Drought or Deluge? Columbia River flows to the North Pacific under a variable Holocene climate.

干旱还是洪水？

• 批准号: 2149564
• 负责人: Maureen Davies Walczak
• 金额: $ 87.69万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149564&HistoricalAwards=false
• 关键词: Drought; Deluge; Columbia; River; flows

Drought or Deluge? Columbia River flows to the North Pacific under a variable Holocene Climate The discharge of the Columbia River broadly reflects the water supply of the Pacific Northwest region. Little is known about the long-term influence on climate variability on this water supply prior to the 20th century, leading to uncertainty surrounding the impacts of the currently warming climate on regional water rights, agricultural production, and fisheries. This research aims to reconstruct the natural variability in river discharge via chemical and biotic measures of past surface salinity preserved in marine sedimentary layers accumulating off the Columbia River mouth, and to place that river discharge variability into the climatologic context of the past ~12,000 years, a time that spans intervals of both warmer and cooler climate than today. By investigating the relationship between climate variability and discharge of this major river system in the past, this research will contribute to a better understanding of what is likely in the future. This project leverages a new suite of sediment cores recently collected via two seagoing research expeditions to the continental slope off the Columbia River, well suited for reconstructions of Holocene climate and river discharge. The sites bracket the offshore Columbia River low salinity plume in its winter and summer extents. The study will analyze fossil plankton shells for oxygen isotopes, barium:calcium and magnesium:calcium ratios, the species abundances of marine foraminiferal plankton and both marine and freshwater diatoms to reconstruct sea-surface temperatures and sea-surface salinity (related to discharge). Analysis of multiple species of known seasonal succession will allow for investigation of seasonality and intermittency of discharge. These data will address a hypothesis that higher temperatures in the NE Pacific are associated with inland drought, relative to an alternate hypothesis that warmer ocean temperature drive higher net precipitation (snow and rain) through an increase in atmospheric moisture. The highly resolved independent chronology of this reconstruction will place PNW hydroclimate and NE Pacific temperature variability into a global temporal framework, improving our understanding of large-scale regional climate dynamics in a part of the world poorly constrained by data and models. Results of this study will advance fundamental understanding of regional-scale dynamic sensitivity of climate and will yield practical knowledge about potential future water supplies of value for long-term planning.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.

干旱还是洪水？哥伦比亚河在多变的全新世气候下流向北太平洋 哥伦比亚河的流量大致反映了太平洋西北地区的供水情况。人们对 20 世纪之前气候变化对供水的长期影响知之甚少，导致目前气候变暖对区域水权、农业生产和渔业的影响存在不确定性。这项研究旨在通过对哥伦比亚河口附近海洋沉积层中保存的过去表面盐度的化学和生物测量来重建河流流量的自然变化，并将河流流量的变化置于过去约 12,000 年的气候背景中，这段时期的气候比今天更温暖和更凉爽。 通过调查过去气候变化与这一主要河流系统流量之间的关系，这项研究将有助于更好地了解未来可能发生的情况。该项目利用了最近通过对哥伦比亚河附近大陆坡的两次航海研究考察收集的一套新的沉积岩芯，非常适合重建全新世气候和河流流量。这些地点将哥伦比亚河近海冬季和夏季的低盐羽流包围起来。该研究将分析化石浮游生物壳的氧同位素、钡：钙和镁：钙比率、海洋有孔虫浮游生物以及海洋和淡水硅藻的物种丰度，以重建海面温度和海面盐度（与排放相关）。对已知季节演替的多个物种进行分析将有助于调查排放的季节性和间歇性。这些数据将解决一个假设，即东北太平洋气温升高与内陆干旱有关，而另一种假设是，海洋温度升高通过大气湿度增加导致净降水量（雪和雨）增加。此次重建的高度解析的独立年表将把西北太平洋水文气候和东北太平洋温度变化纳入全球时间框架，从而提高我们对世界上受数据和模型限制较少的地区的大规模区域气候动态的理解。 这项研究的结果将增进对区域尺度气候动态敏感性的基本了解，并将产生有关未来潜在供水的实用知识，对长期规划有价值。该奖项反映了 NSF 的法定使命，并通过使用评估结果被认为值得支持基金会的智力价值和更广泛的影响审查标准。