresented STEM groups and public outreach to adult faith communities through: (1) the NeXXt Scholars Program, which serves undergraduate women pursuing Science, Technology, Engineering, and Mathematics (STEM) majors; (2) the Johns Hopkins University STEM Achievement in Baltimore Elementary Schools (SABES) program; and (3) partnerships with the Evangelical Environmental Network and Young Evangelicals for Climate Action.