Congratulations to Sarah Aarons who successfully defended her dissertation on February 8, 2016.

Advisors: Joel D. Blum and Sarah Aciego

Abstract: Dust in the atmosphere has a significant effect on earth’s climate by scattering or absorption of incoming solar radiation, acting as cloud condensation nuclei, or providing critical nutrients to oceans and terrestrial biospheres. Changes in the locations of dust source areas and pathways can provide insight into understanding the relationship between mineral dust, global climate, and biogeochemical cycles. To gain a better understanding of the impact of the dust cycle on global and regional climate, the dust records within ice-cores from three locations are utilized to reconstruct changes in atmospheric circulation and dust provenance using radiogenic isotope data, trace and rare earth element composition, anion concentration, dust concentration, and size distribution. In this dissertation thesis, we applied this methodology to investigate three case studies. Ice-core samples from the Upper Fremont Glacier (UFG) in Wyoming, Taylor Dome, an East Antarctic ice-dome, and Taylor Glacier, the outlet glacier for Taylor Dome, are investigated here. In the UFG, we found that samples reveal anthropogenic influences. Variability in dust sources and pathways indicates a transition from far to near-range transport due to land-use changes associated with agricultural activity and livestock grazing expansion during 1700 – 1975 A.D. Samples from Taylor Dome and Taylor Glacier, spanning the time period 1,800 – 55,000 years before present, indicate a shift from long-range transported dust to a more variable local input during the transition out of the last glacial period when global temperatures rose 4-7 degrees C. Dust sources and transport pathway changes reveal atmospheric circulation restructuring following the last climatic transition and subsequent retreat of the Ross Ice Shelf.