The Challenges of an Urban World

Urbanisation the movement of people from rural areas to urban areas like towns and cities

Urbanisation is happening around the world, and in 2007, for the first time, the number of people living in urban areas was greater than the number of people living in rural areas. However, the number of people living in urban areas is not the same across the world and it varies between places. In the developed world, 78% of the population live in urban areas while in the developing world, only 46% of the population live in urban areas.

Urbanisation in developed countries

Urbanisation in developing countries

World Cities & Megacities

World cities:

Examples of world cities include London, Paris, New York, Beijing, New Delhi and Singapore


Examples of megacities include New York, Los Angeles, Mexico City, Osaka and Shanghai

Spatial Growth

The spatial growth of a megacity is usually different depending on whether it is developed or not.

Developed world:

Developing world:

Population of megacities

Problems facing developed world megacities

Problem Case Study - New York
Getting food for the 10 million plus inhabitants is a difficult task and food will often have to be imported from other countries. The transportation from far-fetched countries will inevitably add to the cost of the product to the consumer and also the carbon footprint of the city. People living in these megacities are being encouraged to buy more locally produced food The food supply of New York takes 6 million hectares of farmland. The large majority of it is transported by lorries.
A large megacity is going to use a lot of electricity and gas for the many homes and businesses and getting all the energy needed for the city is no easy task. The city will have to decide how it is going to generate this energy, especially with fossil fuels running out. They could use coal-fired power-stations, but these release a lot of unwanted pollution into our air. Nuclear power is also an option, but this is very dangerous with the potential of radiation being released. Regardless of how it generates it energy, huge amounts of of resources will be used. Each year, New York uses 50,000 gigawatts of electricity, mostly produced by oil, gas and nuclear-fuelled power stations.
Any large city will face problems with congestion on roads as the large volumes of people all try to get around the city. All the cars will also be polluting the air so the air quality in a megacity will not be very good despite technology helping more modern cars producing less pollution. The rest of the city's transport infrastructure (rail, tube, buses, etc.) will also be under a lot of stress. Like lots of other cities, New York suffers from congested roads and poor air quality.
Another major challenge for developed world cities is the supply of safe, clean water. A megacity will often have a demand for water greater than the supply. This means that water needs to brought in from other areas or other solutions need to be drawn up, such as a desalination plant. New York's water supply is 4.1 million m3 of drinking water per day.
Every person and business will produce waste, and the rubbish of a city combined is going to be huge. Much of this waste will end up going to landfill which is both expensive and wasteful. New York produces 12,000 tonnes of household waste every day, 17% of which is recycled, as well as 13,000 tonnes of waste from businesses: 90% is taken to landfill on river barges.

Challenges facing developing world megacities

Challenge Case Study - Mumbai
The level of housing simply cannot keep up with the rate at which the population is increasing. This leads to people resorting to building their own homes on any vacant land using scrap materials like cardboard, corrugated iron and plastic. Using theses scrap materials presents serious risks such as fire, flooding and landslides. Also, because these houses aren't built by professionals and because they're built on any empty land, there is also no clean water, electricity, rubbish collection or organised sewage disposal. All these conditions make it a perfect breeding ground for disease. Around 1 billion people or 35% of people in the developing world live in slums and it estimated that by 2030 this number will double to 2 billion people. 54% of people live in slums. The largest slum, Dharavi, has 800,000 people living in it. On average, people in Mumbai only have 4.5m2 of living space.
Roads in developing cities were never originally built to handle such large volumes of traffic they do today, because of this, the roads will often be very congested. The ownership of cars has also increased significantly adding to the problem of road congestion and air pollution. Serious levels of air pollution can cause various health problems as well such as asthma and bronchitis. Mumbai is a fairly compact city, with only 2% of people owning a car and 55% of people walk to work. Despite this, Mumbai is still one of the most congested cities on earth. 3,000 people die crossing railway tracks or falling off packed commuter trains each year.
Water supply & pollution
The UN estimates that 1 billion people do not have access to adequate supplies of water and 2 billion do not have adequate access to sanitation facilities. The lack of supply of safe water means that people have to find alternative sources which may mean for some people having to drink from pools of water on the ground. Drinking water like this which is most likely polluted accounts for 2 million deaths worldwide each year. Open water also attracts mosquitoes and provides a breeding ground for malaria. Mumbai suffers from severe water shortages. Due to the old, leaking pipes, 650 million litres of water is lost each day. Some slum dwellers spend up to 20% of their money on water.
The Informal Economy
Unemployment and underemployment are both major problems in the developing world. Most people are unable to get permanent, full-time jobs so they often find themselves working on a street corner doing some informal work like shining shoes, giving haircuts, selling water or carrying luggage. The informal sector in Mumbai employs 68% of Mumbai's workforce, the large majority of these workers coming from the slums across the city.
Air pollution is a serious problem for the people living in developing world megacities. The use of old cars emitting dirty and harmful fumes and factory pollution not being regulated are just two of the main reasons why pollution is so high. It's not just air pollution, pollution in water ways from sewage and industrial waste is also a problem. The World Health Organisation's recommended limit for PM10 (a particulate matter which can cause asthma, bronchitis and even cancer) is 20 micrograms per m3 however in Mumbai, levels of PM10 are around 132 micrograms per m3 which dangerously high.

