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

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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.