Nicholas Z. Muller

Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security

Why Wait? Tropospheric ozone can be dangerous to human health, can be harmful to vegetation, and is a major contributor to climate warming. Black carbon also has significant negative effects on health and air quality and causes warming of the atmosphere. Shindell et al. (p. 183) present results of an analysis of emissions, atmospheric processes, and impacts for each of these pollutants. Seven measures were identified that, if rapidly implemented, would significantly reduce global warming over the next 50 years, with the potential to prevent millions of deaths worldwide from outdoor air pollution. Furthermore, some crop yields could be improved by decreasing agricultural damage. Most of the measures thus appear to have economic benefits well above the cost of their implementation. Reducing anthropogenic emissions of methane and black carbon would have multiple climate and health benefits. Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at

Global Air Quality and Health Co-benefits of Mitigating Near-Term Climate Change through Methane and Black Carbon Emission Controls

700 to

Linking Policy to Statistical Uncertainty in Air Pollution Damages

5000 per metric ton, which is well above typical marginal abatement costs (less than

Using air quality modeling to study source-receptor relationships between nitrogen oxides emissions and ozone exposures over the United States.

250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide–reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold.

Regulating NOx and SO2 Emissions in Atlanta

Background: Tropospheric ozone and black carbon (BC), a component of fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter; PM2.5), are associated with premature mortality and they disrupt global and regional climate. Objectives: We examined the air quality and health benefits of 14 specific emission control measures targeting BC and methane, an ozone precursor, that were selected because of their potential to reduce the rate of climate change over the next 20–40 years. Methods: We simulated the impacts of mitigation measures on outdoor concentrations of PM2.5 and ozone using two composition-climate models, and calculated associated changes in premature PM2.5- and ozone-related deaths using epidemiologically derived concentration–response functions. Results: We estimated that, for PM2.5 and ozone, respectively, fully implementing these measures could reduce global population-weighted average surface concentrations by 23–34% and 7–17% and avoid 0.6–4.4 and 0.04–0.52 million annual premature deaths globally in 2030. More than 80% of the health benefits are estimated to occur in Asia. We estimated that BC mitigation measures would achieve approximately 98% of the deaths that would be avoided if all BC and methane mitigation measures were implemented, due to reduced BC and associated reductions of nonmethane ozone precursor and organic carbon emissions as well as stronger mortality relationships for PM2.5 relative to ozone. Although subject to large uncertainty, these estimates and conclusions are not strongly dependent on assumptions for the concentration–response function. Conclusions: In addition to climate benefits, our findings indicate that the methane and BC emission control measures would have substantial co-benefits for air quality and public health worldwide, potentially reversing trends of increasing air pollution concentrations and mortality in Africa and South, West, and Central Asia. These projected benefits are independent of carbon dioxide mitigation measures. Benefits of BC measures are underestimated because we did not account for benefits from reduced indoor exposures and because outdoor exposure estimates were limited by model spatial resolution.

Damages and Expected Deaths Due to Excess NOx Emissions from 2009 to 2015 Volkswagen Diesel Vehicles

Abstract This study uses Monte Carlo analysis to characterize the uncertainty associated with per-ton damage estimates for 565 electric generating units (EGUs) in the contiguous United States (U.S.) This analysis focuses on damage estimates produced by an Integrated Assessment Model (IAM) for emissions of five local air pollutants: sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), ammonia (NH3), and fine particulate matter (PM2.5). For each power plant and pollutant, the Monte Carlo procedure yields an empirical distribution for the damage per ton, or marginal damage. The paper links uncertainty in marginal damages to air pollution policy in two ways. First, the paper characterizes uncertainty in the magnitude of the marginal damages which is relevant to policymakers in determining the stringency of pollution controls. Second, the paper explores uncertainty in the relative damages across power plants. Relative damages are important if policymakers elect to design efficient regulations that vary in stringency according to where emissions are released. The empirical section of the paper finds that the marginal damage distributions are positively skewed and they are more variable for sources in urban areas than rural locations. The paper finds that uncertainty in three input parameters has the greatest impact on uncertainty in the magnitude of damages: the adult mortality dose-response parameter, the mortality valuation parameter, and air quality modeling. The analysis also finds that for each pollutant except for NOx only uncertainty in air quality modeling impacts efficient trading ratios calibrated to each firms marginal damages.

Boosting GDP growth by accounting for the environment

Human exposure to ambient ozone (O(3)) has been linked to a variety of adverse health effects. The ozone level at a location is contributed by local production, regional transport, and background ozone. This study combines detailed emission inventory, air quality modeling, and census data to investigate the source-receptor relationships between nitrogen oxides (NO(x)) emissions and population exposure to ambient O(3) in 48 states over the continental United States. By removing NO(x) emissions from each state one at a time, we calculate the change in O(3) exposures by examining the difference between the base and the sensitivity simulations. Based on the 49 simulations, we construct state-level and census region-level source-receptor matrices describing the relationships among these states/regions. We find that, for 43 receptor states, cumulative NO(x) emissions from upwind states contribute more to O(3) exposures than the states own emissions. In-state emissions are responsible for less than 15% of O(3) exposures in 90% of U.S. states. A states NO(x) emissions can influence 2 to 40 downwind states by at least a 0.1 ppbv change in population-averaged O(3) exposure. The results suggest that the U.S. generally needs a regional strategy to effectively reduce O(3) exposures. But the current regional emission control program in the U.S. is a cap-and-trade program that assumes the marginal damage of every ton of NO(x) is equal. In this study, the average O(3) exposures caused by one ton of NO(x) emissions ranges from -2.0 to 2.3 ppm-people-hours depending on the state. The actual damage caused by one ton of NO(x) emissions varies considerably over space.

Using index numbers for deflation in environmental accounting

Abstract Through a series of experiments, we measure the marginal damage of emissions near Atlanta using a sophisticated integrated assessment model. The marginal damages of sulfur dioxide (SO2) are driven by proximity to downtown Atlanta; emissions produced closer to the city lead to higher exposures and therefore damages.The spatial pattern in damages from nitrogen oxide (NOx) emissions are more complex because of the powerful role of atmospheric chemistry. NOx emissions from ground-level sources in downtown Atlanta reduce aggregate exposures to both the tropospheric ozone as well as small particulates. In contrast, NOx discharges in suburban or rural areas lead to higher exposures and damages from both pollutants. These findings raise questions about the current policy of treating all NOx and SOx emissions as though they are alike.

Does environmental policy affect scaling laws between population and pollution? Evidence from American metropolitan areas

We estimate the damages and expected deaths in the United States due to excess emissions of NOx from 2009 to 2015 Volkswagen diesel vehicles. Using data on vehicle registrations and a model of pollution transport and valuation, we estimate excess damages of

The distribution of income is worse than you think: Including pollution impacts into measures of income inequality

430 million and 46 excess expected deaths. Accounting for uncertainty about emissions gives a range for damages from