By 2030, the urban population will have risen to 5 billion or 60% of the global population.
50% of the urban population today is aged under 25.
Asia’s urban population is set to rise from 1.4 billion now to 2.6 billion in 2030 (equivalent to the world’s total population in 1955).
Africa’s urban population will rise from 300 to 750 million and that of Latin America and the Caribbean from 400 to 600 million.
Types of city
Urban areas with a population of over 10 million people are termed ‘ megacities ’.
There were around 20 of these in 2007; 75% are in the developing world and most continue to grow rapidly.
Strictly speaking, London is not a megacity, but if the population of the wider metropolitan area is taken into account, it comes very close to being one.
There are around 200 ‘ million cities ’ with populations of over 1 million.
‘ World cities ’ are those cities that wield huge economic and political power, such as New York, Tokyo (also megacities) and London.
Towns and cities grow in a number of ways:
Rural–urban migration is a key process.
Rural–urban migrants tend to be young and have high fertility; this boosts rates of natural increase in cities.
Rural–urban migration in the developing world is currently responsible for much urban growth.
Natural increase, especially in the developing world.
In the developed world, counter-urbanisation tends to balance the influx of migrants to towns and natural increase is low due to low fertility rates.
The more developed the megacity, the slower the rate of growth.
Megacities are very diverse.
Some are at the early or immature stage in the cycle of urbanisation, whereas in others the rate of growth is slowing ( consolidating ).
Developed world megacities ( mature ) tend to have very slow growth rates and are dominated by suburban sprawl. They are increasingly feeling the effects of counter-urbanisation.
Megacities (2) Jakarta Dhaka Karachi Lagos Mumbai Kolkata Cairo Delhi Manila Beijing Rio de Janeiro Shanghai Buenos Aires S ã o Paulo Mexico City Osaka-Kobe Tokyo Moscow Los Angeles New York Immature, rapidly growing South/southeast Asia and Africa Population under 30% urban 20%+ slums Consolidating, growing South America and southeast Asia Population 40–50% urban Under 20% slums Mature, slow growing Europe and North America Population 70%+ urban No slums
There will be a significant shifts in the distribution and ranking of megacities, with major cities in the poorer parts of Asia entering the top ten list.
New cities will also gain megacity status. By 2020 there could be close to 30 megacities, including: Istanbul, Guangzhou, Kinshasa, Lima, Tianjin, Lahore and Bogota.
Other rapidly growing cities likely to exceed the 10 million mark by 2020 are: Bangalore, Wuhan, Chennai (Madras), Tehran, Riyadh, Hyderabad, Baghdad and Hong Kong.
Top ten megacities, 2015 (predicted) 15.2 Dhaka 16.8 Jakarta 17 Calcutta 17.2 Shanghai 18.6 Delhi 19.9 New York 20.5 S ão Paulo 21 Mexico City 22.5 Mumbai 35 Tokyo 2015 population (millions)
60% of Mumbai’s population live in slums crammed on 6% of the city’s land.
Slums in Mumbai are growing at a rate of 2.2% per year.
The world slum population will rise from 1 billion in 2005 to an estimated 1.3–1.4 billion by 2020.
There are two views of slums and shanty towns:
One is that they are hotbeds of poverty and potential unrest.
The other is that, with a little effort and help, they can be improved to provide basic housing for the city’s poor.
Increasing numbers of people live in the slums and shanty towns of the developing world’s megacities:
Newcomers to developing world megacities face stark choices in terms of housing.
Some inhabit ‘old’ inner city slums (e.g. Dharavi in Mumbai).
They have the ‘advantage’ of being close to available work in the city.
Alternative squatter settlements spring up on the ‘septic urban fringe’.
Many of these slums and shanties are located on dangerously steep slopes, next to polluted rivers, on marshland or near polluting industry.
Megacity problems (1)
Sprawling slums Developing world
Explosive population growth
Poverty and prevalence of informal economy
Lack of clean water and sanitation
Urban funding crises
Lack of green space
Pollution of air and water
Gating and segregation
Visual and noise pollution
Water supply problems
Sprawling suburbs and exurbs Developed world
Megacity problems (2)
Finding solutions to these problems is becoming increasingly difficult.
In many developing cities, growth is clearly out of control with annual rates running at 6–8% per year in the worst cases.
Some possible solutions have been demonstrated: Curitiba in southeastern Brazil is a well-known example and Dongtan , China’s first ‘ ecocity ’ is attempting to create a sustainable urban area.
Megacity problems (3)
An important issue is planning. This is the key to Curitiba’s success, albeit this is only a small city of 1.8 million inhabitants.
If planners can control the growth and density of cities, they should be able to avoid the stifling congestion of high-density cities and the sprawling mass and high private transport use of low-density cities .
Urban resource use (1)
As urban areas grow they become voracious consumers of resources.
This results in deep eco-footprints and a huge amount of waste.
London’s urban metabolism is shown on the next slide:
London has a population of 7.5 million.
London recycles 18% of its waste.
Urban resource use (2)
London’s annual metabolism
60 million tonnes of carbon dioxide 4 million tonnes of household waste 11.4 million tonnes of industrial and demolition waste 400,000 tonnes of sulphur dioxide 280,000 tonnes of nitrogen oxides 7.5 million tonnes of wet, digested sewage sludge 20 million tonnes of fuel, in oil equivalent 40 million tonnes of oxygen 2.2 million tonnes of paper 2.4 million tonnes of food 1 billion tonnes of clean water 360 tonnes of glass 2.1 million tonnes of plastics 1.2 million tonnes of metals 1.2 million tonnes of timber 2 million tonnes of cement 36 million tonnes of bricks, blocks, sand and tarmac Outputs Inputs
Urban resource use (3)
To decrease the eco-footprints of urban areas and improve the quality of urban life ways need to be found to reduce both the inputs and outputs of cities. Some possible methods are outlined in the table below.
Using less polluting vehicles Using alternative (renewable) energy sources More recycling Reusing and recycling water More carbon sequestration (e.g. urban gardens, farms and forests) Water metering and mending leaking pipes Reducing packaging Introducing more public transport/more efficient vehicles Using recycled building materials Localising food distribution and improving storage Ways to reduce outputs Ways to reduce inputs