Bethany Torr

In a very over simplified, and arguably unhelpful manner, Google provides this definition of urbanisation: “the process of making an area more urban”.

Nevertheless, let’s put some numbers to this definition. One-hundred years ago only 20% of the world population lived in a city. Factor in one industrial revolution, the emergence into the technological era and a massive increase in GDP per capita (wealth of people) and the result today? Over half of the world’s population live within urban areas.

This number is not set to remain here, however. In 2017, the global population size is ~7.5 billion and this is expected to increase to 10 billion by 2050. It is also expected by this date that over 75% of the world population will live in urban areas. It is expected that we’ll see for the first time, the majority of people in developing countries living within urban areas.


Image Credit: Wikimedia Commons

Whilst increasing world population is a driver in urbanisation. The greater availability of resources, wider job opportunities and higher salary pull people into cities. You only need to look at the number of graduate opportunities in London to know that cities pull people in this way.

Geoffrey West*, a physicist at the University of Cambridge, and colleagues identified that doubling the size of a city increases wealth, income, the number of available workers and creative people etc. by 15%. Essentially this equates to a 15% saving on all city infrastructure. This makes urbanisation increasingly attractive, especially for lower economically developed countries (LEDs).

On the surface, all of this makes urbanisation look desirable for increasing prosperity of countries and people. There are, however, a wide range of issues for both people and the environment that come alongside increasing urbanisation.

Beside the 15% increase in availability of people and wages upon doubling city size, a similar increase is observed in the amount of domestic and sewage waste. The major issue is that correct management of waste comes with a large price tag and for developing countries this cost can be too high.

Improper waste management may lead to issues with poor sanitation and disease. For example, during the 19th century when London’s population was dramatically increasing, there was a severe outbreak of Cholera in the Soho district. This was due to improper disposal of waste and excrement entering the water systems. This case, labelled the Broad Street cholera outbreak, was a large influence in increased investment into public health and improved sanitation in the UK.

There are also implications for the environment from improper waste management. Domestic waste that is not recycled is either placed into landfill sites or incarcerated. During the decomposition process, methane is released. A greenhouse gas that strongly contributes to global warming.

Leachate fluids are also produced during decomposition of waste. A term that refers to any liquid containing environmentally harmful substances. These fluids are a particular issue if the landfill sites are not properly contained, allowing the fluids to pass into water streams. This may alter oxygen content and be damaging to water species, as well as being damaging to the environment through evaporation and the water cycle.

The major environmental impact of urbanisation is loss of green space and natural habitats. The impact this has on the increasing atmospheric carbon dioxide levels is two-fold. A bigger city requires more energy and thus increasing the production of greenhouse gases from non-renewable fuel source. Additionally, as vegetation is removed for buildings, there is less atmospheric carbon dioxide taken up by plants and converted to oxygen through the process of photosynthesis. The potential loss of species through removing natural habitats is, also, a major issue.

The University of Sheffield are researching green roof technology designed specifically to overcome these environmental impacts of urbanisation. Extensive green roofs are composed of drought and weather resistant, small-growing plants, that require very little support from building structure. Allowing vegetation to be added to pre-existing buildings more easily than intensive green roofs, that are similar to normal ground landscapes, composing of trees and shrubs. The green roof technology aims to replace ground habitats onto rooftops, avoiding loss of species and reducing carbon dioxide levels within cities. The technology, also, has economic value by providing insulating properties to buildings.

The increase in urbanisation is happening so quickly that, in many places, the number of slums have also been increasing due to lack of available housings. These slums are formally known as “informal settlements” and pose huge health risks because of the lack of proper infrastructure, sewage and water systems and inadequate food storage. The overcrowding and lack of legal health and safety services are also likely to lead to increased violence, drug usage and negatively impact mental health.

While many countries are increasingly facing the struggles of urbanisation and major cities across the world are attempting to overcome pollution and climate change. Many pre-existing urbanised countries, such as the UK (90% of the population live in cities or towns), are seeing a greater movement in counter-urbanisation. With statistics suggesting that more people are attempting to move out of cities to the edge of urban areas instead.

The predicted increases in urbanisation and the impacts are most likely to be seen in African countries, where the 3bn increase in global population between now and 2050 will be concentrated.
*More from Geoffrey West about the maths of cities and corporations here.

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