Integrating Climate and Air Quality Decision-making

The problem:
The twin problems of climate change and “traditional” air pollution (mostly airborne particulate matter and surface-level ozone “smog”) are linked at several points. One ready example is particulates: reducing particulate exposures could substantially improve public health, but could also make an incremental contribution to global warming because particulates reduce insolation. Other examples include climate change mitigation strategies (e.g. carbon capture with amine scrubbers) with potentially significant air quality impacts or reductions in “black carbon” particles (soot) that lead to health benefits and may have significant, but highly uncertain, climate change co-benefits.

Analysts need a decision framework that is based on the multiple objectives that matter to decision makers and interested parties in order to incorporate these air quality and climate change implications into policy decisions. One key step is to broaden the set of objectives and performance metrics used to compare the consequences of alternatives. Past research has tended to focus on one problem or the other, and most atmospheric models are tailored to address only one side of the issue. A challenge is the need to consider widely disparate impacts, e.g. short-term, reasonably well quantified, public health impacts (i.e. mortality) resulting from air pollution versus a variety of longer term and more uncertain impacts resulting from climate change. Both problems lead to considerable ecosystem damages. For example, renewable energy such as solar and wind are inherently clean for air quality but their variability may require them to be paired with fossil fuel energy sources with very poor startup and shutdown pollutant emissions (193). Similarly, the effects of plug-in hybrid vehicles on air quality are complex, shifting emissions away from urban centers and depending greatly on when and how they are charged. On average, airborne particulate matter has had a cooling effect on climate that has partly offset greenhouse warming. This has led some to suggest that stringent air quality regulations on particulates are undesirable since these will accelerate warming in the short term. Such suggestions require critical and rigorous analysis since they imply ignoring serious public health problems related to air quality mortality.

The research:
Adams and colleagueswill build on climate and air quality modeling expertise at CMU to address the impacts of policies on both problems in a rigorous way. Our past research has built a common air quality and climate modeling framework that merges climate and meteorological models with air quality models to simulate climate and air pollution from global to urban scales. Specifically, we will address the following objectives:

  1. expand our climate and air quality modeling system to support decision-making by including a range of future policy choices (e.g. plug-in hybrids and renewables) and impact assessments (ecosystem, public health, and climate impacts);
  2. develop multi-attribute metrics and decision-making methodologies to support consideration of the various impacts and time horizons or policies;
  3. evaluate the air quality impacts of climate mitigation policies (plug-in hybrids, renewables, carbon capture) under a variety of deployment scenarios;
  4. evaluate the magnitude of potential “co-benefits” between controls on soot and methane;
  5. evaluate the air quality benefits of particulate matter reductions versus short-term warming impacts. These activities integrate atmospheric modeling expertise in CMU’s Center for Atmospheric Particle Studies, life-cycle assessment and climate metrics (CMU’s Green Design Institute), and work on soot in developing countries (UBC).

The decision makers:
EPRI, IRGC, NRDC, Peabody.  In addition, the investigators have long-standing collaborative ties with a number of state and regional air quality control groups.