EAGER: Documenting the Spatial Pattern of Drought in Western North America During the Holocene

北美西部的干旱限制了市政、农业、林业、水电、渔业和娱乐用水，从而影响了环境和经济。水资源有限的问题将因美国西部人口的快速增长以及高山积雪和冰川的消失而变得更加复杂。这个问题在该地区的南部地区尤其困难，那里的高山积雪目前在夏季旱季缓冲了溪流。记录过去干湿循环的时间、规模、持续时间和地理模式是了解干旱原因的重要一步。 这项研究将帮助科学家了解干湿循环的频率、持续时间和幅度，帮助正确看待目前影响该地区的干旱，并帮助政策制定者制定更明智的水资源计划。 这项EAGER赠款将使用来自不列颠哥伦比亚省的全新世湖泊沉积物记录，重建北美西部山脉沿着干旱和洪水周期的时空模式，并帮助确定这些事件的根本原因。我们的目标是重建两个定量全新世古降水记录使用一致的多代理方法，并比较结果正在进行的工作在北美西部的科迪勒拉山脉类似的湖泊。位于中部和北方不列颠哥伦比亚省的拟定地点包含许多湖泊，其地质和湖沼学特征与之前在华盛顿、俄勒冈州、蒙大拿州和育空地区研究的湖泊相似。 科学家们将从产生和保存自生碳酸钙的湖泊中开发出日期明确的稳定同位素数据系列。这种碳酸盐记录了湖水随时间变化的氧同位素信号，反映了干旱的频率和持续时间。这些数据将用于气候模型，以便：（i）定量解释现有的代用数据，（ii）确定影响干旱模式的频率和强度的因素，如涉及厄尔尼诺南方涛动-热带太平洋气候动力学和大西洋经向翻转环流的天气遥相关，并对其进行排序，最重要的是，减少未来干旱模式对人为强迫的响应的概率预测的不确定性。

Drought in western North America impacts the environment and economy by limiting water for municipalities, agriculture, forestry, hydropower, fisheries and recreational uses. The problem of limited water resources will be compounded by rapid population growth in the western U.S. and the loss of alpine snowpack and glaciers. This problem will be especially difficult in the southern reaches of this region, where alpine snowpack currently buffers stream flow during the summer dry season. Documenting the timing, magnitude, duration and geographic pattern of past wet and dry cycles is an important step toward understanding the causes of droughts. This research will help scientists understand the frequency, duration and magnitude of wet and dry cycles, help place the current drought impacting the region in perspective, and aid policy makers so that they can make better-informed plans regarding water resources. This EAGER grant will use Holocene lake sediment records from British Columbia to reconstruct the spatial and temporal patterns of drought and pluvial cycles along the cordillera of western North America and help identify the underlying causes of these events. The goal is to reconstruct two quantitative Holocene paleoprecipitation records using consistent multiproxy methods, and to compare the results to ongoing work on similar lakes in the western cordillera of North America. The proposed locations in central and northern British Columbia contain numerous lakes with geological and limnological characteristics similar to lakes previously studied in Washington, Oregon, Montana, and the Yukon Territory. The scientists will develop well-dated stable isotope data series from lakes that produce and preserve authigenic calcium carbonate. This carbonate records the oxygen isotope signal of lake water over time, which reflects the frequency and duration of droughts. This data will then be used in climate models to: (i) quantitatively interpret existing proxy data, (ii) identify and rank the factors that influence the frequency and intensity of aridity patterns such as synoptic teleconnections involving both El Niño Southern Oscillation-tropical Pacific climate dynamics and the Atlantic Meridional Overturning Circulation, and most importantly, (iii) reduce the uncertainty in probabilistic forecasts of future drought pattern responses to anthropogenic forcing.