The total amount of land dedicated to urban uses increased from 21 million hectares in 1982 to 26 million hectares in 1992. Land pressures are even greater in developing countries with high rates of urban population growth. A round certain cities, urban land expansion is occurring even faster. In Sao Paulo, Brazil, the urban core grew from an area of 180 square kilometers in 1930 to more than 900 square kilometers in 1988. The example of Sao Paulo shows that it is not necessarily the scale of urban land conversion that is so important as the type of land being lost.
Urban development can push agriculture to less suitable land, with unintended results.
Squatter settlements are commonly found on steep hillsides vulnerable to landslides and soil erosion, on water catchment areas, on protected lands, and on land subject to flooding or tidal inundation. Although the poor are aware that their settlements lie in precarious locations, the lack of alternative land for housing leaves them no choice. Urban land use planning can help guide urban development away from vulnerable ecosystems. Such policies will not work, however, unless cities also provide adequate land for housing, for industries and commerce, and for public infrastructure and buildings. Accordingly, urban impacts along the coasts stand to increase markedly in the years ahead.