This project aims to build proxy records of speleothem stable isotopes to discern decadal to centennial scale variability in eastern African hydroclimate. The study site is sensitive to large- scale features of the global atmospheric circulation (El nino Southern Oscillation, Walker circulation, monsoon system) and new hydroclimate records will improve the understanding of the drivers of decadal to millennial hydroclimate change in this key region and beyond.
Specifically, the researchers will: 1) Establish a high?resolution multi-cave geochronology using extensive Uranium-Thorium (U-Th) dating to determine the duration and magnitude of hydroclimate changes in East Africa. These high-resolution dates will allow identification of active growth intervals vs dry intervals as expressed across the network of caves; 2) Characterize the role of different processes (e.g. large-scale atmospheric circulations and convective processes, local land-atmospheric processes such as re-evaporation etc, and karst hydrological processes such as mixing, recharge) on modern rainwater and dripwater oxygen stable isotopes via the monitoring of cave modern hydrology, analysis of instrumental climate data, and isotope-enabled climate model output; 3) Carry out high-resolution reconstructions of relatively short intervals at ~ 9000 years that are shared across several stalagmites as identified through the U-Th dating targeting.
The potential Broader Impacts include generating a detailed knowledge of the nature, timing, and local/regional extent of climatic and environmental changes in Eastern Africa over the last 11,500 years and links to large- scale features of the global atmospheric circulation. The project will provide training for undergraduate and graduate students and will contribute to training of next generation climate scientists particularly from underrepresented groups. Focus will be on cross training in analytical techniques, data analysis, and modeling. This project will facilitate knowledge-based international cooperation with Ethiopian universities.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
