The Environmental, Social, and Health Dimensions of Urban Expansion

Abstract

In the coming decades, the world's rapid urbanization will be one of the greatest challenges to ensuring human welfare and a viable global environment. According to current estimates, cities occupy 4% or less of the world's terrestrial surface, yet they are home to almost half the global population, consume close to three-quarters of the world's natural resources, and generate three-quarters of its pollution and wastes. Moreover, the UN estimates that virtually all net global population and economic growth over the next 30 years will occur in cities, leading to a doubling of current populations. This growth will require unprecedented investment in new infrastructure and create undreamed of challenges for political and social institutions.Nowhere are the opportunities more promising or challenges to sustainability more daunting than in the rapidly urbanizing regions of the world. These transforming regions represent the engines of economic growth for the developing world and, everywhere will continue to be the centers of innovation, culture, and the arts. These same cities, however, are the loci of increasing poverty, pollution, disease, political instability, and social inequality. The transformation of surrounding land due to urban expansion and urban dwellers ever-increasing demand for energy, food, goods, and other resources is behind the degradation of local and regional environments, threatening basic ecosystem services and global biodiversity.

Used planet: A global history

“…Concentrating human populations within cities transforms the economies of scale in human interactions, producing higher average incomes and enabling a wide array of novel social benefits as urban systems advance (98,99), which in turn enable further growth and help to drive rural-urban migration (100,101). The massive food and resource demands of large, wealthy, and growing urban populations require high levels of agricultural surplus production and trade, which tend to be met by increasingly intensive and productive agricultural systems concentrated in Earth's most productive agricultural lands, supported by ever larger scales of farming operations, trading systems, and technological institutions (44,102).…”

Urban Governance of Biodiversity and Ecosystem Services

“…The environmental agenda of cities is thus necessarily woven into the history of the wider global environmental agenda (Sánchez-Rodríguez et al 2005 ;Seto et al 2012 ) and the development agenda (Parnell et al 2007 ). Recognizing cities as engines of economic growth and centers of production and consumption also implies acknowledging that cities draw on resources from all over the globe (Redman and Jones 2005 ). Signifi cantly, echoing a point made elsewhere in this volume, the new awareness of the importance of urban ecological governance reform bridged the global and local scales, and conceptualized cities as embedded in a larger natural hinterland -(a hinterland which, given new transportation and distribution capacities, may or may not be physically contiguous).…”

Urbanization and Inequality/Poverty

“…That second point (i) illustrates that cities in developing countries exercise an important migratory pull; and (ii) helps explain that urban areas will be the locus of all UN projected future population growth (over the next 40 years). Indeed, rural-urban migration accounts for around half of the total urban population in Africa [9].…”