The syllabus says
The global megacity
- Explain the global increase in the number and location of megacities (population over 10 million).
what is a megacity?
Definition: Megacities have 10 million in inhabitants or more.
Megacities are often agglomerations, created when two or more towns and cities grow so large that they join together. This is slightly different from a conurbation which occurs when two cities become treated as a single urban area, but there may still be green space between them. At the start of the 20th century, only London and New York could be considered megacities. At that time, just 2% of the world's population lived in cities. The following years saw an increase in the number and a change in distribution, to now when over 50% of people live in cities producing 80% of the world's economic output. Megacities are now growing fastest in the developing world. Due to their increasing size and the sheer number of people in them, megacities have specific problems such as water supply, waste management and the sustainability of the housing stock. A good video source discussing these issues is from CNBC here. |
Hong Kong is NOT a megacity because it doesn't have 10m people. However, it does have many features of a megacity such as high population density, clear economic functions such as financial centres and commercial centres, and it is the world's second largest port.
Source: Author's own picture |
where are the megacities?
In January 2015, China's Pearl River Delta conurbation overtook Tokyo as the world's largest city. However, this depends on how the 'city' is measured - the Pearl River Delta includes the cities of Shenzhen, Guangzhou, Foshan and Dongguan (but not Hong Kong, which is considered a separate territory under its 'Special Administrative Zone' status within China).
Most of the world's megacities are found in Asia. The reasons for this are explored below. Interactive sources The following two sites may be useful in describing the distribution and growth of megacities further: 1. The Smithsonian museum in the US has an excellent interactive site. 2. The UK Guardian newspaper website has a similar interactive site. |
Source: http://www.theguardian.com/global-development/interactive/2012/oct/04/rise-of-megacities-interactive
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The future of megacities
Megacities are predicted to continue to grow. This growth is very hard to predict because measurements are taken from so many different sources, and some may include fertility, while some may include migration, and some may make assumptions about the future mirroring the past. However, the graphic below shows a summary of some of the cities that are likely to become 10m strong by 2030.
Megacities are predicted to continue to grow. This growth is very hard to predict because measurements are taken from so many different sources, and some may include fertility, while some may include migration, and some may make assumptions about the future mirroring the past. However, the graphic below shows a summary of some of the cities that are likely to become 10m strong by 2030.
Source: http://www.bloomberg.com/infographics/2014-09-09/global-megacities-by-2030.html
Explaining the growth in megacities
Megacities - and all urban areas - grow in population due to two mechanisms:
1. Natural change See this page for further details about natural change in cities. 2. Migration Migration is responsible for much of the growth of cities in low and middle income countries. Rural dwellers tend to have more children than urban dwellers, so cities actually have a relatively low level of growth due to anything other than migration. A third cause of growth is the redrawing of city boundaries, or 'boundary redefinition'. As cities grow, the land around can be drawn into the city, resulting in the people who live there also being considered part of that city. The future of megacities
The graphic to the right shows the link between urban growth and GDP growth. In almost all cases, as GDP grows, the urban area becomes more attractive as they experience faster change. This is because cities are more efficient than rural areas - they have shorter distances to cover, and greater economies of scale. Limits to growth There are, however, potential limits to the growth of megacities. For example, in China, migration is regulated under the hukou system. This system permits people to live in a place, and receive social benefits such as healthcare or housing. Without permission to migrate to a city, people are likely to live in very poor conditions. Further limits include the future decline in birth rates, which is already being experienced in most low and middle income countries. |
Source: http://www.cnbc.com/id/101469042#.
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