The impact of emissions and climate change on future ozone concentrations in the USA
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The impact of emissions and climate change on future ozone concentrations in the USA Mojtaba Moghani1
· Cristina L. Archer1
Received: 29 April 2020 / Accepted: 3 August 2020 © Springer Nature B.V. 2020
Abstract The potential impacts of climate change and future anthropogenic emissions on ozone levels in the USA are examined by linking global climate models to regional meteorological and air quality models during 3-year summer periods over the nine climate regions of the continental United States for three cases: (1) using 2016 meteorology and emissions (CTRL), (2) using 2050 meteorology and 2016 emissions (CASE1), and (3) using 2050 meteorology and 2050 emissions (CASE2). As climate change alone is expected to worsen ozone pollution and emission reductions are expected to reduce ozone concentrations, in this paper, the non-linear response of future ozone levels to both meteorological conditions and emissions was studied. The results show the well-known positive ozone correlation with surface temperature and negative ozone correlation with humidity in all regions. Climate change alone will increase future MDA8 ozone in the USA by 3.6 ppb. With climate change and policy intervention based on RCP 8.5, ozone levels will decrease 7.2 ppb on average for all climate regions in the USA. Furthermore, while climate change alone will double the number of stations violating the current National Ambient Air Quality Standard (NAAQS) for ozone in 2050, when policies are in effect, this number was reduced to 21 stations. The number of high-ozone days will also increase in climate change only case in all regions with an average of 5.7 extra highozone days which confirms previous studies. The results show that even with high-ozone precursor reductions, the ozone levels will still violate the current national ozone standard. Therefore, in order to meet the current ozone standard by 2050, more stringent climate and air pollution control policies for most regions in the USA are needed. Keywords Air pollution · Ozone · Air quality modeling · Climate change · Emissions
Introduction Future projections of air quality should account for changes in both climate and emissions due to their combined impacts on air quality. For ground-level ozone pollution, the most important factors are precursor emissions (NOx and VOC) and favorable meteorological conditions (Jacob and Winner 2009; Nolte et al. 2008). Although the emissions of ozone precursors in the USA have declined significantly in the past decades and led to improvements in air quality and human health (United States Environmental Protection Agency 2012), climate change itself will worsen ozone pollution by
Mojtaba Moghani
[email protected] 1
Interdisciplinary Science and Engineering Laboratory (ISELab), University of Delaware, 221 Academy St, Newark, DE, 19716, USA
increasing the frequency of high-ozone days by mid-century (Archer et al. 2019) in the absence of emission changes. As ozone pollution is highly sensitive to meteorology, climate change has the potential to affect air
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