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

过去几次气候变化的温度信息缺乏，仍然是缩小未来气候预测不确定性的主要障碍。该项目旨在根据洞穴记录(洞穴)中测量的新温度指标，测量美国西南部和北部地区过去重要气候时期的古地表绝对温度。新产生的晚更新世和全新世的温度数据可能会为气候模型提供有用的约束。具体地说，研究人员的目标是使用双块状同位素和锶同位素提供北美大陆大片地区的温度信息。新的温度记录将被用来解决以下问题：1)北美大陆内部和整个大陆全新世温度变化的程度是什么？格陵兰岛和大陆替代记录(例如美国西南部)之间的协变在多大程度上反映了温度的变化，而不是水的同位素变化。研究人员已经从几个洞穴(卡尔斯巴德洞穴，Lechuguilla Cave-NM，Wind Cave-SD，Mammoth Cave-KY，Mystery Cave-MN，Hollyhock Hollow Caves-NY，以及这些地区不太知名的洞穴)收集了样本，这些洞穴从Laurentide冰盖延伸到沙漠西南部。对所选样品的多个亚样粉末(~200 mg)进行准确的铀系测年，将为更重要的时期(如中全新世、年轻仙女座、极外气候逆转(神秘间隔)、末次冰盛期、末次间冰期)的成团和锶同位素分析提供合适的亚样粉。这项工作还将描述这些时期美国西南部和更北部地区之间的温度梯度。潜在的更广泛的影响包括新的古温度记录，可以用来作为气候模型的基准，并评估温度对水文气候和水资源的影响。此外，这项应用双组分同位素和锶数据的研究可以为定量重建古气候提供新的方法学方法。该项目将为新墨西哥大学和密歇根大学的两名研究生提供研究培训。这项工作的结果将通过外展和媒体报道向更广泛的公众传播。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.