Special issue on cities

in Sciencemagazine. Unfortunately the articles need subscription, but one can read the abstracts by clicking on some of the the articles. For example, clicking on Urbanization and the Wealth of Nations gives:
"Urbanization and the Wealth of Nations
David E. Bloom,* David Canning, Günther Fink
The proportion of a country's population living in urban areas is highly correlated with its level of income. Urban areas offer economies of scale and richer market structures, and there is strong evidence that workers in urban areas are individually more productive, and earn more, than rural workers. However, rapid urbanization is also associated with crowding, environmental degradation, and other impediments to productivity. Overall, we find no evidence that the level of urbanization affects the rate of economic growth. Our findings weaken the rationale for either encouraging or discouraging urbanization as part of a strategy for economic growth. "
and Urbanization and the Wealth of NationsGlobal Change and the Ecology of Cities gives:

"Global Change and the Ecology of Cities
Nancy B. Grimm,1* Stanley H. Faeth,1 Nancy E. Golubiewski,2 Charles L. Redman,3 Jianguo Wu,1,3 Xuemei Bai,4 John M. Briggs1
Urban areas are hot spots that drive environmental change at multiple scales. Material demands of production and human consumption alter land use and cover, biodiversity, and hydrosystems locally to regionally, and urban waste discharge affects local to global biogeochemical cycles and climate. For urbanites, however, global environmental changes are swamped by dramatic changes in the local environment. Urban ecology integrates natural and social sciences to study these radically altered local environments and their regional and global effects. Cities themselves present both the problems and solutions to sustainability challenges of an increasingly urbanized world. "