Western society has become the model for the rest of the world, particularly in developing countries with rapidly growing populations.

While farming is linked to the land, the cities hold the promise of pleasure and the hope of being rich some day. But the wait for this promise to be fulfilled can be long and miserable.

We need to make changes on two levels: We must improve the situation of the poor in large cities. This presupposes the existence of municipal powers capable of making change and able to count on the support of their citizens. At the same time, we must limit the waste of wealthy cities that use natural resources as if they were inexhaustible and contribute to pollution.

Humans are reclaiming their "right to the city"; but this "right" must be placed in the context of global solidarity. We have chosen four cities to illustrate different ecological approaches: Kalundborg for its industrial ecology; Stockholm for its tradition of ecological awareness; Curitiba for its social ecology; and Pôrto Alegre for its political ecology.