When we look at the growth of cities, we’re also directly talking about the growth of populations, so let’s go through some population projections, and understand how big these population numbers actually are.
Today the world is 50% urbanized. In other words, cities are home to over 50% of the world’s population. This urbanization trend is expected to rise to 70% by the year 2050. The 2015 World Urbanization Map here shows current urbanization levels in countries around the world based on the United Nations Population data. Some of the highest levels of urbanization, in the range of 80-100% urbanization is shown in red on the map, and appear in most of North America, eastern parts of South America, Australia and parts of northern Europe, and one point in Africa – in Gabon actually. Some of the lowest levels of urbanization, in the range of 0-20% is shown in dark green on the map, and appear in parts of Africa and a scattering in southern parts of Asia. Looking out beyond 2015, researchers have come up with population forecasts to determine when and where populations will be increasing, and cities will be growing.
Looking to the future, looking to 2050 and 2100, Hoornweg and Pope make some population predictions for the world’s 101 largest cities in the 21st century. They use 2010 as their baseline year, and make predictions to 2100, by taking an approach to include all urban areas expected to have more than 5 million people before 2100. In 2010, 757 million people resided in the 101 largest cities – 11 per cent of the world’s population.
Their predictions are based on the National Centre for Atmospheric Research’s socioeconomic scenarios of development, known as the Shared Socioeconomic Pathways (SSPs). For various levels of sustainability and global development, the three basic shared socioeconomic pathways shown here are:
The first, SSP1, demonstrating Sustainability, where the world makes relatively good progress towards sustainability, and demonstrated achievements of development goals, while reducing resource intensity and fossil fuel use. Some of the characteristics of the world under this scenario appear as rapid development of the low-income countries; reduced inequality; rapid technology development; and an open and globalized economy). By 2100, the world population will be 7 billion at 90% urbanization.
The second, SSP2, demonstrating Middle of the Road, where the assumptions here follow the status quo including current trends in urbanization, population growth, technological change and economic growth. The estimated population by 2100 is 9.5 billion at 80% urbanization.
The third, SSP3, demonstrating fragmentation, where urbanization is slow. What this looks like in high-income countries is a low population growth, particularly of an ageing population, and slow economic growth and technological changes which reduce the incentives for urban expansion. In the developing regions, there is rapid population growth, particularly in rural areas, causing significant land use change and environmental degradation.
The “best fit” projections are made for each city individually, using global urbanization forecasts.
By 2100, the population is estimated at 6.9 billion and prosperous, or 13.1 billion, with pockets of extreme poverty, depending on which pathway we will be following. For the 101 largest cities, that could mean 1.6 to 2.3 billion, that’s 15% to 23% of the world population residing in the 101 largest cities.
The main assumptions for population growth in the three SSP scenarios are based on demographics pertaining to fertility, mortality, migration; in addition to education rates.
These rates are categorized for low-income and medium-income nations based on fertility rates, and for the OECD (Organization for Economic Cooperation and Development) and high-income nations. The rates and trends are derived from forecasts and analyses by organizations and global networks such as the World Urbanization Prospects for birth rates and mortality, and the International Institute for Applied Systems Analysis for education rates, and country populations. Population predictions for planning horizons beyond 2050 are not without uncertainties, but this is the best that can be done given the data currently available.
The rankings of the top ten cities will change over time. But before I show you the rankings over time and into the future…
Here is a list of the top 10 cities in 1800, notice many Chinese and Japanese cities. Beijing is in the lead, and other Chinese cities are Guangzhou and Hangzhou. Japanese cities here are Tokyo, Osaka and Kyoto. And in 5th, 6th and 7th place there are other cities in Europe, which are Istanbul, Paris, and Naples in that order.
In 1900, we find mostly European and North American cities. Most of the cities we saw earlier have disappeared from this list with the exception of Paris and Tokyo. In the number 1 spot there’s London. Other European cities include Berlin, Vienna and Manchester. American cities here are New York, which holds the number 2 spot, and Chicago, and Philadelphia. And one more to complete the top 10 is St. Petersburg in Russia.
In 1950, New York and London still in the top two spots, and the emergence of Chinese cities again with Shanghai, and newly appearing South American cities with Buenos Aires, and Indian cities with Kolkata. Notice Paris and Tokyo are still on this list. New cities appearing in a wide range around the world here are Moscow, Chicago and Ruhr.
Now in 2006, and for arguments’ sake let’s say 2006 is the most recent present day rankings, notice Tokyo is still on the list. Only New York and Mexico City appear from the North American cities, and now the list is mainly Indian, and other Asian cities in the south, and South American cities. Indian cities are: Mumbai, Delhi, Kolkata. Other Asian cities in the south are Dhaka and Jakarta. South American cities here are Sao Paulo and Buenos Aires.
