Urbanization - both as a social phenomenon and a physical transformation of landscapes - is one of the most powerful, irreversible and visible anthropogenic forces on earth. Many of the most important and significant changes associated with the impact of globalization are taking place in urban areas. More than half of the world's population lives in urban areas and more than 90 percent of future population growth is likely to be concentrated in cities, mainly in poor countries. Rapid growth of population and its concentration in urban areas have significant implications for the long-term outlook for humanity.

Burdened with many problems associated with growth, urban areas are increasingly subject to dramatic crises. This is especially true in poor countries where economic and financial crises, together with fast and unbalanced growth of urban areas, have created fragmented spaces which aggravate social segregation. The aforementioned problems play an important role in the interactions between urban areas and global environmental change. These interactions create a diversity of impacts that can be grouped in two broad categories: those originating in urban areas that have a negative effect on global environmental change, and global environmental changes that have negative effects on urban areas.

Despite their growing importance, urban areas have been understudied in the analysis of global environmental change, with a majority of research placing emphasis on the impacts of urban areas on global environmental change. Research efforts focus particularly on the contributions of emissions of greenhouse gases and the heat island effect to global climate change. Much less attention has been devoted to the study of the impacts of global environmental change on urban areas and the people who live in them. Particularly critical are the conditions in poor countries.