Loretta Mickley's Research Page


The overarching goal of my research is to understand how the short-lived chemical species in the atmosphere -- mainly tropospheric ozone and aerosol -- interact with climate on global and regional scales. I use global models of climate and atmospheric chemistry together with observations from the recent and distant past.

CURRENT PROJECTS

  • Effects of climate change on air quality
  • Effects of climate change on wildfires
  • Effects of land cover change on chemistry-climate interactions
  • Climate impacts of trends in U.S. aerosols
  • Oxidation capacity of the atmosphere during the Last Glacial Maximum

    For information on Past Projects, go here.

    Effects of climate change on air quality

    BACKGROUND:

    Weather is a major factor affecting air pollution, and it follows that climate change could have significant implications for air pollution control strategies. We lead a multi-institutional project (GCAP) to explore the effects of future changes in climate and global emissions on air quality in the United States and elsewhere. The work involves analysis of air pollution meteorology in the NASA/GISS general circulation model for present and future climate, interface with the GEOS-Chem chemical transport model for global simulations of future atmospheric composition, and downscaling to the regional scale with the EPA/CMAQ air pollution model. We also use correlation statistics of air pollution variables with meteorological variables for present-day climate to draw inferences on the effects of climate change. Our focus is on ozone and particulate matter air pollution as well as on mercury deposition and accumulation in ecosystems.

    OBJECTIVES:

    • Examine long-term trends in air pollution meteorology driven by climate change;
    • Determine the effects of expected 2000-2050 climate change on surface air quality and mercury deposition in the United States and worldwide, independent of changes in anthropogenic emissions;
    • Determine the combined effects of 2000-2050 changes in climate and global anthropogenic emissions on air quality;
    • Examine how climate change will affect the intercontinental transport of pollution.

    APPROACH:

    • Conduct transient 1950-2050 climate change simulations with the GISS GCM, diagnose trends in air pollution meteorology, including in particular mid-latitude cyclone frequency, and compare to available climatology;
    • Use the GEOS-Chem chemical transport model coupled to the GISS GCM to examine trends in ozone, particulate matter, and mercury;
    • Interface the GISS/GEOS-Chem global modeling system with the CMAQ regional model for local diagnostic of future air pollution levels;
    • Examine correlations of air pollution levels with meteorological variables for present-day climate.

    COLLABORATORS: Daniel Jacob, Eric Leibensperger, Moeko Yoshitomi, Amos Tai, Shiliang Wu (Michigan Tech), Daewon Byun (U. Houston), Joshua Fu (U. Tenn), David Rind (GISS), John Seinfeld (Caltech), Havala Pye (Caltech), David Streets (Argonne), Ruby Leung (PNL), and Alice Gilliland (EPA/ORD).

    REFERENCES:

    • Mickley, L.J., D.J. Jacob, B.D. Field, and D. Rind, Effects of future climate change on regional air pollution episodes in the United States, Geophys. Res. Let., 30, L24103, doi:10.1029/2004GL021216, 2004. [Abstract] [(pdf)]

    • Spring 2005: Loretta Mickley is in the news for her AAAS talk on climate change and air quality.

    • Wu, S., L.J. Mickley, Eric M. Leibensperger, D.J. Jacob, D. Rind, and D. G. Streets, Effects of 2000-2050 global change on ozone air quality in the United States, J. Geophys. Res., 113, D06302, doi:10.1029/2007JD008917, 2008. [(pdf)]

    • Leibensperger, E. M., L. J. Mickley, D. J. Jacob, Sensitivity of U.S. air quality to mid-latitude cyclone frequency and implications of 1980-2006 climate change, Atmos. Chem. Phys., 8, 7075-7086, 2008. (pdf)

    • GCAP home page

    SUPPORT: EPA, EPRI

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    Effects of changing climate on fires

    BACKGROUND:

    The occurrence and intensity of wildfires is strongly related to climate. Fires may be more common in a future warmer climate as rainfall patterns change. We are investigating the consequences of climate change on wildfires, and the impact on U.S. air quality.

    OBJECTIVES:

    • Quantify the effect of present day fires on air quality in the United States;
    • Explore the relationship between climate and the frequency and magnitude of wildfires in North America, and develop scenarios for future fires;
    • Examine how different scenarios for future fires will affect air quality in a future climate;
    • Examine the trade-offs in air pollutant emissions between managed fires and catastrophic fires.

    APPROACH:

    • Determine the best predictors for area burned for different ecosystems, using the Fire Weather Index system or the Fire Weather Danger Rating System
    • Conduct GISS general circulation model simulations of future climate change including tracers of wildfire pollution;
    • Perform global coupled ozone-aerosol simulations for the present day and future climates using the GEOS-Chem model driven by meteorological and area burned statistics from the GCM;
    • Perform CMAQ simulations of selected future years for more accurate prediction of the effects.

