ABSTRACT
The persisting dynamic urban change processes, especially the tremendous worldwide expansion of urban population and urbanized area, affect and drive natural and human systems at all geographic scales. Although urban areas occupy only about 3% of the Earth’s surface, their impact on surrounding rural areas is also rapidly increasing. Urbanization not only concentrates people (and therefore the demand for all social and economic services they require); it also creates hot spots for energy consumption, natural resource consumption, and emissions of pollutants and greenhouse gases, and acts as nodes linking communications and transport infrastructure — themselves all too often a source of pressure on the surrounding environment.
