Loretta Mickley: Research

The goal of our research is to understand how short-lived chemical species in the atmosphere, including tropospheric ozone and aerosol, interact with climate on global and regional scales. We use global models of climate and atmospheric chemistry together with observations from the recent and distant past. We also build statistical models to quantify observed relationships between meteorological variables and air quality. (Back to Loretta's homepage.)

Current areas of research
  • Effects of aerosol trends on regional climate

  • Climate impacts on air quality

  • Influence of climate on atmospheric oxidative capacity

  • Wildfires and agricultural fires: Links with atmospheric chemistry

  • Consequences of changing air quality for human health

  • Recent trends in key atmospheric species

  • Effects of aerosol trends on regional climate

    Background:
    Aerosols influence regional climate through their interactions with incoming solar radiation and with clouds. Aerosols are also known as particulate matter and represent a major component of air pollution. In recent decades U.S. enviromental policies have led to large cuts in aerosol sources, but the consequences for regional climate are not clear. At the same time, aerosol loading in Asia has increased dramatically as rapid industrialization takes place there. The climate impacts of these disparate trends in anthropogenic emissions for remote regions such as the Arctic are unknown.

    Key questions:
  • Can we explain the observed U.S. "warming hole" of the 1980s with trends in aerosol sources?
  • Do trends in aerosols influence regional hydrology, including drought risk?
  • What role does changing aerosol have in the observed rapid warming over the Arctic?
  • What are the climate consequences of increasing aerosol over China?
  • People: Cusworth, Leibensperger, Moch.

    References:
  • Breider, T.J., L.J. Mickley, D.J. Jacob, C. Ge, J. Wang, M.P. Sulprizio, B. Croft, D.A. Ridley, J.R. McConnell, S. Sharma, L. Husain, V.A. Dutkiewicz, K. Eleftheriadis, H. Skov, and P.K. Hopke, Multi-decadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980, J. Geophys. Res., 122, 3573-3594, 2017. (pdf)
  • Breider, T.J., L.J. Mickley, D.J. Jacob, Q. Wang, J.A. Fisher, R.Y.-W. Chang, and B. Alexander, Annual distributions and sources of Arctic aerosol components, aerosol optical depth, and aerosol absorption, J. Geophys. Res. Atmos., 119, 4107-4124, 2014. (pdf)
  • Cusworth, D.H., L.J. Mickley, E.M. Leibensperger, and M.J. Iacono, Aerosol trends as a potential driver of regional climate in the central United States: Evidence from observations, Atmos. Chem. Phys. Disc., in review. (pdf, sup)
  • Leibensperger, E.M., L.J. Mickley, D.J. Jacob, W.-T. Chen, J.H. Seinfeld, A. Nenes, P.J. Adams, D.G. Streets, N. Kumar, D. Rind, Climatic effects of 1950-2050 changes in US anthropogenic aerosols - Part 1: Aerosol trends and radiative forcing, Atmos. Chem. Phys., 12, 3333-3348, 2012. (pdf)
  • Leibensperger, E.M., L.J. Mickley, D.J. Jacob, W.-T. Chen, J.H. Seinfeld, A. Nenes, P.J. Adams, D.G. Streets, N. Kumar, D. Rind, Climatic effects of 1950-2050 changes in US anthropogenic aerosols - Part 2: Climate response, Atmos. Chem. Phys., 12, 3349-3362, 2012. (pdf)
  • Mickley, L.J., E.M. Leibensperger, D.J. Jacob, and D. Rind, Regional warming from aerosol removal over the United States: Results from a transient 2010-2050 climate simulation, Atmos. Env., 46, 545-553, 2012. (pdf)
  • Press: NASA Image of the Day, National Geographic, New York Times.

    Support: EPA, EPRI, NASA, NSF

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    Climate impacts on air quality

    Background:
    Weather is a major factor affecting surface air quality, and it follows that climate change could impose a significant "climate penalty" on pollution control strategies. In our ongoing Global Change and Air Pollution (GCAP) project, we investigate the impact of climate variables on air quality in the present-day and near future.

