2,200-Year tree-ring and lake-sediment based snowpack reconstruction for the northern Rocky Mountains highlights the historic magnitude of recent snow drought

Spruce W. Schoenemann; Justin T. Martin; Gregory T. Pederson; David B. McWethy

doi:10.1016/j.qsa.2020.100013

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2,200-Year tree-ring and lake-sediment based snowpack reconstruction for the northern Rocky Mountains highlights the historic magnitude of recent snow drought

Spruce W. Schoenemann·Justin T. Martin·Gregory T. Pederson·David B. McWethy

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Abstract

In recent decades, Rocky Mountain accumulated snowpack levels have experienced rapid declines, yet long-term records of snowpack prior to the installation of snowpack observation stations in the early and mid 20th century are limited. To date, a small number of tree-ring based reconstructions of April 1 Snow Water Equivalent (SWE) in the northern Rocky Mountains have extended modern records of snowpack variability to ∼1200 C.E. Carbonate isotope lake sediment records, provide an opportunity to further extend tree-ring based reconstructions through the Holocene, providing a millennial-scale temporal record that allows for an evaluation of multi-scale drivers of snowpack variability, from internal climate dynamics to orbital-scale forcings. Here we present a ∼2200 year preliminary reconstruction of northern Rockies snowpack based on δ 18 O measurements of sediment carbonates collected from Foy Lake, Montana. We explore the statistical calibration of lake sediment δ 18 O to an annually resolved snowpack reconstruction from tree rings, and develop an approach to assess and quantify potential sources of error in this reconstruction approach. The sediment-based snowpack reconstruction shows strong low-frequency variability in snowpack over the last two millennia with few snow droughts approaching the magnitude of recent snowpack declines. Given the growing availability of high-resolution, carbonate-rich lake sediment records, such reconstructions could help improve our understanding of how snowpack conditions varied under previous climatic events (mid-Holocene climate optimum ca. 9−6 ka), providing critical insights for anticipating future snowpack conditions.

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Source-reported bounding extent: 40.245991504199026° to 53.38332836757156° latitude; -122.16796875° to -105.3369140625° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Spruce W. Schoenemann, Justin T. Martin, Gregory T. Pederson, David B. McWethy. 2020. 2,200-Year tree-ring and lake-sediment based snowpack reconstruction for the northern Rocky Mountains highlights the historic magnitude of recent snow drought. https://doi.org/10.1016/j.qsa.2020.100013

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