CAREER: California Megadroughts in Context: Integrating High Resolution Speleothem Records with Isotope-enabled Climate Models and Translating Climate Data for the K-12 Classroom

CAREER项目的总体目标是将加州两个洞穴的高分辨率、多代理的气候变化洞穴记录与同位素支持的古气候模型相结合，以限制降水数量和来源的变化，并确定加州水文变化的驱动因素，包括严重干旱。洞穴记录（即氧和碳同位素、晶体结构、微量元素、锶和铀同位素）将从洞穴监测中得到发展。将使用支持同位素的反应输运建模工具来解析环境代理中多个相互关联的环境影响。这项研究将通过对关键气候转变进行高分辨率测量，并通过研究洞穴滴水中铀同位素比率的时空变化，有助于推进洞穴初始铀同位素比率，这是一种新兴的渗透速率代理。在该项目中开发的加利福尼亚中部和北部的洞穴记录将与其他区域记录相结合，以创建美国西海岸降水变化的时变地图。将这些地图与同位素支持的末次消冰和全新世时间段气候模型进行定量比较，将有助于阐明降水变化和区域气候变率背后的驱动机制。研究的预期结果包括：1)发展了美国西海岸降水变异性的历史，该历史由多个代理的重叠石笋记录组成，可延伸至距今33,000年；2)用同位素激活反应输运模型对代理数据和监测数据进行交叉验证；3)评价岩石层初始铀同位素比值作为古渗透指标；4)现代降水对海洋-大气振荡响应对比站点的年际至多年代际降水变率详细记录以及这些模式随时间演变的前景；5)通过代理模式比较评估加州降水变率的驱动机制，包括特大干旱条件；6)提高了对水分来源变化在干旱条件发展和衰减中的作用的认识。该教育计划建立在研究人员与范德比尔特大学科学与数学学院（SSMV）的持续关系基础上，通过对来自纳什维尔大都会公立学校（MNPS）的高中生团队的多年指导，他们将进行实地实验，地球化学研究，并最终创建一个用于田纳西州课堂的在线教育工具。在线门户网站的目标是以一种对教师有用和可访问的方式呈现在线可用的丰富的气候和古气候数据，希望通过使数据驱动的、沉浸式的气候科学学习更容易实现，从而改变K-12课堂上教授气候科学的方式。该项目将涉及研究生、本科生和高中生，制作一种教育产品，对田纳西州的科学教室和其他地方产生持久的积极影响。

This CAREER project generally aims to integrate high-resolution, multi-proxy speleothem records of climate change during the last deglaciation and Holocene from two California caves with isotope-enabled paleoclimate models in an effort to constrain changes in precipitation amount and source and identify the drivers of hydrologic change in California, including severe drought. Speleothem records (i.e., oxygen and carbon isotopes, crystal fabrics, trace elements, strontium and uranium isotopes) will be developed from cave monitoring. An isotope-enabled reactive transport modeling tool will be used to parse the multiple interrelated environmental influences on environmental proxies. This research will help advance speleothem initial uranium isotope ratios, an emerging proxy for infiltration rate, by conducting high-resolution measurements through key climatic transitions and by investigating the spatial and temporal variability of Uranium isotope ratios in cave drip water. Central and northern California speleothem records developed in this project will be integrated with other regional records to create time-varying maps of precipitation change along the U.S. west coast. Quantitative comparison of these maps with isotope-enabled climate models for time slices through the last deglaciation and Holocene will help clarify the driving mechanisms behind precipitation change and regional climate variability. Expected outcomes of the research include: 1) development of a history of precipitation variability along the U.S. west coast consisting of overlapping stalagmite records from multiple proxies for extending to 33,000 years before the present; 2) cross-validation of proxy and monitoring data with isotope-enabled reactive transport models 3) evaluation of speleothem initial Uranium isotope ratios as a paleo-infiltration indicator; 4) detailed records of inter-annual to multi-decadal precipitation variability at sites with contrasting modern precipitation responses to ocean-atmosphere oscillations and perspective on the evolution of these patterns through time; 5) evaluation of the driving mechanisms of California precipitation variability, including megadrought conditions, through proxy-model comparisons; and 6) improved understanding of the role of changing moisture source in the development and decay of drought conditions.The education plan builds on the researcher's ongoing relationship with the School for Science and Math at Vanderbilt University (SSMV) through multi-year mentoring of a team of high school students from the Metropolitan Nashville Public Schools (MNPS) who will conduct field experiments, geochemical research, and ultimately, the creation of an online educational tool for use in Tennessee classrooms. The goal of the online portal is to present the wealth of climate and paleoclimate data available online in a way that is useful and accessible for teachers, with the hope of transforming the way climate science is taught in K-12 classrooms by making data-driven, immersive learning on this topic more achievable. This project will involve graduate, undergraduates, and high school students to produce an educational product that has the potential for a lasting positive influence on Tennessee science classrooms and beyond.