Collaborative Research: Evaluating Hydrologic and Ecologic Responses to late-Glacial (9-33ka) Abrupt Climatic Transitions in the Coastal southwest United States

美国西南部沿海地区的气候预测预测降水的频率和强度将发生变化，可能会出现整体干旱。尽管模型预测存在不确定性，但很明显，该地区冬季主导的“盛宴或饥荒”水文气候学的任何变化都将对人口稠密、水资源紧张的地区产生影响。该提案开发了一个从埃尔西诺湖，加州使用物理（粒度），生物（花粉），化学（C：N），和同位素（叶蜡氢同位素）analysis.Characterized异常分辨率和档案的连续性，在沿海西南部这个独特的陆地网站提供了一个无与伦比的机会，以评估水文和生态变化跨越突然的气候转变在晚冰期（9- 33 ka）。将使用多种多样的多代理方法来描述岩心的特征，以捕获大幅度的晚冰期过渡，包括叶蜡D/H每千分之100的变化，可变径流的粒度证据，以及流域植被变化的孢粉学证据。埃尔西诺湖的特殊档案的特点是连续沉积，高沉积速率，并使用离散的有机材料非常高分辨率的放射性碳年龄控制的能力。除了代表过去的陆地环境变化的高质量档案，埃尔西诺湖沉积物将使建议的相关性与已公布的海洋重建，包括当地和远端海洋记录的太平洋海面温度（SST），以及大西洋SST和经向翻转环流的证据，以评估该地区的水文和生态变化的驱动因素。该团队将专注于全球气候突变，包括Heinrich事件1-3，以及Bolling-Allerod和Younger Dryas的转变。虽然这些转变与预测的人为气候变化不同，但它们提供了大幅度的突然转变，能够提供对强迫-响应关系的最大见解。工作假设是，水文变化和生态变化是密切同步的，并响应于当地和全球气候突变的晚冰期至全新世早期。问题是这些地方反应的程度和速度，以及对未来的影响。首席研究员所在的加州州立大学富勒顿分校接触到大量少数族裔学生，特别是西班牙裔学生。该提案聘请了两名女性共同研究员，其中一人是早期职业助理教授。这项研究将为三个机构的研究生和本科生提供培训和研究机会，重点是建立分析和解释技能，这项研究还将提供第一个基于陆地的，十年到亚百年尺度的记录，了解西南沿海植被如何应对气候突变。过去的水文和生态变化的原因，响应和恢复的基线理解的发展是超出了古气候领域的生态学家，自然资源保护主义者的影响，和政策决定有关的加州植物多样性热点的兴趣。

Climate projections for the coastal southwestern United States predict a change in the frequency and magnitude of precipitation, perhaps with an overall drying. Despite the uncertainty in model projections, it is clear that any change to the region's winter dominated, "feast or famine" hydroclimatology will have consequences for the highly-populous, water-stressed region. This proposal develops a decadal to subcentennial scale, continuous sedimentary archive from Lake Elsinore, California using physical (grain size), biological (pollen), chemical (C:N), and isotopic (leaf wax hydrogen isotopes) analyses.Characterized by exceptional resolution and archive continuity, this unique terrestrial site in the coastal southwest offers an unparalleled opportunity to evaluate hydrologic and ecologic change across abrupt climatic transitions during the late Glacial period (9-33ka). The cores will be characterized using a diverse, multi-proxy approach to capture large magnitude, late Glacial transitions, including leaf wax D/H shifts of 100 per mil, grain size evidence for variable run-off, and palynological evidence for changes in catchment vegetation. Lake Elsinore's exceptional archive is characterized by continuous deposition, high sedimentation rates, and the capacity for very high resolution radiocarbon age control using discrete organic material. Beyond representing a high quality archive of past terrestrial environmental change, Lake Elsinore sediments will enable proposed correlations with published marine reconstructions including local and distal marine records of Pacific sea surface temperatures (SSTs), as well as Atlantic SSTs and evidence for Meridional Overturning Circulation in order to assess the driving causes of the region's hydrologic and ecologic change. The team will focus on global abrupt climatic transitions including Heinrich events 1-3, and the transitions into and out of the Bolling-Allerod and the Younger Dryas. Although these transitions differ from the projected anthropogenic climate change, they offer large magnitude, abrupt transitions capable of providing maximum insights into forcing-response relationships. The working hypothesis is that hydrologic changes and ecologic shifts are closely in step and responding to local and global abrupt climatic transitions in the late Glacial to early Holocene. The questions are how much and how fast are these local responses demonstrated, and what might be the implications for the future.The lead investigator's institution, Cal State Fullerton, reaches a large number of minority, and especially Hispanic students. The proposal engages two female co-investigators, one of whom is an early career Assistant professor. The proposed study will provide training and research opportunities for graduate and undergraduate research at three institutions, with a focus on building the analytical and interpretative skill sets.This research will also provide the first terrestrially-based, decadal to subcentennial scale record of how the vegetation of the coastal southwest responds to abrupt climatic transitions. The development of a baseline understanding of the causes, responses, and recovery of past hydrologic and ecologic change is of interest beyond the paleoclimate field with implications for ecologists, conservationists, and policy decisions pertaining to the California Floristic Biodiversity Hotspot.