Environmental Engineering Reference
In-Depth Information
Energy
resources usage
Ozone layer
depletion
Climate change
Desertification
and drought
Water
resources
Land use
and forests
Biodiversity
loss
Population pressure
FIGURE 2.1
Relationships among desertification, climate change and biodiversity. (Adapted from The United
Nations Economic Commission for Africa (UNECA) and North Africa Office, The fight against
desertification and drought in North Africa,
The Eighteenth Meeting of the Intergovernmental
Committee of Experts
, United Nations Economic Commission for Africa, Tangiers, Morocco, 2008.)
and in the quest for fulfilling their needs in an urban context. Another
dimension related to population pressure in urban contexts is a city's grow-
ing size and its impact on climatic change. This is only one part of the
environmental chain of energy use, ozone depletion, desertification and bio-
diversity loss, as shown in Figure 2.1 [5].
2.2.1.1 Mega Growth, Mega Complexity
The megacity is a relatively new form of urban development. In 1950, there
were only two cities with populations of more than 10 million: New York
and Tokyo. By 1975, two more locations, Shanghai and Mexico City, joined
the club. However, by 2004, the number of megacities had rocketed to 22 and,
together, these cities now account for 9% of the world's urban population.
It is important to note that:
1. Mega cities' importance in the national and global economy is
disproportionately high.
2. City governance has to adapt to the challenge of delivering holistic
solutions across vast metropolitan regions.
3. City managers must strike the balance between three overriding
concerns: economic competitiveness, environment and quality of
life for urban residents.
Urban growth is spread unequally around the world, and the same is
true of its largest cities. Most of the megacities in the developed world are
growing slowly, if at all. Tokyo remains the largest with 35 million inhabit-
ants, but the fastest growth will be in the developing world (particularly in
Asia and Africa), placing huge pressure on infrastructure in those locations.
By 2020, Mumbai, Delhi, Mexico City, São Paulo, Dhaka, Jakarta and Lagos
