Urban world

Posted: 6 January 2008

In 2007, developing countries had some 2.4 billion urban dwellers compared with 900 million in industrialised countries. Half of all urban growth in developing countries was attributed to in-migration.

Over the next 30 years, virtually all population growth will be in the urban areas of developing countries. The urban population in the developing world will double to nearly 4 billion by 2030, according to UN projections. Over the same period, the urban population of developed countries is projected to increase from 900 million to 1 billion.

As populations grow, the number of large cities will increase substantially. By 2015 the world will have 520 cities with one million or more residents. Of these, some 400 - about three-quarters - will be in developing countries.


In 2005 there were 20 megacities with over 10 million inhabitants. By 2015, 22 cities will be this large, all but five of them in the developing world. By 2015, about 359 million people will live in these 22 megacities, 67 million more than today.

Cambodia. Credit: FAO

Pull and push factors

Urban areas attract people from smaller cities and the countryside in increasing numbers. They are pulled into cities because of the promise of employment opportunities, better education facilities, access to medical care and a host of other reasons. Mexico City, for instance, accounts for about 30 per cent of the country's total GDP, while greater Seoul has one-quarter of Korea's universities.

People are pushed out of rural areas and villages by lack of employment opportunities, environmental degradation and pressures on key resources - agricultural land, forests and water.

Housing crisis

According to UN estimates, about 1.3 billion urban residents currently live in inadequate housing. In many cities of the developing world, one-quarter to one-third of all residents lives in shanty towns, squatter settlements or slums. In these cities the housing sector needs to cope with an average additional demand for some 18 million housing units per year.

In 2003, the UN-Habitat report The Challenge of Slums: Global Report on Human Settlements, estimated that over 900 million people - one in every six human beings - are slum dwellers, and in 30 years' time that number is likely to double to 2 billion, unless serious action is taken.

The report's figures for the developing world are even starker: 43 per cent of the urban population of all developing countries combined live in slums, and over 78 per cent of the urban population in the Least Developed Countries live in slums.

Urban sprawl

As urban areas expand they over-run surrounding land. In developing countries, sprawl chews up one-half million hectares of land each year. In the US the urban corridor from Boston, Massachusetts to Washington DC is nearly a continuous chain of cities and towns that stretches 800 kilometres.

By far the largest and most crowded corridor is the vast urbanized region stretching 1,500 kilometers from Beijing to Seoul to Tokyo and containing over 100 million people in 112 cities of over 200,000 people each.

Ecological footprints

An ecological footprint is a measure of the impact or load that a given population has on nature. It represents the land area necessary to sustain current levels of resource consumption and waste disposal of a specific population. London's ecological footprint, for instance, has been estimated at 120 times the surface area of the city, or about 20 million hectares - nearly equivalent to the productive land area of Great Britain as a whole.

City residents of the industrialized world consume much more than those in developing countries, on average. At current consumption levels a typical North American city with a population of 650,000 requires about 30,000 square kilometres of land. A similar sized city in India requires only about 2,800 square kilometres of land.

Pollution and Health

Air pollution: Urban areas are responsible for approximately 80 per cent of global air pollution. Currently, over 1 billion urban residents are exposed to elevated levels of air pollution. An estimated 3 million people die every year, directly or indirectly, from the effects of air pollution. Nine in every 10 such deaths occur in the developing world.

The World Health Organization (WHO) estimates that about 700,000 deaths could be prevented every year in the cities of developing countries if just three major atmospheric pollutants - carbon monoxide, suspended particulate matter and lead - could be brought down to safe levels.

Water problems: Urbanisation dramatically increases per capita freshwater use. But many cities in the developing world are growing so fast that they cannot meet escalating demand. As a result, access to clean water actually diminished in most large urban areas in the developing world during the decade of the 1990s.

Many cities also lack adequate sanitation facilities. According to WHO, nearly two-thirds of urban populations in developing countries do not have adequate sanitation in that they lack access to a flush toilet, a sanitary latrine or even a pit that can be covered over.

Urban farming, Sanaa, Yemen. Credit: FAO

Urban agriculture

Worldwide some 800 million city dwellers are involved in urban and peri-urban agriculture on a small or large scale. Collectively, they produce about 15 per cent of the world's food.

Singapore provides one-quarter of its vegetables and much of its fish. Hong Kong produces two-thirds of its poultry and half its vegetables. In Cuba there are, according to the country's Ministry of Agriculture, some 150,000 acres of land being cultivated in urban and suburban settings. That represents thousands of community farms, ranging from modest courtyards to production sites that fill entire city blocks.