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

• McDonald, Robert
• Marcotullio, Peter

Abstract
For the first time in history, a majority of people live in cities, and 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 2-5 and are increasingly vulnerable to environmental change6, 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 and may be key future vulnerabilities for urban residents. We propose to assemble an intellectually diverse Working Group to produce the first calculation of the global impact of urban activities on two ecosystem services: freshwater use and availability for drinking and sanitation; and 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 synthesize datasets of urban demographic, socio-economic, and biophysical change affecting the supply and demand of these two key ecosystem services. Our calculation of freshwater and atmospheric impacts will be incorporated into a high-profile scientific publication quantifying the ecological impact of future urbanization.