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Characterizing Changes in Eastern U.S. Pollution Events in a Warming World
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  • Arlene M. Fiore,
  • George P. Milly,
  • Laurel Quiñones,
  • Jared Bowden,
  • Sarah E. Hancock,
  • Erik Helstrom,
  • Jean-Francois Lamarque,
  • Jordan Schnell,
  • J. Jason West,
  • Yangyang Xu
Arlene M. Fiore
Lamont-Doherty Earth Observatory of Columbia University

Corresponding Author:[email protected]

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George P. Milly
Lamont-Doherty Earth Observatory of Columbia University
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Laurel Quiñones
Columbia University
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Jared Bowden
North Carolina State University
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Sarah E. Hancock
Columbia University
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Erik Helstrom
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Jean-Francois Lamarque
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Jordan Schnell
Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder NOAA/Global Systems Laboratory
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J. Jason West
University of North Carolina at Chapel Hill
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Yangyang Xu
Texas A&M University
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Risk assessments of air pollution impacts on human health and ecosystems would ideally consider a broad set of climate and emission scenarios and the role of natural internal climate variability within a single scenario. We analyze initial condition chemistry-climate ensembles to gauge the significance of greenhouse-gas-induced air pollution changes relative to internal climate variability, and response differences in two models. To quantify the effects of climate change on the frequency and duration of summertime regional-scale pollution episodes over the Eastern United States (EUS), we apply an Empirical Orthogonal Function (EOF) analysis to a 3-member GFDL-CM3 ensemble with prognostic ozone and aerosols and a 12-member NCAR-CESM1 ensemble with prognostic aerosols under a 21st century RCP8.5 scenario with air pollutant emissions frozen in 2005. Correlations between GFDL-CM3 principal components for ozone, PM2.5 and temperature represent spatiotemporal relationships discerned previously from observational analysis. Over the Northeast region, both models simulate summertime surface temperature increases of over 5 °C from 2006-2025 to 2081-2100 and PM2.5 of up to 1-4 μg m-3. The ensemble average decadal incidence of upper quartile Northeast PM2.5 events lasting at least five days doubles in GFDL-CM3 and increases >50% in NCAR-CESM1. In other EUS regions, inter-model differences in PM2.5 responses to climate change cannot be explained by internal climate variability. Our EOF-based approach anticipates future opportunities to data-mine initial condition chemistry-climate model ensembles for probabilistic assessments of changing frequency and duration of regional-scale pollution and heat events while obviating the need to bias-correct concentration-based thresholds separately in individual models.
16 May 2022Published in Journal of Geophysical Research: Atmospheres volume 127 issue 9. 10.1029/2021JD035985