Ecosystem services on an urbanizing planet: What 2 billion new urbanites means for air and water

For the first time in history, a majority of people live in cities. Urbanization is expected to add almost 2 billion new urban residents by 2030. While there is growing awareness that cities affect almost every ecosystem on Earth and are increasingly vulnerable to environmental change, there are few global estimates of urbanization's impact on key ecosystem services. This is particularly true for freshwater availability and clean air, which may be massively impacted by urbanization. Our Working Group will produce the first calculation of the global impact of urban activities on two ecosystem services. The first is freshwater use and availability for drinking and sanitation. The second is the atmosphere's capacity to absorb pollutants such as particulate matter, ozone, and carbon dioxide from fossil-fuel consumption, while remaining healthy to breathe and avoiding extreme climate change. During our meetings scientists and policymakers will use information on urban demography, economics, and ecology to model the supply and demand of these two key ecosystem services.