Collaborative research: RUI: constraining tropical hydroclimate responses to periods of abrupt hydrological changes using cave deposits, cave monitoring, and model outputs

Award Details: Occidental College received a $313,622 Project Grant from the National Science Foundation (NSF) Division of Earth Sciences under the Geosciences program (CFDA 47.050) beginning September 1, 2025, and concluding August 31, 2028. This collaborative research initiative will produce foundational scientific understanding of tropical hydroclimate responses to abrupt hydrological changes, particularly during Heinrich Events in the Northern Hemisphere.

Products and Services: The award will generate three primary research deliverables: (1) a multi-year, multi-cave monitoring network in the Philippines to constrain seasonal variations in karst hydrology; (2) high temporal resolution cave geochemistry records spanning numerous Heinrich Events that reconstruct past hydrologic change over the Indian Pacific Warm Pool; and (3) geochemical data-model comparisons evaluating mechanisms driving geochemical variability during Heinrich Events. These research products will fill spatial gaps in western tropical Pacific climate data and improve model accuracy for predicting rainfall pattern changes during abrupt hydrologic variability. Additionally, the project will generate public engagement materials, including pamphlets, audio guides, and guided tours for national parks and UNESCO World Heritage sites, strengthening connections with protected landscapes and local stakeholder communities.

Abstract

The indian pacific warm pool located in the tropics is the heat engine of the globe. Previous work has proposed that past episodic freshwater fluxes known as heinrich events in the northern hemisphere abruptly modulate tropical hydroclimate in regions like the indian pacific warm pool. In this project, cave deposits from the philippines are used to reconstruct past hydrologic change and investigate the hydrologic response over the indian pacific warm pool to heinrich events. The philippines is ideally located for this work as IT is situated within the indian pacific warm pool and is sensitive to seasonal variations in rainfall associated with the asian monsoon systems. This work will accomplish three primary tasks: first, IT will expand current cave monitoring efforts in the philippines to encompass a multi-year, multi-cave monitoring network to better constrain seasonal variations in karst hydrology. Second, IT will contribute new high temporal resolution cave geochemistry records spanning numerous heinrich events. Third, geochemical data-model comparisons will be conducted to evaluate the mechanisms driving geochemical variability in these records during heinrich events. Results from this work will help develop a foundational understanding of rainfall pattern changes during abrupt hydrologic variability. By combining multi-year surface and subsurface karst monitoring with new cave records, the influence of northern hemisphere freshwater fluxes on tropical hydroclimate will be assessed. The project will also fill in spatial gaps in the western tropical pacific and improve model accuracy. This work will fortify connections with national parks/protected landscapes, unesco world heritage staff, and cavers. The team's findings will be incorporated in pamphlets/audio guides and guided tours for millions of domestic and international park visitors. Finally, the project includes training of multiple undergraduate students in the geosciences at occidental college and a graduate student from brown university. 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.- subawards are not planned for this award.