Abstract
Abstract. The atmospheric chemistry general circulation model EMAC has been used to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050). The emission scenario assumes that population and economic growth largely determine energy and food consumption and consequent pollution sources with the current technologies ("business as usual"). This scenario is chosen to show the effects of not implementing legislation to prevent additional climate change and growing air pollution, other than what is in place for the base year 2005, representing a pessimistic (but plausible) future. By comparing with recent observations, it is shown that the model reproduces the main features of regional air pollution distributions though with some imprecisions inherent to the coarse horizontal resolution (~100 km) and simplified bottom-up emission input. To identify possible future hot spots of poor air quality, a multi pollutant index (MPI), suited for global model output, has been applied. It appears that East and South Asia and the Middle East represent such hotspots due to very high pollutant concentrations, while a general increase of MPIs is observed in all populated regions in the Northern Hemisphere. In East Asia a range of pollutant gases and fine particulate matter (PM2.5) is projected to reach very high levels from 2005 onward, while in South Asia air pollution, including ozone, will grow rapidly towards the middle of the century. Around the Persian Gulf, where natural PM2.5 concentrations are already high (desert dust), ozone levels are expected to increase strongly. The population weighted MPI (PW-MPI), which combines demographic and pollutant concentration projections, shows that a rapidly increasing number of people worldwide will experience reduced air quality during the first half of the 21st century. Following this business as usual scenario, it is projected that air quality for the global average citizen in 2050 would be almost comparable to that for the average citizen in East Asia in the year 2005, which underscores the need to pursue emission reductions.
Highlights
Clean air is a prerequisite to human health and well-being
We present a Business as Usual (BaU) scenario to illustrate the effects on the atmospheric composition that can be avoided by implementing additional emission control measures
Though the EMAC model accounts for high time resolution variability (10 min time step) and applies monthly emissions, we largely focus on annual averages in the analysis of the results
Summary
Clean air is a prerequisite to human health and well-being. In spite of the introduction of less polluting technologies in industry, energy production and transport during the past decades, air pollution remains a major health risk (HTAP, 2010). Hogrefe et al, 2004; Jacobson and Streets, 2009) They included a range of optimistic and pessimistic scenarios for gases influencing climate change, but did not consider further air pollution emissions controls, except for SO2. The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP, www.giss.nasa.gov/projects/accmip/) was initiated, which focuses on emission scenarios based on the Representative Concentration Pathways (RCP) (Lamarque et al, 2011; Meinshausen et al, 2011; van Vuuren et al, 2011a,b, and references therein) These scenarios, implicitly assume air pollution controls and are lacking a “worst case” scenario. We present a Business as Usual (BaU) scenario (which represents a possible future with continuation of the past emission trends and without additional legislation to abate increasing air pollution and climate change) to illustrate the effects on the atmospheric composition that can be avoided by implementing additional emission control measures.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
