Impacts of Megacities on Air Pollution and Climate (Invited Presentation)

Megacities are areas with the most intensive human activities, including economic and social activities, accompanied with tremendous energy consumption. These activities lead to concentrated emissions of air pollutants, greenhouse gases, and waste heat, which impact terrestrial and aquatic ecosystems as well as air quality and climate. The negative impact of megacities on local air quality has long been recognized. In recent years, the impact of anthropogenic emissions from megacities on regional and global climate has also received increasing attention. Both of these impacts are linked through energy consumption derived from fossil fuel combustion with emissions that change the atmospheric concentrations of short-lived species that impact both human health and climate, such as aerosols and ozone. Because of these linkages, it has been argued that megacities are the best places to realize the co-benefits of simultaneously controlling air pollution and reducing climate change.

With the growing trend towards urbanization, understanding the role of megacities in local to global atmospheric chemistry is critical to effectively realize the co-benefits of controlling air pollution and reducing climate change. The scientific and engineering knowledge that has been accumulated when developed megacities dealt with their air quality problems in earlier years is a significant resource for current and future megacities. Experiences of developed countries show that the pronounced air quality degradation that accompanied past development can be avoided. In recent years, there have been a growing number of internationally coordinated integrated studies and collaborative projects examining the impacts of megacities on air pollution and climate change. An assessment of these research results and general information about megacities.