【11】The resilience of the built environment

An increase in the urban footprint brought about by population growth fundamentally alters the structure of a city and can have significant impacts on its identity, many of which would be seen as negative. Urban sprawl can reduce livability and environmental efficiency, and can have an irreversible impact on the natural environment (e.g. due to land clearing). 

Increased traffic congestion arising from population and economic growth can significantly affect the function of a city. Some of the ways in which this might be mitigated (e.g. building additional roads) impact on the structure and possibly the identity of the built environment. On the other hand, growth in traffic congestion can be mitigated through increased use of public transport, which has a much smaller impact on the structure.

Pollution may lead to an increase in episodes of poor air quality. The frequency, duration and severity of these episodes are influenced by short-term meteorological conditions and local topography, and air quality is usually restored to acceptable levels once the immediate conditions change. However, human resilience in the face of prolonged or recurring exposure to air pollutants is limited.

The resilience of the built environment in the face of increased consumption depends on the extent to which the built environment system itself leads to increases in efficiency. There are mixed views on whether urban systems create efficiencies in the use of environmental resources; many improvements in environmental efficiency tend to result from factors 'outside' the system, such as changed behaviors and technological improvements.