CITIES: CHALLENGES AND OPPORTUNITIES FOR SUSTAINABILITY BRANTLEY LIDDLE
AND FRED MOAVENZADEH OR at least 4000 years, cities have been centers of
cultural, social, technological Fand economic innovation, inventions and
their application, and political power. Only in the last 200 years, the
industrial era, have urban areas grown so rapidly, and their populations
increased so dramatically that their impacts on the natural environ-
ment are being felt beyond their immediate geographic surroundings. As
the 21" cen- tury dawns, megacities-great and far-reaching
concentrations of power and influ- ence-have become centers of the
phenomena of globalization and information ex- change. These
concentrations of people and activity are placing stress on the natural
environment so great that it is beginning to have extensive regional,
and even global impacts. However, asconcentrations ofpower-political,
economic, andintellectual- these great urban centers share with the
ancestral cities of past millennia the resources to consciously shape
the future. The management of these megacities (those having populations
of over eight million) in their current formative stages so taxing to
natural systems, paradoxicallypresents theopportunity
torestoresustainableregional and global environments. Environmental
problems consequent to urban growth have two sources: pov- erty and
affluence. These two conditions often coexist in dramatic contrast
within the same city, particularly in developing countries. In terms of
environmental impact, poverty-based problems tend to have local effects,
while affluence-based problems usually have transboundary and/or global
effects.