1. Discussion Space Research Centre

2. Urbanization and Industrialization: in 2008, more than half of humans live in cities UN Population Report 2007

3. CityZen Goals (in observational context) Quantify and understand current air pollution distribution and development in and around selected megacities/hot spot regions, including the interaction across the different spatial scales Estimate the future impact from emission changes with a focus on the effect of rapid growth in the population of megacities/hot spots and the increasing background of pollutants (concentrate on ozone O3, particulate matter PM, and their precursors) Estimate how megacities/hot spots influence climate change Estimate how megacities are responding to climate forcing which can influence transport patterns, chemical oxidation and biogenic emissions (especially biogenic volatile organic compounds BVOC)

4. CityZen Hypotheses 1.Megacities and hot spots have changed the regional and global distribution of ozone, particulate matter, and their precursors including carbon monoxide CO and other pollutants significantly compared to what would be the case with more evenly distributed emissions. 2.Megacities affect the radiative budget and aerosol microphysics 3.Climate change will change weather patterns (winds, temperature, stability, precipitation) and surface properties, which affect air quality in megacities and regional hot spots. If more frequent high pressure situations occur, episodes with reduced air quality will become more frequent. 4.Climate change will induce episodic and permanent changes in the natural and anthropogenic cycles of atmospheric trace chemicals. 5.Changes in frequency and intensity of forest fires and other biomass burning will at times contribute significantly to air pollution in megacities and hot spots. 6.Measures can be defined that reduce the adverse effects of megacity/hot spot emissions. The adverse effects relate both to air quality (human health) and climate change/weather modification. 7.The effect on air quality in some megacities following the replacement of gasoline in parts by biofuel is to reduce the formation of secondary pollutants: aerosols and ozone.

5. Observational Challenges Quantify the present levels and long-term changes of concentrations of pollutants (trace gases and aerosols) in hotspots and at rural sites and the contribution of pollutants from hotspots to transport and transformation of pollutants Quantify the impact of hotspots on air quality and pollution on regional and global scales Quantify the global contribution (including fires and biomass burning) to hotspots

6. Observations where do we stand? Detection of megacity signals Do we have a coherent observing strategy to fulfil our goals? Macro-scale - satellites Micro-scale – ground-based

7. Some Drivers Trends – accuracy, precision Composition – chemical markers Regional impact – spatial scales Policy metrics – two-way (observe measures, predict future)

8. So what have we found? It is important that we synthesise what we have found as we go along.

9. Work Package 3 CityZEN

10. Work Package 3 Megacity in the Future – Mitigation options for a sustainable Atmosphere Establish future scenarios of population development and needs for energy and how these reflect on emissions of the four hotspot cases (E Mediterranean, Po Valley, BeNeLux, Pearl River Delta) and the associated national, regional and global total emissions. Establish future scenarios of population development and needs for energy and how these reflect on emissions of the four hotspot cases (E Mediterranean, Po Valley, BeNeLux, Pearl River Delta) and the associated national, regional and global total emissions. On the basis of the emissions scenarios developed in this task and the nested model systems evolving from WP1 and WP2 calculate the changes in air quality in the four hotspot cases and the associated changes in pollutant fluxes between the hotspots and the surrounding regions for future time intervals (preliminary planned for 2030 and the 2050s). On the basis of the emissions scenarios developed in this task and the nested model systems evolving from WP1 and WP2 calculate the changes in air quality in the four hotspot cases and the associated changes in pollutant fluxes between the hotspots and the surrounding regions for future time intervals (preliminary planned for 2030 and the 2050s). On the basis of emission scenarios calculate the coupled climate change - hotspot air quality impact for the 2050s for the four hotspots. On the basis of emission scenarios calculate the coupled climate change - hotspot air quality impact for the 2050s for the four hotspots. Identify options to mitigate future environmental impacts on air quality and climate from the four hotspots. Make suggestions for a sustainable development. Identify options to mitigate future environmental impacts on air quality and climate from the four hotspots. Make suggestions for a sustainable development.

11. Tropical Challenge

12. The future... Royal Society Ozone Report, 2008

13. The push of technology... Royal Society Ozone Report, 2008

14. Research Tasks 1.Comparison and evaluation of existing emission inventories 2.Evaluate emissions from megacities with focus on hydrocarbons 3.Future emission scenarios 4.The impact of future emissions on air quality and climate 5.Quantify impacts of climate change on hotspot air quality and regional air pollution