Doctoral Dissertation Research: A Long-Term Paleoclimate Perspective on the Changing Hydroclimatology of the Bear River Basin

沉积档案中的古气候记录提供了关于一个地区自然气候长期变化范围的基线信息。熊河盆地位于犹他州、爱达荷州和怀俄明州的交汇处，是为三个州提供水资源的重要地区。未来该流域和瓦萨奇沿岸的人口增长将越来越依赖于未来几年的水资源供应。由于相对较短的工具数据集，熊河水资源的长期变化尚未得到很好的理解，但资源管理者和政策制定者需要从长远的角度来规划未来的发展，以避免在未来造成政治冲突或危及附近候鸟保护区等地区敏感的野生动物栖息地。从贝尔河山脉的湖泊沉积物和洞穴中提取的古气候数据，将为贝尔河流域的水文气候和植被提供急需的长期记录。从一个小冰湖收集的沉积物岩心中提取花粉、木炭、磁化率和着火损失数据。这些数据将提供该地区近13000年来的气候和植被记录。在Minnetonka洞穴附近的石笋中，稳定的碳氧同位素比值也将被用于发展一个独立的气候和植被历史，以几十年的分辨率。洞穴记录和湖泊记录都被频繁地用于提取世界各地的古气候代理数据。然而，由于记录之间的距离相对较大，或者地形环境明显不同，直接比较从两个档案中获得的记录往往是困难的。这项研究将比较相距不到10公里的洞穴记录和湖泊记录。此外，洞穴和湖泊位于相似的海拔高度，都位于主山脊东侧的山谷中。因此，可以假定这两个地点的条件在重叠记录的整个长度上是相似的，从而可以直接比较档案的敏感性。该项目的结果将为了解历史上的熊河水资源清单提供背景。此外，由于熊河山脉位于观测到的区域气候边界上，该地区的古气候记录将提供过去边界迁移及其对当地水文气候条件和生物地理的影响的长期记录。将熊河流域过去气候变化的时间和性质与南北地区进行比较和对比，将有助于细化由于全球气候变化而预测未来降水增加/减少的地区的空间分布。该研究还将为古气候学领域提供方法上的贡献，为湖泊和洞穴沉积记录中可能存在的任何信号保存偏差提供见解。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

Paleoclimate records from sedimentary archives provide baseline information about the long-term range of natural climate variability in a region. The Bear River Basin, located at the intersection of Utah, Idaho, and Wyoming, is an important area providing water resources for three states. Future population growth in the basin and along the Wasatch Front is going to increasingly depend on the availability of water in coming years. Long-term variability in Bear River water resources is not well understood due to relatively short instrumental datasets, yet resource managers and policy makers will need a long-term perspective to plan future development to avoid creating future political conflicts or endangering sensitive wildlife habitat in areas such as a nearby migratory bird refuge. Paleoclimate data extracted from lake sediments and speleothems from the Bear River Range, a primary hydrologic recharge area for the Bear River, will provide a much needed long-term record of hydroclimate and vegetation in the river basin. Pollen, charcoal, magnetic susceptibility, and loss-on-ignition data will be extracted from sediment cores collected from a small glacial lake. These data will provide a record of climate and vegetation in the area over approximately the last 13,000 years. Stable carbon and oxygen isotope ratios from a stalagmite in nearby Minnetonka Cave will also be used to develop an independent climate and vegetation history at multi-decadal resolution. Speleothem records and lacustrine records have both been used frequently to extract paleoclimate proxy data from locations throughout the world. However, a direct comparison of records obtained from the two archives is often difficult due to relatively large distances between records, or significantly different topographic settings. This study will compare a speleothem record and a lake record located less than 10km from one another. Furthermore, the cave and the lake are located at similar elevations and both lie in valleys located on the east side of the main ridgeline. Thus, conditions at the two sites can be assumed to have been similar throughout the length of the overlapping records, allowing a direct comparison of archive sensitivity.The results of this project will provide context for understanding historic Bear River water resource inventories. In addition, due to the location of the Bear River range along an observed regional climate boundary, the paleoclimate record from the region will provide a long-term record of past boundary migration and the resultant effects on local hydroclimatic conditions and biogeography. Comparing and contrasting the timing and nature of past climate changes in the Bear River Basin with locales to the north and south will help refine the spatial distribution of areas that are predicted to have increased/ decreased precipitation in the future, as a result of global climate change. This study will also provide a methodological contribution to the field of paleoclimatology by providing insights into any signal preservation biases that may exist in lake and cave deposit records. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.