Urban ecology: policy issues resolved and unresolved

Abstract

Our contemporary world is an urban world (Pacione, 2005). In 2008 the proportion of people living in urban areas equalled their rural counterparts and it is expected that 70 per cent of the world population will inhabit urban areas by 2050 (United Nations, 2008). Over the next 40 years a marked increase in the world urban population in developing countries in Africa and Asia is predicted, with a decrease in developed countries in Europe and North America (United Nations, 2008). Specifically, Venard (1995) predicted a growth in urban population of 473 per cent for Sub-Saharan Africa from 1990 to 2025, with an expected 11 cities exceeding 5 million inhabitants by 2025 in comparison with none in 1990. These exponential urban population growth rates will definitely have farreaching social, economic and environmental implications on the future of our world. Change in land cover patterns influencing climate, decrease and contamination of water sources, transformation and fragmentation of natural habitats, alteration of species composition leading to biotic homogenization, and a depletion of ecosystem services offered by natural ecosystems (McPherson, 1998; Whitford et al., 2001, Tratalos et al., 2007; Wu, 2008) are only some of the environmental consequences of increasing urbanization. Although these environmental impacts of urbanization are locally intense, cities also form 'ecological footprints' for different resources that may stretch far beyond the city limits (Wu, 2008)