A Chemical History of Anthropogenic Input to the Atmosphere throughout the Industrial Era

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This project will develop a history of anthropogenic emissions of short-lived pollutants to the atmosphere during the period from 1850 to 2010. It will produce estimate of all major aerosol species, aerosol precursors, short-lived trace gases, ozone precursors, and major trace elements emitted from anthropogenic, energy-related combustion and industrial processes for that period. This work represents the first attempt at constraining histories of these species by integrating all available records, from engineering histories to ice cores. Trends in technology change and emission were previously developed on the basis of engineering records and used to estimate black and organic carbon histories. Process-specific emissions of other tracers will be added to develop a time history of multiple tracers. Emissions will be translated to atmospheric concentrations and deposition using the Community Atmosphere Model (CAM) developed at the National Center for Atmospheric Research. Measured histories of deposition will be tabulated as recorded in lake sediments and ice cores. This project will update the CAM deposition parameterization, particularly for snow and ice, based on recent polar campaigns. It will also conduct an analysis of transport to and deposition in remote regions by climate mode, using a 40-year run with prescribed meteorology, to assess transport and deposition prior to 1960. A scheme will be developed to obtain an optimal representation of emitting technology by comparison with predicted and observed deposition records. Trends, rather than absolute magnitudes, will be the primary basis for comparison. Markers used for optimization will include elemental ratios in source profiles and differences in observations near and far from sources. The optimized technology base will then provide emissions of the important atmospheric species. The broader impacts of this project include: (i) spatially and temporally resolved inputs to global chemical and transport models that evaluate changes in climate forcing, transient climate response, and climate sensitivities from short-lived chemical species and (ii) critical inputs to models of time-dependent anthropogenic perturbations to biogeochemical cycles. A graduate student and two undergraduate students will participate in this project