Distinguishing between the Effects of Climate Change and Emission Mitigation on Ozone Concentration: Implications for Human Health Open Access

Stowell, Jen (2015)

Permanent URL: https://etd.library.emory.edu/concern/etds/5712m7555?locale=en


Given the potential threat to human health, it is vital to gain better understanding of hazards associated with climate, emissions, and air quality. Combinations of representative concentration pathways (RCPs) and downscaling models provide finer-resolution estimates of ozone (O3) effects on health at meaningful, local scales. Methods.An empirical model using statistical downscaling methods was developed for RCP4.5 (low emissions) and RCP8.5 (high emissions) to isolate O3 changes between 2001-2004 and 2055-2059 due to climate change. Parameters included temperature, relative humidity, planetary boundary layer, surface pressure, zonal/meridional wind speeds, precipitation, and stagnation. O3 changes attributable to both emissions and climate were isolated using dynamical downscaling for the same pathways.Future O3 concentrations from anthropogenic emissions were isolated using differences between the statistical and dynamical models. O3 changes were then converted to excess mortality values by county and region. Results.Climate change is expected to increase O3 in across the U.S. with a national average of 0.30 ppb (SE: 0.01) and 0.65 ppb (SE: 0.01) under RCP4.5 and 8.5, respectively. O3 contributions from a combination of climate and emissions could decrease by -2.6 ppb (SE: 0.02) under RCP 4.5 yet increase by 1.5 ppb (SE: 0.01) under RCP8.5. O3 due to emissions alone is expected to decrease by -3.2 ppb (SE: 0.01) under the RCP4.5 scenario. However, despite the emission reduction of O3 precursors planned under all pathways, O3 is expected to increase by 0.6 ppb (SE: 0.10) under RCP8.5. Discussion and Conclusions.This study demonstrates potential impacts of climate change, combined climate and emissions, and isolated emission changes on future O3 levels. Even with reductions in precursor emissions across all pathways, O3-related excess mortality may increase under RCP8.5. This indicates complications from methane emissions; expected to increase by 61% over 2005 levels by the 2050s under RCP8.5. This study has shown that substantial benefits may be achieved by mitigation of O3 precursors regardless of changing climate. However, to achieve maximum prevention, it is important to continue or intensify mitigation of greenhouse gases and O3 precursors (such as under RCP4.5) to avoid the cost to human health and quality of life. 

Table of Contents

Introduction    1

Data and Methods      7

Climate Dataset Descriptions7

Prediction of O3 change:        8

Statistical Downscaling and Future O3 from Climate Change Alone8

Dynamical Downscaling, Climate Change and Anthropogenic Emissions     10

Estimation O3 change from Anthropogenic Emissions Alone           11

Public Health Impact O3 from Anthropogenic Emissions      12


Prediction of O3 change:        14

Public Health Impact O3 from Anthropogenic Emissions      16

Discussion       17

References      21

Figures and Tables      27

Figure 1.  Climate regions of the continental U.S.      27

Figure 2.  Changes in meteorological parameters.    28

Figure 3.  Changes in Ozone Concentrations.30

Table 1.  Excess Mortality under RCP 4.5.      32

Table 2.  Excess Mortality under RCP 8.5.      35 

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