Projecting Wildfire Emissions and Their Air Quality Impacts in the Southeastern U.S. from 2010 to Mid-century

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  • July 24, 2019
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  • Shankar, Uma
    • Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
Abstract
  • Wildfires can severely impair the health of ecosystems, life forms and regional economies. In the rapidly changing U. S. Southeast, both climate and socioeconomic factors (e.g., population and income) drive wildfires, and need to be represented in wildfire inventories to assess the air quality (AQ) impacts and health risks of wildfires long-term. This motivated the development of a wildfire emissions projection methodology leveraging published models of annual areas burned (AAB) based on county-level socioeconomic and climate projections for 2011-2060. It is applied to project two sets of AAB with different climate downscaling approaches, to estimate wildfire emissions for 2010 and four mid-century years. These are compared with emissions estimated using 18-year historical mean AAB without changes in climate and socioeconomics. Competing climate and socioeconomic factors result in 7% - 32% lower projected AAB than historical values, and 13% - 62% lower fine particulate matter (PM2.5) emissions than estimated from historical AAB in the selected years, with climate driving their temporal variability. Evaluation of the emissions projection methods in air quality (AQ) simulations against those using the National Emissions Inventory (NEI), and network observations for 2010 show little difference among the methods in ozone (0.08% - 0.93%) and PM2.5 (1% - 8%). Larger, comparable biases relative to observations in all three methods for secondary species, especially in winter, are attributable to non-wildfire emissions or secondary chemical production. The projection methods predict primary wildfire PM better than the NEI, providing confidence that they can assess current wildfire AQ impacts, while enabling longer-term AQ assessments unachievable with static inventories. AQ simulations using the projected wildfire emissions, and projected emission reductions in SOx and NOx from energy and transportation (by ~80% at mid-century) show peak periods and locations of wildfire impacts on ozone and PM shifting from autumn in Midwestern locations in 2010, to warmer and drier summers east and south by mid-century, following the AAB spatiotemporal patterns. Although considerably lower than 2010 levels, summertime PM2.5 increases by 4%-5% in 2040-2060 in this emission scenario, driven by increases in OC and unspeciated other PM.
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Advisor
  • Binkowski, Francis S.
  • West, James J.
  • Prestemon, Jeffrey P.
  • Leith, David
  • Vizuete, William G.
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2019

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