Mega Cities

Cities ...
Source: Kraas 2007

Mega cities are the urban phenomenon of this century and have particular significance in the world-wide process of urbanisation.

Megacities are defined as high-density metropolis with a population of over 5 million (Bronger 1996), more than 8 million (UN 1987), or more than 10 million inhabitants (Mertins 1992). Furthermore these agglomerations have a minimum level of population density (at least 2,000 person/km2). Other definitions only include cities with a single dominant centre (Bronger 1996, Kraas 2003).

Because of the fact that international statistics are not based on similar areas of reference, the figures given for the size of cities and megacities are generally not comparable but are used as the only available ones.

  • In 1950 the world had only four cities with population greater than 5 million
  • by 1985 already 28
  • in 2000 39 cities
  • In 2015 there will probably be almost 60 mega cities worldwide.

Two thirds of today's megacities are in developing countries, most of them in East and South Asia. Today megacities are home to less than 10% of the global urban population. In 2015 there will be about 604.4 million people (ca. 17%) living in megacities (Kraas 2003, UN-HABITAT 2001).

Megacities have a large number of specific problems with occasionally striking structural similarities. They often have more in common with each other than with their own hinterlands:

  • high population concentration and density
  • largely uncontrolled spatial expansion
  • high traffic levels, in some cases severe lacks of infrastructure
  • high concentrations of industrial production
  • signs of ecological strain and overload
  • unregulated and disparate land and property markets and insufficient housing provision
  • in some cases extreme socio-economic disparities
  • high level of dynamism in all processes (Kraas 2003)
U.S. urban definitions

But megacities are not only overcrowded places, some can be defined as global nodes and action spaces. Undisputedly megacities are economically active areas and nodal points of globalisation. Many megacities are pronounced primate cities with a high level of "functional primacy" (predominant position, overconcentration of the most important functions in the economic, cultural and political- administrative sectors). They are also often demographic primate cities, accommodating large parts of the countries' inhabitants. But, as a rule, megacities in developing countries ultimately do not play a significant political or economic role in the global urban system (Bronger 2004, Kraas 2003).

Mega Cities
Megacities with 5, 8 and 10 million inhabitants in the year 2000.
Source: Kraas 2003

Megacities are also global risk areas and especially proven to be highly vulnerable in crises and disasters. Threats can arise from environmental hazards like earthquakes and storms, floods, landslides, fires and droughts as well as from the global rise in sea-level. Man-made hazards threatening these huge cities are air, water and soil pollution, accidents, fires, industrial explosions, diseases and epidemics, socio-economic crises, civil riots and terror attacks. A particular problem also lies in the fact that existing administrations and their organizational structures are not designed for the scale to which these cities have meanwhile attained (Kraas 2003).

Meta cities

Metacities or hypercities are massive sprawling conurbations of more than 20 million people. Tokyo is the largest urban conglomeration in the world. By 2020, these cities will also have achieved metacity status: Mumbai, Delhi, Mexico City, Sao Paulo, New York, Dhaka, Jakarta and Lagos (UN-HABITAT 2001).

Tasks: 1. Construct a timeline to show the emergence and spreading of mega cities in the last 50 years and their future apprearance.
2. Explain the particular opportunities and contraints of mega cities in various regions of the world.