Managing challenges in the developed world - London, UK

Reducing cities' eco-footprint
London is one example of a city in the developed world making efforts to reduce its eco-footprint. Some ways they have done this is through:

Sustainable Transport London has over 2,600 hybrid buses and are introducing around 3,000 Ultra Low Emission buses.
Low emission zones encourages the most polluting vehicles to become cleaner
Increase recycling Many councils around London offer recycling services for their residents making it easy for them to recycle

A key case study within London is Beddington Zero Energy Development (BedZED) which was built as a solution to the unsustainable lifestyle we all are currently living. Some of its key principles are:

  • It encourages people to travel around by public transport, cycling and walking rather than taking the car.
  • Only using energy from renewable resources generated on site
  • All of its houses are energy efficient. The houses face south to maximise solar gain, windows are triple glazed and have high thermal insulation
  • Rainwater is collected and reused on site. Appliances are water efficient and the taps are low flow taps reducing water use.
  • All building materials used to build the site were selected from renewable or recycled sources with 35 miles of the site, reducing transportation pollution and energy usage.
  • Water, gas and electricity meters are all at eye-level so the residents can keep track of how much they are using and keep their use to a minimum.

As a result of all these efforts, BedZED's eco-footprint is considerably less than the average UK resident. For example, their hot water consumption was 57% less and their electricity use was 25% less than the UK average.

Sustainable Urban Transport

A major problem in world cities is transport

London is a good example of where all these things are happening on a daily basis. It is also an example of a city trying to address these problems. Transport contributes 17% to London's eco-footprint and so they are trying to make transport more sustainable. To do this they have to

London aims to reduce its CO2 emissions by 60% by 2025, partly by improving transport. Ways they are doing this are:

Congestion Charging

Cleaner Buses

Click here to learn more about how Transport for London are working to improve buses.

Encouraging Bicycles

Quality of life in developing world cities

Managing social and environmental challenges is one the main difficulties cities face. There are however a number of different ways to improve the quality of life for ordinary people:

Urban Planning - Curitiba, Brazil

Self-help schemes - Rocinha, Rio de Janeiro, Brazil

Mumbai, India

Developing a less polluted city: Mexico City, Mexico

Mexico City is one of the world's largest city with 21 million people, and faces 3 major environmental challenges: air pollution, water pollution and waste disposal.

Air Pollution

In 1992, the UN described Mexico city as the most polluted city on the planet. In 1998, the UN then named Mexico City as 'the most dangerous city in the world for young children'. The pollution was so bad that it caused over 1,000 deaths and 35,000 hospital admissions in 1998. The main sources of air pollution were from vehicle exhausts, emissions from factories and power stations. The situation was made worse by the city's geographic location. Mexico is situated in the crater of an extinct volcano meaning that the pollution can't escape and becomes trapped.

Tackling the problem

Measures Advantages Disadvantages
Providing funds for spare parts to maintain the city's buses Reduced air pollution
Bus services are more reliable
Parts are expensive
Buses are already old and will eventually need to be replaced
Changing the legal formula of petrol and diesel Reduced the amount of pollutants released into the air Expensive
Money could be spent on less polluting engines which
Banning drivers from using their cars on one day per week Reduced traffic
Reduced air pollution
Drivers avoid it by buying two cars
Building a new underground train line Reduced air pollution
Reduced commuting time, 150 minutes to 78 minutes
Expensive, would cost $2 billion
More larger, efficient articulated buses Fewer buses needed so less air pollution
Reduced commuting time
Expensive, but not as much as a new underground line
Bike share scheme Reduced congestion and air pollution Not practical for people with a long commute

Water Supply and Pollution

Mexico City faces serious challenges regarding its water supply and pollution. Population growth has meant more water is needed for the city and getting this water has led to over-exploitation of the underground water supplies. The city's response to the lack of water for many years has been to pump water up from the 514 underground aquifers, however this has now having serious consequences. The land surface of the city is now sinking at the rate of 9cm per year, causing water and gas pipes to fracture and road to crack, as the aquifers begin to dry up. The increasing demand and use of water has put more pressure on sewage-treatment plants which cannot cope with the volume.

Measures Advantages Disadvantages
Build more sewage treatment plants Will reduce water pollution Expensive to build
Conserve more rainfall in underground tanks and cisterns Would reduce the dependency on underground aquifers and the amount pumped from aquifers Simple tanks in homes could be easily polluted by insects and animals
Recycle more water Would reduce the dependency on underground aquifers and the amount pumped from aquifers Limit to how much can be recycled
Pump more water from deeper wells Help meet demand in the short term Very expensive
Contributes to the subsidence in the city

Waste Disposal

Mexico City produces 13,000 tonnes of rubbish each day, but only 9,000 tonnes can be removed by the current waste collection system. This results in the excess rubbish being dumped on open ground, waterways, streets and drains where it causes more problems by clogging up the system. In 2012, the biggest waste dump in the city was closed but no alternative was suggested leading to a massive rubbish mountain and neighbouring towns refusing to take their waste.

Measures Advantages Disadvantages
More recycling Reduces waste that goes to landfill Many people will be slow to adopt recycling
Build a new plant to burn waste Reduces waste that goes to landfill
Reduces water and air pollution
Will generate electricity
Potentially could add to air pollution
There are better uses for the waste material
Encourage more composting Reduces waste that goes to landfill
Reduces air and water pollution
Limit to how much can be composted
Burying it in new landfill Improve the problem in the short term Potentially could add to air and water pollution
Not a viable long term solution