Projecting state-level air pollutant emissions using an integrated assessment model: GCAM-USA

Abstract

Integrated Assessment Models (IAMs) characterize the interactions among human and earth systems. IAMs typically have been applied to investigate future energy, land use, and emission pathways at global to continental scales. Recent directions in IAM development include enhanced technological detail, greater spatial and temporal resolution, and the inclusion of air pollutant emissions. These developments expand the potential applications of IAMs to include support for air quality management and for coordinated environmental, climate, and energy planning. Furthermore, these IAMs could help decision makers more fully understand tradeoffs and synergies among policy goals, identify important cross-sector interactions, and, via scenarios, consider uncertainties in factors such as population and economic growth, technology development, human behavior, and climate change. A version of the Global Change Assessment Model with U.S. state-level resolution (GCAM-USA) is presented that incorporates U.S.-specific emission factors, pollutant controls, and air quality and energy regulations. Resulting air pollutant emission outputs are compared to U.S. Environmental Protection Agency 2011 and projected inventories. A Quality Metric is used to quantify GCAM-USA performance for several pollutants at the sectoral and state levels. This information provides insights into the types of applications for which GCAM-USA is currently well suited and highlights where additional refinement may be warranted. While this analysis is specific to the U.S., the results indicate more generally the importance of enhanced spatial resolution and of considering national and sub-national regulatory constraints within IAMs.

Source Apportionments of Aerosols and Their Direct Radiative Forcing and Long‐Term Trends Over Continental United States

“…East Asia has a much larger contribution to aerosols in the free troposphere over the United States, where they have offset much of the warming forcing in western United States that would otherwise have been associated with reductions in U.S. domestic emissions. As U.S. domestic emissions continue to decrease due to current polices (Shi et al, ), the relative impact of foreign emissions may well continue to increase. It is, therefore, important for future projections to consider the potential impact of foreign emissions on radiative forcing, but also on surface concentrations, particularly in western United States.…”

State-level drivers of future fine particulate matter mortality in the United States

“…Second, population growth not only boosts energy demand but also typically increases population exposure to air pollution. Third, the challenges and opportunities for reducing adverse PM 2.5 health impacts may differ considerably among states, depending on historical energy use patterns (Brown et al 2018), and regional policies (Shi et al 2017), such as the cross-state air pollution rule (CSAPR) (EPA 2011a) which caps electric sector emissions of NO x and SO 2 for 23 states.…”

Air pollution control strategies directly limiting national health damages in the US

“…We define a reference scenario (BASE REF) that includes updated baseline assumptions about technology trajectories harmonized with the 2018 Energy Information Administration (EIA) Annual Energy Outlook (AEO) 23 , as well as an alternative reference scenario (HR REF) with much higher shares of wind and solar generation (e.g., 48% versus 25% in 2050), intended to reflect a continuation of recent, rapid growth in renewables. For both, major air pollutant and CO 2 emission regulations currently in place are represented 24 , assuming no additional future regulations ("Methods"). Electric sector coal use in HR REF decreases by 51% from 2015 to 2050, compared with the 8% increase in BASE REF ( Supplementary Fig.…”

“…2). Electricity generation is not a major sector for achieving PMMC reductions in these scenarios, because existing regulations incorporated in REF already reduce NO x , SO 2 , and primary PM 2.5 emissions from the electric power sector by 2050, particularly from coal-fired power plants 24,25 . US50 also has a negligible effect on the transportation sector, because emission standards for new on-road vehicles result in a much lower polluting fleet by 2050.…”

“…GCAM-USA estimates air pollutant emissions as the product of an economic activity (energy input or service output of a specific technology) and the corresponding emission coefficient. In our previous work 21,22,24 , we have attempted to harmonize emission coefficients with EPA's National Emission Inventory (NEI) and its projections, and have included representations of important existing national and regional air quality, climate, and energy policies. These state-level updates allow a more a realistic reference scenario that serves as the baseline for examining additional PM 2.5 mortality cost reductions.…”