EAS Fall 2017 Seminar Speaker: Dr. Sarah Aarons, University of Michigan
Dust in the atmosphere has a significant effect on earth’s climate by scattering or absorbing incoming solar radiation, acting as cloud condensation nuclei, or providing critical nutrients to oceans and terrestrial biospheres. Variations in the provenance and flux of dust from source areas to a particular location can be an indicator of changes in production, sources, and atmospheric transport pathways through time as a function of climate change. These observed changes have implications for understanding the interactions between atmospheric aerosols, global climate, and biogeochemical cycles.
The research presented here characterizes dust transported in the atmosphere and deposited on the Taylor Glacier, Antarctica, providing information about dust source regions (provenance), the amount of material available for uptake into the atmosphere (aridity and land cover), and the dominant wind direction.
Radiogenic isotopes serve as a chemical “fingerprint” of dust, and identify the changes in provenance throughout time. This ice-core record from the Taylor Glacier shows significant differences in dust composition from the Last Glacial Period to the Holocene, and the comparison of two interglacial periods reveals large discrepancies in dust sources during the penultimate interglacial (MIS 5e) and the Holocene. The profound change in composition suggests a variation in atmospheric transport pathways and/or paleo-environmental conditions between the interglacial periods, and indicates that MIS 5e should be reassessed as an analog for current climate change.