a. Non-technical explanation of the project's broader significance and importance
Human influences on climate are global, such as through atmospheric greenhouse gases, and also regional, from dust that spreads from soil disturbance. Increased human activity such as agriculture and livestock grazing in the American southwest and the Colorado Plateau during the past several decades has been correlated with greater dust production and deposition. Changes in dust production on a seasonal to annual basis can be seen in the amount incorporated into mountain snow and these changes are preserved in the ice of alpine glaciers that span the last several hundred years. Variations in the origin of dust particles reaching an ice sheet or glacier can indicate a shift in dust production, sources, and atmospheric transport pathways, and are therefore valuable indicators of land use and climate change. This project will examine a semi-continuous record of North American dust in an ice core from the Upper Fremont Glacier (Wind River Range, Wyoming). This ice core spans the Agricultural and Industrial Revolution and will assess how changing land use, climate and weather in the western United States from the end of the Little Ice Age (1350-1850 AD) to today is recorded by dust compositional changes.
b. A technical description of the project
This research will evaluate the change in atmospheric dust levels due to anthropogenic activities using ice from the Upper Fremont Glacier in the Wind River Range, Wyoming. The primary objective of this research is to measure the physical and chemical characteristics of aerosol mineral dust in order to construct a record of dust load and provenance variability in the American West from the end of the Little Ice Age through the Industrial Revolution and into the dramatic expansion of agriculture across the United States. An existing ice core from the Upper Fremont Glacier will be used to measure variations in the dust amount. Grain size, trace element concentration, and radiogenic isotopic compositions (Sr, Nd, Hf) will also be determined. Potential sources of the dust in North America will be collected from spatially distributed sites and chemically characterized. The data from the ice core and field-collected source areas will be compared to determine the variations in dust amounts and sources, and to examine the relationship to regional climate and land-use changes.