    Key questions:
  • What are the dominant meteorological drivers of U.S. surface ozone and particulate matter?
  • Should policymakers take into account a "climate penalty" on U.S. air quality?
  • Will future climate change exacerbate air quality in China?
  • What governs dust events in the western United States and how will climate change affect these episodes?

    People: Achakulwisut, Moch, Shen.

    Selected references:
  • Mickley, L.J., A.M. Fiore, and D.K. Henze, Interactions between climate change and U.S. air quality, EM, February, 30-34, 2014. EM is a journal for environmental managers. (pdf)
  • Shen, L., L. J. Mickley and A. P. K. Tai, Influence of synoptic patterns on surface ozone variability over the eastern United States from 1980 to 2012, Atmos. Chem. Phys., 15, 10925-10938, 2015. (pdf, sup)
  • Shen, L., L. J. Mickley and E. Gilleland, Impact of increasing heatwaves on U.S. ozone episodes in the 2050s: Results from a multi-model analysis using extreme value theory, Geophys. Res. Let., 43, 4017-4025, 2016. (pdf, sup)
  • Shen, L., and L.J. Mickley, Influence of large-scale climate patterns on summertime U.S. ozone: A seasonal predictive model for air quality management, PNAS, 114, 2491-2496, 2017. (pdf, sup)
  • Shen L., L.J. Mickley, and L.T. Murray, Influence of 2000-2050 climate change on particulate matter in the United States: Results from a new statistical model. Atmos. Chem. Phys., 17, 4355-4367, 2017. (pdf, sup)
  • Tai, A.P.K., L.J. Mickley, C.L. Heald, S. Wu, Effect of CO2 inhibition on biogenic isoprene emission: Implications for air quality under 2000-to-2050 changes in climate, vegetation, and land use, Geophys. Res. Let., 40, 3479-3483, 2013. (pdf, sup)
  • Wu, S., L.J. Mickley, J.O. Kaplan, and D.J. Jacob, Impacts of changes in land use and land cover on atmospheric chemistry and air quality over the 21st century, Atmos. Chem. Phys., 12, 15469-15495, 2012. (pdf)

    Press: Capital Public Radio, NBC, The Nation.

    Support: EPA, NASA, NIH

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  • Influence of climate on atmospheric oxidative capacity

    Background: The oxidative capacity of the troposphere determines the lifetime of many trace gases of imporance to climate and human health, including air pollutants and the greenhouse gas methane. In our project, ICE age Climate And Proxies (ICECAP), we investigate the drivers of changes in the oxidative capacity over long timescales and the implications of these changes for climate feedbacks.

    Key questions:
  • What controls oxidant levels on long timescales?
  • How have biogenic emissions changed over long timescales, and what are the implications of these changes for methane and the oxidative capacity?
  • People: Achakulwisut, Alexander, Kaplan.

    References:
  • Achakulwisut, P., L. J. Mickley, L. T. Murray, A. P. K. Tai, J. O. Kaplan, and B. Alexander, Uncertainties in isoprene photochemistry and emissions: Implications for the oxidative capacity of past and present atmospheres and for trends in climate forcing agents, Atmos. Chem. Phys., 15, 7977-7998, 2015. (pdf)
  • Alexander, B., and L. J. Mickley, Paleo-perspectives on potential future changes in the oxidative capacity of the atmosphere due to climate change and anthropogenic emissions, Current Pollution Reports, 1,, 57-69, 2015. (pdf)
  • Geng, L., L.T. Murray, L.J. Mickley, P. Lin, Q. Fu, A.J. Shauer, B. Alexander, Isotopic evidence of multiple controls on atmospheric oxidants over climate transitions, Nature, 2017. (pdf, sup)
  • Geng, L., M.C. Zatko, B. Alexander, T.J. Fudge, A.J. Schauer, L.T. Murray, and L.J. Mickley, Effects of postdepositional processing on nitrogen isotopes of nitrate in the Greenland Ice Sheet Project 2 ice core, Geophys. Res. Lett., 42, 5346-5354, 2015. (pdf, sup)
  • Murray, L.T., L.J. Mickley, J.O. Kaplan, E.D. Sofen, M. Pfeiffer, and B. Alexander, Factors controlling variability in the oxidative capacity of the troposphere since the Last Glacial Maximum, Atmos. Chem. Phys., 14, 3589-3622, 2014. (pdf, sup)
  • Sherwen, T., M.J. Evans, L.J. Carpenter, J.A. Schmidt, and L.J. Mickley, Halogen chemistry reduces tropospheric O3 radiative forcing, Atmos. Chem. Phys., 17, 1557-1569, 2017. (pdf)
  • Press: Xinhua, Science Daily.

