P2C2: A Speleothem and Cave Monitoring Research Program to Reconstruct the Paleoclimatology of the Yucatan Peninsula--Testing Modes and Causes of Variability in the North American

尽管观测到的水文循环加剧，包括干旱、洪水和热带气旋等极端事件的发生率增加，但历史记录的篇幅不够长，也不确定，无法明确地将观测到的特定极端水文事件归因于人为原因和/或气候变化的内部模式。该项目旨在从尤卡坦半岛(加勒比和墨西哥湾地区)的石笋中产生降水记录，并通过将这些记录与气候模型模拟相结合，研究热带水气候变化的根本原因机制。研究人员将分析包括氧和碳同位素以及微量元素在内的多种示踪剂，以重建加勒比海和墨西哥湾地区在关键气候时期：全新世、最后一次冰川和海洋同位素阶段8-9期间的降水变异性。此外，他们还将扩大2014年开始的地表和洞穴条件的环境和地球化学监测系统，以调查当地降雨量与降水的氧同位素和石笋同位素和元素组成之间的关系。新的监测系统将包括实地工作，以了解植被变化和以前的方解石降水对石笋碳同位素组成的影响。结合尤卡坦半岛新的石笋古气候记录，监测将有助于检验各种假设，这些假说涉及石笋稳定同位素和元素组成的环境控制、干旱在玛雅文明发展中的作用以及海因里希事件(寒冷时段)与加勒比海北部和墨西哥湾地区降水量下降之间的潜在联系。潜在的更广泛的影响包括描述和更好地了解在人口稠密和脆弱的地理区域(加勒比和墨西哥湾)的水文气候变异性和超出仪器记录的热带气旋。其他更广泛的影响包括两名博士生的科学培训、指导和专业发展，其中一名是马萨诸塞州大学的一名美国原住民女学生，另一名是研究人员将通过AGU-Bridge项目招募的另一名学生。该项目还将支持两名职业生涯早期和中期的研究人员。此外，研究人员和学生将参与公共外联活动，包括为里约秘密洞穴(墨西哥尤卡坦半岛)工作人员进行科学讲座。以前的洞穴监测工作和对这个洞穴的古气候研究已经成功地纳入到洞穴保护工作中，并被纳入每年有数千名游客的导游分享的信息中。这一古气候研究计划将促进与当地研究人员和社区的国际合作和参与。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。

Despite the observed intensification of the hydrological cycle including the increased incidence of drought, flooding and extreme events such as tropical cyclones, the historical record is insufficiently long and uncertain to enable the firm attribution of specific observed extreme hydrological events to an anthropogenic cause and/or to internal modes of climate variability. This project aims at producing precipitation records from stalagmites located in the Yucatan Peninsula (Caribbean and Gulf of Mexico regions), and at examining underlying causal mechanisms of tropical hydroclimate change by integration of these records with climate model simulations. The researchers will analyze multiple tracers including Oxygen and Carbon isotopes and trace elements to reconstruct precipitation variability in the Caribbean and Gulf of Mexico regions during key climate periods: the Holocene, the last glacial and during marine isotope stages 8-9. In addition, they will expand an environmental and geochemical monitoring system of surface and cave conditions that started in the year 2014, to investigate the relationship between local precipitation amount, and the Oxygen isotopes of precipitation and stalagmite isotopic and elemental composition. The new monitoring system will include fieldwork to understand the role of vegetation shifts and prior calcite precipitation on the carbon isotopic composition of stalagmites. The monitoring, in conjunction, with the new stalagmite paleoclimate records from the Yucatan Peninsula would help test various hypotheses concerning the environmental controls of the stable isotopic and elemental composition of stalagmites, the role of drought in the development of the Maya civilization, and potential links between Heinrich events (cold intervals) and precipitation declines in the northern Caribbean and Gulf of Mexico region. The potential Broader Impacts include a characterization and better understanding of hydroclimate variability and tropical cyclones beyond the instrumental record in a densely and vulnerable geographic area (Caribbean and Gulf of Mexico). Other Broader Impacts include the scientific training, mentorship and professional development of two Ph.D students including one female Native American student at UMASS and a second student that the researchers will recruit through the AGU-Bridge program. The project will also support two early and mid-career researchers. Additionally, the researchers and students will engage in public outreach activities including scientific lectures for the Rio Secreto Cave (Yucatan Peninsula, Mexico) staff. Previous cave monitoring work and paleoclimate studies from this cave have been successfully incorporated in the cave conservation efforts, and in the information shared by tour-guides with thousands of visitors per year. This paleoclimate research program will foster international collaborations and engagement with local researchers and communities.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.