Changes in Climate, Pollutant Emissions, and US Air Quality: An Integrating Modeling Study

EPA Grant Number: R833374
Title: Changes in Climate, Pollutant Emissions, and US Air Quality: An Integrating Modeling Study
Investigators: Adams, Peter , Pandis, Spyros N.
Institution: Carnegie Mellon University
EPA Project Officer: Ilacqua, Vito
Project Period: March 1, 2007 through February 28, 2011 (Extended to February 28, 2012)
Project Amount: $896,596
RFA: Consequences of Global Change For Air Quality (2006) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Climate Change , Air


Future changes in climate, biogenic emissions, and long-range transport of pollution may provide additional challenges to air quality management in the U.S. The goal of this study is to quantify the expected magnitude and range of these impacts on ozone, PM2.5, PM2.5-10, and ultrafine PM concentrations, visibility, mercury and acid deposition. The study will cover the whole country with emphasis in the Northeast, South, and Southwest U.S. The impacts on both air pollution episodes and annual average conditions will be investigated.


The recently developed and evaluated CMU Global-Regional Climate Air Pollution Modeling Systems (GRE-CAPS) will be extended and applied for the purposes of the study. This modeling system currently combines the GISS global climate and chemical transport model (GISS GCM/CTM), with the regional meteorological model MM5 and the multiscale regional CTM PMCAMx. The modeling system describes atmospheric chemistry and dynamics at four scales: global (4x5 degrees), continental (36x36 km), regional (12x12 km), and urban (4x4 km). Currently predicted variables include the concentrations of ozone and its precursors, the aerosol size/composition distribution, acid deposition fluxes, and visibility. The modeling system will be extended to include: (a) an emissions processing system that accounts for climate-sensitive emissions (e.g. biogenic, ammonia, evaporative emissions, etc.), (b) a new organic aerosol module accounting for recent developments in understanding of the formation and partitioning of secondary organic aerosol and the volatility of primary organic aerosol components, (c) a mercury atmospheric chemistry and deposition module, and (d) a description of the ultrafine aerosol size-composition distribution. The global and regional CTMs will use the “relative-smart” aerosol, aqueous-phase, and gas-phase chemistry modules developed by our group to maximize computational efficiency without sacrificing accuracy.

The extended modeling system will be evaluated for the present-day against existing data from various networks (STN, IMPROVE, MDN, etc.) and the EPA Supersites. A new approach for future climate scenario screening and selection for regional air quality simulations is proposed. We will screen and ensemble of approximately 30 years of future climate (nominal year 2050) generated with the GIXX GCM to select both “representative” years but also more extreme (colder-warmer, wetter-drier, clearer-cloudier) years for uncertainty analysis. The GRE-CAPS simulations for 2050 with and without climate change will be used for the investibation of the climate change effect on U.S. air quality. A range of sensitivity simulations (turning off the climate sensitivity of emissions and/or changes in long range transport) will allow us to quantify the impact of the change in emissions due to climate and the long-range transport of pollution to the overall air quality change. This analysis will be extended with a set of alternative future scenarios to explore uncertainties associated with future emissions and a test where the location of sources will be changed.

Expected Results:

Ultimately, this research will provide both the insights and the tools to inform air quality management decisions about the impacts of global climate and emission changes on U.S. quality.

Publications and Presentations:

Publications have been submitted on this project: View all 29 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 21 journal articles for this project

Supplemental Keywords:

air quality modeling, smog, PM, general circulation models,, RFA, Scientific Discipline, Air, climate change, Air Pollution Effects, Environmental Monitoring, Atmospheric Sciences, Ecological Risk Assessment, Atmosphere, air quality modeling, particulate matter, atmospheric models

Progress and Final Reports:

  • 2007 Progress Report
  • 2008 Progress Report
  • 2009
  • 2010 Progress Report
  • Final Report