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

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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.