COLLABORATIVE RESEARCH: Global Change and the Terrestrial Paleoclimate Record from Eastern North America: 600,000 years BP to Present

该奖项由2009年美国复苏与再投资法案(公法第111-5条)资助。智力价值：这笔赠款将支持从田纳西州东部、西弗吉尼亚州南部到西弗吉尼亚州东北部的N-S样带沿线多个洞穴系统中保存的多个洞穴系统中的多个洞穴系统中经过校准、高分辨率和绝对日期确定的稳定同位素和痕量金属时间序列的开发。现代区域气候显然对北大西洋和太平洋的海面变化很敏感，气候变化，特别是干旱和古干旱的发生，与仪器记录(如AMO、PDO/NPO)和古记录(如8200年邦德尺度周期事件)中的大尺度海洋和大气模式有关。此外，该团队将使用包括碳循环在内的完全耦合的气候模型，调查陆地和海洋对年轻仙女座开始时气候变化的地球化学反应。整合后，这项工作将产生一个独特的数据产品，评估该区域至少在过去六个冰川/间冰期周期内气候变化的时间、规模和根本原因。该项目基于洞穴的部分的具体成果是一个日期良好的综合时间序列，可用于评估气候可变性的模式和时间尺度，并在近海和较远的洞穴(例如，阿曼中国)和冰芯记录的背景下，评估导致气候不稳定和模式转变的潜在驱动机制。还将比较N-S样带沿线各个站点的时间序列，以评估气候边界变化的重要性。对研究样带43个洞穴的年代学控制(230年代)表明，通过海洋同位素第15阶段(~600KYR BP)重建区域气候变化具有特殊的潜力。这一日期为230年的时间序列将有助于定义人类活动时间尺度上的气候变化。具体地说，综合来自多个地点的几个高分辨率(数十年尺度)全新世洞穴喷发记录将1)确定时间，2)解决过去一万年来突然气候变化(例如8200年事件)的基础。此外，对晚更新世洞穴的类似研究将更全面地了解过去气候可能类似于(例如，信息系统-5、7、9、11、13、15)或不同于今天(信息系统-2、6、8、10、12、14)的具体气候模式是如何演变的。将利用拟议的洞穴滴水(del-18O、del-13C、微量金属)、洞穴环境(温度、湿度、二氧化碳)和洞穴上方大气/水文条件的同位素/地球化学校准研究结果，加强对晚第四纪气候历史的解释。模拟的结果-该项目的一部分将有助于理解快速气候变化时期的地球化学反馈和可能的放大或稳定因素，例如年轻的仙女座。拟议的研究涉及P2C2的关键倡议，包括1)评估与大规模耦合气候系统有明显联系的地区对气候模式变化的敏感性和响应，2)对突发和极端气候事件的响应评估，以及3)数据模型合成。更广泛的影响：拟议的研究将定义北美东部大西洋中部/阿巴拉契亚地区过去600,000年来的气候变化历史，这是一个具有国家重要性的人口稠密地区。该项目旨在提供有意义的实验室和现场导师/实习生机会，将三所大学的本科生与研究生和教师导师联系起来。私人投资机构代表三个不同的研究小组，致力于招募代表性不足的群体，包括女性和少数群体。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Intellectual Merit: This grant will support the development of calibrated, highly-resolved, and absolute-dated stable isotopic and trace-metal time series from multiple speleothems preserved in multiple cave systems along a N-S transect from East Tennessee, through southern West Virginia, to northeastern West Virginia. Modern regional climate is demonstrably sensitive to sea-surface variability of the North Atlantic and Pacific Oceans, and climate variability, in particular the occurrence of drought and paleo-drought, has been linked to large-scale oceanic and atmospheric patterns in the instrumental record (e.g., AMO, PDO/NPO) and in the paleo-record (e.g., Bond-scale cyclicity, 8200-year event). In addition, the team will investigate the geochemical response on land and in the ocean to climatic changes at the onset of the Younger Dryas, using a fully coupled climate model including a carbon cycle. When integrated, the work will yield a unique data product that evaluates the timing, magnitude, and underlying causes for climatic change in the region for at least the last six glacial/interglacial cycles.The specific deliverable for the speleothem-based portion of the project is a well-dated composite time series that can be used to assess the modes and timescales of climate variability, and, in the context of proximal marine and more distal speleothem (e.g., China, Oman) and ice-core records, evaluate the potential driving mechanisms responsible for climate instability and mode-shifts. Time series from individual sites along the N-S transect will also be compared in order to assess the importance of shifts in climatic boundaries. Geochronological control (230Th ages) on 43 speleothems from the study transect demonstrate that exceptional potential exists for reconstructing regional climate change back through Marine Isotope Stage 15 (~600 kyr BP). The 230Th-dated time series will help define climate shifts on timescales of human activity. Specifically, the integration of several highly-resolved (multidecadal-scale) Holocene speleothem records from multiple sites will 1) define the timing of, and 2) resolve the basis for abrupt climate change (e.g., 8200-year event) during the past ten millennia. Furthermore, similar studies of late Pleistocene speleothems will yield a more comprehensive understanding of how specific climate modes evolved in the past when climate was presumably similar to (e.g., MIS-5, 7, 9, 11, 13, 15) or different from (MIS-2, 6, 8, 10, 12, 14) today. Interpretation of the late Quaternary climate history will be strengthened using results from a proposed isotopic/geochemical calibration study of cave drip waters (del-18O, del-13C, trace-metal), cave environment (temperature, humidity, pCO2), and the atmospheric/hydrological conditions above the cave. Results from the modeling-part of the project will contribute to the understanding of geochemical feedbacks and possible amplifying or stabilizing factors at times of rapid climate change, such as the Younger Dryas.The proposed study addresses key initiatives of P2C2, including 1) assessment of sensitivity and response to climate mode changes in a region with demonstrable linkages to large-scale coupled climate systems, 2) assessment of responses to abrupt and extreme climate events, and 3) data-model synthesis.Broader Impacts: The proposed research will define the history of climate change during the last ~600,000 years for the mid-Atlantic/Appalachian region of eastern North America, a highly-populated region of national importance. The project is designed to provide meaningful lab- and field-based mentorship/traineeship opportunities that couple undergraduates with graduate-level and faculty mentors across three universities. The PIs represent three diverse research groups committed to recruitment of underrepresented groups, including females and minorities.