    COLLABORATORS: Jennifer Logan, Daewon Byun (University of Houston), David Diner, Qinbin Li, Dominic M. Mazzoni (Jet Propulsion Laboratory), Rynda Hudman (U.C. Berkeley), and Dominick Spracklen (University of Leeds)

    REFERENCES:

    • Summer 2009: Dominick Spracklen, Jennifer Logan, and Loretta Mickley are in the news for their wildfire work.

    • Spracklen, D. V., L. J. Mickley, J. A. Logan. R. C. Hudman, R. Yevich, M. D. Flannigan, and A. L. Westerling, Impacts of climate change from 2000 to 2050 on wildfire activity and carbonaceous aerosol concentrations in the western United States, J. Geophys. Res., doi:10.1029/2008JD010966, 2009. (pdf)

    • Spracklen, D. V., J. A. Logan, L. J. Mickley, R. J. Park, R. Yevich, A. L. Westerling, and D. Jaffe, Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer., Geophys. Res. Let. 34, L16816, doi:10.0129/GL030037, 2007. (pdf)

    SUPPORT: EPA

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    Climate impacts of trends in U.S. aerosols

    BACKGROUND:

    Aerosols have a cooling effect on climate by scattering solar radiation to space and increasing the reflectivity of clouds. At the same time, they represent a major component of air pollution, clearly linked to human mortality and acid rain. Aerosol sources in the U.S. are increasingly controlled to address these pollution concerns, but what will be the consequence for climate change? We need to understand whether removal of this cooling umbrella could expose us to the full brunt of greenhouse warming.

    OBJECTIVES:

    • Understand the roles of anthropogenic U.S. sources of aerosols on climate change in the U.S. and globally, over the past several decades and projecting into the future.

    APPROACH:

    • Construct historical reconstructions and future projections of aerosol concentrations over the U.S. and downwind using the GEOS-Chem model.
    • Simulate 1950-2050 climate with the GISS GCM driven by historical and future aerosol concentrations.

    COLLABORATORS: Eric Leibensperger, Daniel Jacob, David Rind (GISS), and John Seinfeld (Caltech)

    SUPPORT: EPRI

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    Effects of land cover change on chemistry-climate interactions

    BACKGROUND:

    Land cover change can have large impacts on the concentrations of aerosols and tropospheric ozone, with consequences for air quality and climate change. For example, biogenic emissions are important sources of ozone and aerosol precursors. Dust is more easily mobilized from dry regions with little vegetation. Deforestation may lead to regional meteorological changes (e.g., decreased humidity and increased surface winds), enhancing the frequency of forest fires, which in turn emit ozone precursors, carbonaceous aerosol, and ammonia. We are presently investigating these effects of land cover changes on atmospheric composition, the implications for climate change, and the feedbacks on land cover.

    OBJECTIVES:

    • Predict the impact of future land cover change on atmospheric composition;
    • Investigate the climate response.

    APPROACH:

    • Perform 2000-2100 GCM climate simulations, with present-day vegetation maps and with vegetation maps calculated by the LPJ and Hyland models for future conditions;
    • Perform 5-year GEOS-CHEM simulations at 25-year intervals, from 2000 to 2100, with present-day vegetation and GCM control meteorology and with changing vegetation and the corresponding GCM meteorology;
    • Validate model vegetation maps for the present-day with data from the MODIS satellite instrument.

    COLLABORATORS: Amos Tai, Jed Kaplan (ISPRA), David Rind (NASA/GISS), and Shiliang Wu (Michigan Tech)

    SUPPORT: NASA

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    Oxidation capacity of the atmosphere during the Last Glacial Maximum

    BACKGROUND:

    The hydroxyl radical (OH) plays a major role in determining the lifetimes of atmospheric trace gases important to climate change and human health. Knowledge of OH concentrations in past atmospheres remains elusive due to the lack of a geological proxy for paleo oxidant concentrations. We are testing a novel proxy of paleo oxidant concentrations, the oxygen isotopic composition in sulfate aerosol deposited in ice cores. The oxygen isotopic composition in a sulfate particle is determined by which oxidation pathway (via OH, ozone, or hydrogen peroxide) led to its formation. This isotopic composition is preserved throughout the ice core record.

    OBJECTIVES:

    • Test the hypothesis that the oxygen isotopic composition of sulfate in ice cores can provide quantitative information on atmospheric oxidant concentrations in past climates.
    • Use the oxygen isotope information in sulfate to better understand the methane budget of the Last Glacial Maximum.

    COLLABORATORS: Becky Alexander (PI, University of Washington), Eric Sofen, and Lee Murray.

    SUPPORT: NSF

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    For Loretta's cv, click here. For information on Past Projects, go here.

    For a slightly less technical powerpoint presentation on climate change, click here.

    Back to Loretta's homepage.

    Back to Atmospheric Chemistry Modeling Group webpage.