URBAN EXPANSION IMPACTS ON THE HEALTH OF ECOSYSTEMS, WILDLIFE AND HUMANS Panel Contribution to the PERN Cyberseminar on Urban Spatial Expansion by

On a global basis, it is estimated that the proportion of persons living in urban centers will increase to an unprecedented 65 % by the year 2030. The 2000 census shows that 80 % of the US population now lives in metropolitan areas, with 30 % in cities of 5 million or more. The environmental issues posed by such large population centers have profound impacts on public health beyond the city limits. The United Nations has estimated that by year 2015 there will be 26 “megacities ” (urban areas of 10 million inhabitants or more), most of them located in less industrialized nations. The factors causing the migration of masses of people from rural to urban areas are linked to environmental degradation. For example, desertification, deforestation, drought and salination of soils are common causes of human migration to cities in Asia and Africa. Deteriorating conditions are also linked to high human growth rates and the inability of local environmental systems to sustain them. However, the prevalence of pollution, together with inadequate sewer and sanitation infrastructure in urban areas, has led to environmental crises at a global scale. These changes in turn cause a cascade of factors that exacerbate disease emergence such as forest fragmentation, disease introduction, pollution and poverty. For example, recent research has shown that suburban sprawl, forest fragmentation and biodiversity loss are linked to Lyme disease risk in th