Chemistry-Climate Connections

We seek to understand factors controlling chemistry-climate interactions including the two-way couplings between air pollutants and climate.  Reducing emissions of some near-term climate forcing agents (NTCFs) such as methane, ozone, and some aerosols offers the potential to address jointly climate and air quality goals.  We also study the impacts of climate change on air pollution and the meteorology that drives regional pollutant responses. Our past work has  focused on quantifying climate and air pollution impacts resulting from changes in methane and ozone  (please see publications page).

Regional climate responses to aerosol vs. greenhouse gas forcings

tx90_for_webpageIn our research, we examine the role of aerosols aerosol versus greenhouse gas forcings on regional climate extremes (temperature and precipitation) over the United States.   We find that aerosols and greenhouse gases produce similar but opposite signed patterns of response in extreme temperatures [left], leading to large scale cancellations over the historical period [Mascioli et al. 2016].  Extreme precipitation over the eastern United States decreases in response to aerosols, particularly in winter, and increases over the eastern and central United States in response to greenhouse gases, particularly in spring. In the future, aerosol emissions are projected to decrease while greenhouse gas concentrations continue to rise.  As a result, the patterns of extreme temperature and precipitation associated with greenhouse gas forcing are expected to dominate over the twenty-first century. [Nora Mascioli]

Changing air pollution meteorology

Our recent work has examined changes in air pollution meteorology over the northeastern United States including changes in ventilating summertime storms [Turner et al., 2012] and in jet latitude [Barnes and Fiore, 2013] and the implications for surface ozone variability in this region. We are extending that work to other regions with a focus on extreme climate and pollution events [Nora Mascioli]

Lightning NOx in a changing climate

Reaction with the hydroxyl radical (OH) is the major loss pathway for many atmospheric pollutants, some reactive greenhouse gases and ozone depleting substances.  Earlier work, including some of our own (see publications page), indicates a strong sensitivity of tropospheric OH to lightning NOx, which is expected to change with climate.  We are investigating different model representations of lightning NOx and the implications for atmospheric oxidizing capacity.  [Lee Murray, supported by a NASA Postdoctoral Research Fellowship]

Cloud and precipitation response to regional aerosol perturbations

This work aims to systematically quantify the robust cloud and precipitation responses to regional changes in aerosols through model simulations using three fully coupled chemistry-climate models. We aim to better understand the magnitude, spatial and temporal pattern, statistical significance, and mechanisms responsible for remote and local climate response to a wide variety of regional aerosol perturbation simulations. Our results will inform the integrated assessment modeling community on the potential for and limitations of model emulation techniques for linking physical science with future climate impacts. Click here to read Westervelt et al. (2015) on this topic. [Dan Westervelt, Gus Correa, Arlene Fiore supported by NSF EaSM-3]

The impact of climate change on future air quality

The extent to which climate change can exacerbate or alleviate air pollution in the future is an important aspect of robust climate and air pollution policy decision-making. We use coupled chemistry-climate models, evaluated against a variety of surface and satellite observations, to determine the changes in particulate matter and ozone due to future climate changes. [Dan Westervelt, Arlene Fiore supported by EPA]
Current funding sources: EPA