    Support: NSF, NASA

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    Wildfires and agricultural fires: Links with atmospheric chemistry.

    Background:
    Wildfires and agricultural fires can have large impacts on air quality and atmospheric composition. For example, fires in Indonesia, used routinely to clear land for crops, can severely degrade air quality in megacities downwind. Through their effects on fires, both climate change and land-use decisions can have unexpected consequences for air quality. See also the following section, Consequences of changing air quality for human health.

    Key questions:
  • Will warmer temperatures or drier conditions increase wildfire frequency in the future? If so, what are the consequences for regional air quality?
  • What are the health consequences of agricultural fires in Equatorial Asia?
  • Do agricultural fires in India influence urban air quality downwind?

    People: Buonocore, Cusworth, DeFries, Jacob, Koplitz , Marlier, Myers, Schwartz.

    References:
  • Kim, P.S., D.J. Jacob, L.J. Mickley, S.N. Koplitz, M.E. Marlier, R. DeFries, S.S. Myers, and B.N. Chew, Sensitivity of population smoke exposure to fire locations in Equatorial Asia, Atmos. Environ., 102, 11-17, 2015. (pdf)
  • Koplitz, S. N., L. J. Mickley, M. E. Marlier, J. J. Buonocore, P. S. Kim, T. Liu, M. P. Sulprizio, R. S. DeFries, D. J. Jacob, J. Schwartz, and S. S. Myers, Public health impacts of the severe haze in Equatorial Asia in September-October 2015: A new tool for fire management to reduce downwind smoke exposure in the future, submitted to Environ. Res. Lett. , 2016. (pdf, sup)
  • Marlier, M., R. Defries, P.S. Kim, S.N. Koplitz, D.J. Jacob, L.J. Mickley, B.A. Margono, and S.S. Myers, Fire emissions and regional air quality impacts from fires in oil palm, timber, and logging concessions in Indonesia, Env. Res. Let., 10, 085005, 2015. (pdf, sup)
  • Marlier, M., R. Defries, P.S. Kim, D.L.A. Gaveau, S.N. Koplitz, D.J. Jacob, L.J. Mickley, B.A. Margono, S.S. Myers, Regional air quality impacts of future fire emissions in Sumatra and Kalimantan, Environ. Res. Letters, 10, 054010, 2015. (pdf, sup)
  • Marlier, M., R. Defries, D. Pennington, E. Nelson, E.M. Ordway, J. Lewis, S.N. Koplitz, and L.J. Mickley, Future fire emissions associated with projected land use change in Sumatra, Global Change Biology, 21, 345-362, 2015. (pdf, sup)
  • Yue, X., L.J. Mickley, J.A. Logan, R.C. Hudman, M. Val Martin, and R.M. Yantosca, Impact of 2050 climate change on North American wildfire: Consequences for ozone air quality, Atmos. Chem. Phys., 15, 10033-10055, 2015. (pdf, sup)
  • Yue, X., L.J. Mickley, and J.A. Logan, Projection of wildfire activity in southern California in the mid-21st century, Clim. Dyn., 43, 1973-1991, 2014. (pdf, sup)
  • Yue, X., L.J. Mickley, J.A. Logan, and J.O. Kaplan, Ensemble projections of wildfire activity and carbonaceous aerosol concentrations over the western United States in the mid-21st century, Atmos. Env., 77, 767-780, 2013. (pdf, sup)
  • Press: BBC, National Geographic, New Scientist, New York Times, The Guardian (twice), Wall Street Journal.

