Oxygen isotope records of climate change are used to quantify past climatic conditions, to identify mechanisms of past climatic variability, to verify model simulations of past climate. This research will develop a high-resolution isotopic record of climate change in northwestern Nevada over the past 4000 years. Sediment cores recovered from Big Soda Lake near Fallon, Nevada are seasonally laminated which make it possible to reconstruct a detailed high-resolution record (i.e. sub-decadal) of Holocene climate change in the western part of the Great Basin. The lake is primarily fed by groundwater; therefore, changes in the fauna, mineralogy and geochemistry are directly related to changes in climate and human activity. A key question is to what extent prehistoric changes in groundwater levels compare to those recorded during recent historical times. Sedimentary characteristics such as geochemistry, grain size, magnetic susceptibility, and organic content will be measured to identify regional changes in climate. Accurate chronological control will be ensured through multiple methods including varve (sediment layer) counting, radiocarbon dates on pollen concentrations, dated tephras, non-native pollen and lead-210 dating. This research will contribute to our current understanding of climate change in through creation of continuous sediment core records that fill important gaps from previous research.

This sub decadal-resolution study will resolve temporal gaps in our understanding of the regional variation of past climate change, and resolve chronological problems that have hindered previous lake studies in the region. The results will provide insight into the variability of late Holocene climate change in the western Great Basin. Understanding past climate change in this drylands region with an expanding population, can help predict potential future change where natural and human activities are sensitive to changes in the water balance.

As a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising student to establish a strong independent research career.

Project Report

Laminated sediments from Big Soda Lake provide a rare opportunity to reconstruct a detailed high-resolution record (i.e. sub-decadal) of Holocene climate change in the western part of the Great Basin. The seasonally laminated Big Soda?lake sediments are unique when compared to other late Holocene records of climate change from the Great Basin, inferred from tree rings or lake levels that have surface water inputs. The lake is only fed by groundwater and therefore changes in the fauna, mineralogy and geochemistry are directly related to changes in climate that are also related to groundwater levels. This research provided a firm chronology of climate change events during the past 5,000 years using a wide range of analytical techniques: pollen, stable isotope, tephra, and geochemical. Chronological control was provided by lead-210, conventional AMS dating and identified tephras. which will facilitated comparison with other paleoclimate studies. This research allowed us to firm up knowledge of climate change on the west side of the Great Basin, especially for the mid-to Late Holocene. Big Soda Lake is in a transition zone between Pyramid and Mono lakes aswell as Walker Lake to the south. The results of this study help tie together the history of climate change in the region. An understanding of how climate in Nevada responds to global and regional forcing mechanisms on short timescales provide help for the management of scarce water resources and also provide a basis for predicting how natural patterns will interact with future climate warming. The records generated complement and expand on related datasets from lakes in Nevada and California, thereby revealing spatial and temporal changes in the water cycle. The findings also benefit ongoing research in Great Basin paleoecology, and archaeology by providing a high-resolution record of Holocene climate change. Broader Impacts of the Research Benefits to society-This investigation was undertaken to develop a high-resolution record of climate change during the Holocene. Dissemination of results-The results will be disseminated widely to the scientific community through publication, presentations at the annual meetings of major scientific societies, (e.g. AAG, AGU, PACLIM). Given the great potential sensitivity of water resources in the study area to future climate change, the research is socially relevant and may be expected to impact future water policy decisions. Promoting teaching, learning, and public outreach-Data collected during this research project will be soon disseminated to the local community in Fallon and other agencies in the area (e.g. Churchill County Parks). The results of the research will be presented at a workshop and public meeting at the Churchill County Museum in Fallon. An informational workshop on the environmental history of Fallon area is also planned for members of the Northern Paiute native peoples group, whose ancestral lands included the area around Big Soda Lake.

National Science Foundation (NSF)
Division of Behavioral and Cognitive Sciences (BCS)
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Thomas J. Baerwald
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University of California Berkeley
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