As we look to the future, in 2050, New York and Mexico City are at the bottom of the list, and the majority of the list shows more Asian cities, and the first appearance of African cities – Lagos and Kinshasa. The Asian cities in ascending order starting with Mumbai in the lead, followed by Delhi, Dhaka, Kolkata, Tokyo, and Karachi. 2050 is far out into the future, and therefore predicting population growth of cities not without uncertainties. Because much of today’s infrastructure and resource development investments have planning horizons beyond 2050, it makes a lot of sense to predict growth of cities and population even beyond 2050.
So, by 2100, the top ten are 5 African cities and 5 Asian cities, The five African cities are Lagos in the first spot, followed by Kinshasa and Dar es Salaam in the 2nd and 3rd spots, and Khartoum and Niamey. The five Asian cities are mostly Indian cities actually – Mumbai, Delhi, and Kolkata. Other Asian cities on this list are Dhaka and Kabul. Humanity is at a very rapid urbanization path that as we saw primarily started in 19th century Europe, the Americas and parts of Asia, and will likely be prominent in Africa at the end of this century. As Hoornweg and Pope put it at the end of their population projection analysis, is that urbanization is a powerful driver of sustainability: as affluence increases, basic services can be provided more efficiently in an urban setting. Urbanization also tends to provide greater wealth, particularly to the urban residents. Many of the more dominant challenges of urbanization have their roots in the purchasing habits of these affluent urban residents. Sustainability in the 21st century will largely be about the purchasing habits and infrastructure development of the world’s next 2.7 billion urban residents.
Shifting now to Africa. Africa’s projected city growth is striking. For example, among numerous Africa cities in Tanzania, Niger, Kenya, Malawi, Uganda, Zambia, Somalia, Chad, Mali, Senegal, (I’ll keep going) Mozambique, Burkina Faso, Madagascar, Rwanda, Guinea, Liberia, Ghana, Togo and Cameroon, none of these countries had a city that was ranked among the largest cities in 2010, yet all have cities that are projected to have at least one appearing in the 2100 rankings. Today, almost 10% of the global urban population lives in African cities. By the end of this century this ratio will increase to more than one third of the world’s total – this is adding 2.2 billion residents in Africa. Just seven of the world’s 100 largest cities are in Africa, by 2050 that will increase to 20, and by 2100, over 30 of the world’s 100 largest cities are expected to be in Africa. With almost one third of the global population on the African continent, supporting these populations will have implications for sustainable development, resource consumption and quality of life. As goes Africa, so goes the world.
Let’s take a look at the population numbers and city rankings as they pertain to African cities. The number of African cities with over 5 million in population will grow from 10 in 2010 (about 10% of global share) to 67 in 2100 (representing 43% of such cities globally). The table here shows the top African cities located in the world’s top 20 largest cities and their corresponding populations by the year 2100. Starting from the top, we have Lagos, Kinshasa, Dar es Salaam, Khartoum, Niamey, Nairobi, Lilongwe, Blantyre City, Cairo, Kampala, Lusaka, Mogadishu, and Addis Ababa. You can see here that five of the world’s largest ten cities will be in Africa, each with more than 50 million residents. Or looking at it another way, 13 of the top 20 cities will be in Africa. In 2010, only one African city (Lagos, Nigeria) was among the world’s 25 largest cities. By the year 2050, the populations of Dar es Salaam, Khartoum, Cairo, Lagos and Kinshasa will range from 16 to 35 million. Managing cities in excess of 50 million will be an overwhelming task, particularly when seeing how underdeveloped and underserviced they are today. Niamey in Niger for example is projected to grow from under 1 million inhabitants today to 56 million in 2100. Lagos in Nigeria will be the world’s largest city with 88 million in 2100, contrasted to its current population of nearly 11 million today. The city population projections presented here in the research by Hoornweg and Pope, are driven by national populations from shared socioeconomic pathways and estimated urbanization rates. They claim that these estimates will be further impacted by regional economies, resource availability, conflict, and potential geophysical and climate disasters. The numbers show how sustainable development through the largest cities can impact overall global sustainability trends. In the next few decades, the development of sustainable cities will be essential for global sustainability, and the case for Africa is made even clearer.
References:
Hoornweg, D., and Pope, K., 2017. Population predictions for the world’s largest cities in the 21st century. Environment & Urbanization, 29(1): 195-216.
Hoornweg, D., Sierra, K., Sanio, M., & Pressnail, K., 2014. Meeting the Infrastructure Challenges of African Cities. In: International Conference on Sustainable Infrastructure, Creating Infrastructure for a Sustainable World: 2014. Crittenden, J., Hendrickson, C., & Wallace, B., eds. pp. 471-481. https://ascelibrary.org/doi/10.1061/9780784478745.042
Image: Orthographic map of Africa by Martin23230 is licensed under CC BY-SA 3.0 on Wikimedia Commons.
https://en.wikipedia.org/wiki/Africa#/media/File:Africa_(orthographic_projection).svg
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