    Support: EPA, NASA, Rockefeller Foundation

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    Consequences of changing air quality for human health

    Background:
    Given recent and sometimes dramatic trends in emissions, climate change, and fire frequency, the atmosphere is in flux. We collaborate with biostatisticians and epidemiologists to probe the health consequences of changing air quality in the United States and elsewhere. See also the section on Wildfires and agricultural fires above.

    Key questions:
  • How will the frequency of "smoke waves" change in the western United States in a warming climate, and what are the consequences for acute health issues?
  • Will the combination of increasing heatwaves and changing pollution in future decades adversely affect human health?
  • How does pollution from fossil fuel combustion affect human health worldwide?
  • People: Bell, Dominici, Koutrakis , Liu, Schwartz, Shen, Sulprizio.

    References:
  • Lee, W.-C., L. Shen, P.J. Catalano, L.J. Mickley, P. Koutrakis, Effects of future temperature change on PM2.5 infiltration in the Greater Boston area, Atmos. Env., 150, 98-105, 2017. (pdf)
  • Liu, J.C., A. Wilson, L.J. Mickley, K. Ebisu, M.P. Sulprizio, Y. Wang, R.D. Peng, X. Yue, F. Dominici, and M.L. Bell, Who among the elderly is most vulnerable to exposure and health risks of PM2.5 from wildfire smoke? American Journal of Epidemiology, in press.
  • Liu, J.C., A. Wilson, L.J. Mickley, F. Dominici, K. Ebisu, Y. Wang, M.P. Sulprizio, R.D. Peng, X. Yue, J.Y. Son, G.B. Anderson, and M.L. Bell, Wildfire-specific fine particulate matter and risk of hospital admissions in urban and rural counties, Epidemiology, 28, 77-85, 2017. (pdf, sup)
  • Liu, J.C., L.J. Mickley, M.P. Sulprizio, X. Yue, R.D. Peng, F. Dominici, and M.L. Bell, Future respiratory hospital admissions from wildfire smoke under climate change in the western US, Env. Res. Let., 11, 124018, 2016. (pdf, sup)
  • Liu, J.C., L.J. Mickley, M.P. Sulprizio, F. Dominici, X. Yue, K Ebisul, G.B. Anderson, R.F.A. Khan, M.A. Bravo, and M.L. Bell, Particulate air pollution from wildfires in the Western US under climate change, Climatic Change, 138, 655-666, 2016. (pdf, sup)
  • Press: Climate Central, NASA Image of the Day.

    Support: NASA, NIH, Rockefeller Foundation, Wallace Global Fund.

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    Recent trends in key atmospheric species

    Background: As the observational record in the modern era lengthens, we can learn more about the mechanisms and sources of key atmospheric species and their changes over time. We can diagnose the impacts of policy measures, including unintended consequences, and detect shifts in pollution sources.

    People: Marais, Zhu.

    References:
  • Hickman, J.E., S. Wu, L.J. Mickley, and M.T. Lerdau, Kudzu (Pueraria montana) invasion doubles emissions of nitric oxide and increases ozone pollution, Proc. Nat. Acad. Sci., 107, (22) 10115-1-119, 2010. (pdf)
  • Marais, E. A., D. J. Jacob, J. R. Turner, and L. J. Mickley, Evidence of long-term decrease of biogenic secondary organic aerosol in response to SO2 emission controls, Environ. Res. Lett., 2017. (pdf)
  • Zhu, L., L. J. Mickley, D. J. Jacob, E. A. Marais, J. Sheng, L. Hu, G. Gonzalez Abad, and K. Chance, Long-term (2005-2014) trends in formaldehyde (HCHO) columns across North America as seen by the OMI satellite instrument: Evidence of changing emissions of volatile organic compounds, Geophys. Res. Lett., in review. (pdf)

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