Collaborative Research: P2C2--Continental Temperature Variability during Greenland Stadials and Interstadials from Subaqueous Speleothems

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The lack of temperature information for past episodes of climate change remains a major hinderance to narrowing uncertainties of future climate projections. This project aims to measure absolute paleo-surface temperatures for important past climate periods in both the southwestern and northern regions of the United States based on novel temperature indicators measured in cave records (speleothems). The newly generated temperature data for the late Pleistocene and Holocene can potentially provide useful constraints for climate models.Specifically, the researchers aim to provide temperature information for a large region of the North American continent using dual clumped isotope and strontium isotopes. The new temperature records will be used to address the following questions: 1) what was the extent of Holocene temperature variability in and across the continental interior of North America? To what extent does the covariation between Greenland and continental proxy-records (e.g., southwestern United States), reflect temperature changes and not water isotope variability. The researchers have already the samples in hand collected from several caves (Carlsbad Cavern-NM, Lechuguilla Cave-NM, Wind Cave-SD, Mammoth Cave-KY, Mystery Cave-MN, Hollyhock Hollow caves-NY, and lesser-known caves in these areas) extending from the Laurentide ice sheet to the Desert southwest. Accurate uranium-series dating of multiple subsample powders (~200 mg) from selected samples will provide suitable subsample powders for clumped and Sr isotope analyses of the more important time periods (e.g., Middle Holocene, Younger Dryas, Extrapolar Climate Reversal (Mystery Interval), Last Glacial Maximum, the Last Interglacial). This work will also characterize temperature gradients between the southwestern United States and the more northern sites for these periods.The potential Broader Impacts include new paleotemperature records that can be used to benchmark climate models and to evaluate the impact of temperature on hydroclimate and water resources. Additionally, the research with the application of dual clumped isotopes and strontium data can yield novel methodological approaches for quantitative paleoclimate reconstructions.The project will provide research training for two graduate students at the universities of New Mexico and Michigan. The results of this work will be disseminated to the broader public via outreach and media coverage.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.