Collaborative Research: P2C2--Testing the Tropical Storm and Tropical Cyclone Masking Hypotheses: Advancing Speleothem Reconstruction of Paleotempestology and Paleohydrology

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This project aims to use speleothems from caves on the Yucatan Peninsula to reconstruct quantitative precipitation and tropical cyclone (TC) records affecting the Caribbean and Gulf of Mexico regions spanning hundreds of thousands of years.The success of such reconstructions depends on understanding the relationship between local precipitation amount and precipitation delta 18-Oxygen isotope values (i.e. the amount effect) and how this relationship is preserved in stalagmite deposits. TC precipitation can shift the amount effect and it has been hypothesized that TC rain may therefore bias quantitative stalagmite delta 18-Oxygen isotope precipitation records (i.e. the TC masking hypothesis). Recent studies based on stalagmite delta 18-Oxygen isotope precipitation records, however, suggest that TC variability was linked to the collapse of the ancient Maya civilization (i.e., the tropical storm hypothesis). Available stalagmite delta 18-Oxygen isotope precipitation records to test this hypothesis have not yet been replicated and their precipitation estimates may reflect TC masking. Replication, furthermore, may be hindered by chronological uncertainty, the lack of equilibrium stalagmite delta 18-Oxygen isotope values and regional climate variability. The researchers therefore will: (i) apply a promising approach for replication of available stalagmite delta 18-Oxygen isotope based precipitation records during selected intervals spanning the last 2000 years; (ii) examine quantitatively the TC masking influence on the amount effect and on stalagmite precipitation records; and (iii) test the tropical storm hypothesis by applying an ultrahigh resolution sampling approach to detect the particular isotopic signature from individual TCs in three known stalagmites (i.e., CH-1, Chaac, Itzamna).The potential Broader Impacts include improved understanding of tropical cyclone (TC)-climate relationships under different climate states and over long timescales. Such understanding is critical for accurate projections and TC risk assessment and mitigation in a changing climate. This project supports a female lead investigator at an undergraduate liberal arts college. It will provide significant research experience for several undergraduates and the researchers have a strong history of supporting women and underrepresented minority students. One of the lead researchers is an early-career Hispanic faculty member and this project would support the work of this researcher and two female Hispanic PhD students. This work would potentially help further develop methods for speleothem-based paleotempestology and would highlight the need to consider TC masking in other tropical speleothem records. Finally, this work will be of interest to the archaeology research community as it can help address the role of TCs in societal changes in Latin America.