Collaborative Research: RUI: Glacier resilience during the Holocene and late Pleistocene in northern California

冰川是下游社区的重要水资源，也是气候变化的敏感记录者。重建的冰川在最后一个冰河时期的位置被用来推断美国西部过去的气候变化。然而，以前的研究主要集中在大陆内部（如落基山脉）或内华达山脉。该项目通过重建过去的冰川变化，研究了加利福尼亚北部克拉马斯山脉三一阿尔卑斯地区过去2万年的气候变化。这项研究首次提供了来自太平洋近端克拉马斯山脉（Klamath Mountains）的冰川作用的定量数据，该地区的气候可能与内陆大陆山脉不一致。这项研究正在重建加州北部过去的气候，填补了美国西部冰川历史的空白。该项目强调了气候变化对加州北部冰川的影响，以及对加州和全球水资源的社会影响。其他项目目标还包括作为激励和招募地球科学本科专业学生的催化剂，并为地质和环境科学家的职业发展铺平道路。所有项目机构均为少数民族服务机构或西班牙裔服务机构；该项目为32名学生提供了为期一周的实地考察机会，重点关注中央山谷水项目和加州的水资源。通过将来自该州最北端和最南端的不同学生聚集在一起，这次实地考察的目的是激发学生对地球科学的兴趣，扩大他们的视野，并促进这些未来领导者之间的合作。此外，13名本科生和3名研究生被支持进行研究并在会议上展示他们的发现。本项目采用多学科方法识别北加州三位一体阿尔卑斯地区过去的气候变化，并通过整合地貌测绘、10Be地表暴露年代测定、湖泊沉积物岩心、树木年代学/树木气候学以及冰川和气候变化的数值模拟来评估这些变化的机制。在最近消亡之前，三一阿尔卑斯山脉的冰川是美国大陆海拔最低的冰川之一。这些冰川比落基山脉和内华达山脉的冰川更接近太平洋的湿气来源。因此，在过去的2万年里，三一阿尔卑斯山脉的冰川对气候变化的反应可能与美国大陆的干旱地区不同。通过将该项目的气候重建结果与PMIP4/CMIP6的古气候全球气候模式和先前发表的古气候记录的输出结果进行比较，评估了这些过去气候变化的机制。通过使用多学科的方法，该项目为北加州提供了一个新的冰川和气候历史，并评估了与这些变化相关的机制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Glaciers are important water resources for downstream communities and are sensitive recorders of climate change. The reconstructed position of glaciers through the last ice age has been used to infer past climate changes in the western U.S. However, previous research has focused along the continental interior (e.g., the Rocky Mountains) or the Sierra Nevada. This project investigates climate changes over the past 20,000 years in the Trinity Alps region of the Klamath Mountains, northern California by reconstructing past glacier changes. The study provides the first quantitative data on glaciation from the Pacific-proximal Klamath Mountains, a location that may be out-of-phase climatically with interior continental ranges. The research is producing new reconstructions of past climate for northern California and fills a spatial gap in the glacial history along the western United States. The project highlights the impact of climate change on glaciers in northern California, with societal impacts for water resources in California and globally. Additional project goals include acting as a catalyst to inspire and recruit geoscience undergraduate majors and develop pathways for careers as geological and environmental scientists. All project institutions are Minority-Serving or Hispanic-Serving Institutions; the project provides 32 students an opportunity for a one-week field trip focusing on the Central Valley Water Project and water resources in California. By bringing together diverse students from the northernmost and southernmost parts of the state, the aim of this field trip is to stimulate the students’ interest in geoscience, expand their perspectives, and foster collaboration within these future leaders. Additionally, thirteen undergraduate and three graduate students are supported to conduct research and present their findings at conferences. This project uses a multi-disciplinary approach to identify past climate changes in the Trinity Alps of northern California and to evaluate the mechanisms for these changes by integrating geomorphic mapping, 10Be surface exposure dating, lake sediment coring, dendrochronology/dendroclimatology and numerical modeling of glaciers and climate changes. Until their recent demise, glaciers in the Trinity Alps were some of the lowest-elevation glaciers in the continental United States. These glaciers are closer to the moisture source of the Pacific Ocean than the better-studied glaciers in the Rocky Mountains and Sierra Nevada. Thus, glaciers in the Trinity Alps may have responded differently to climate changes over the past 20,000 years than the drier regions in the continental United States. The mechanisms for these past climate changes are being evaluated by comparing the climate reconstructions from this project to output from paleoclimate global climate models from PMIP4/CMIP6 and previously published paleoclimate records. By using methods from multiple disciplines, this project provides a new glacial and climate history for northern California and evaluates of the mechanisms associated with these changes.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.