This aerial view of Hanoi, Vietnam, clearly shows areas of decreasing density between the city and the countryside, making it hard to define the limits of the "urban" area.
In everyday usage, terms related to human settlements have vague, shifting meanings. What one person might describe as a small ‘city’ might be a ‘town’ or ‘village’ for someone else; one person’s ‘megacity’ might be a cluster of cities from a different perspective. Similarly, we can usually identify areas that are clearly within a city and others that are outside it, but there is usually a peri-urban area of intermediate density that usually lies between the two, making it hard to define a clear city limit. Formal administrative boundaries may have historic or political meaning, but are rarely aligned with the physical or economic extents of the urban area.
What exactly is a city? It depends who you ask
It turns out there is no standard international definition of an ‘urban’ area or ‘urban’ population. Each country has its own definition, and collects data accordingly. The statistic that 50% of the world’s population is urban is arrived at simply by adding up these incomparable, and sometimes conflicting, definitions.
When we think of urban expansion in the 21st century, we often think of ‘sprawl’, a term that calls to mind low-density, car-oriented suburban growth, perhaps made up of single-family homes. Past studies have suggested that historically, cities around the world are becoming less dense as they grow, which has prompted worries about the environmental impacts of excess land consumption and automobile dependency. A widely cited rule of thumb is that as the population of a city doubles, its built area triples. But our new study on urban expansion in East Asia has yielded some surprising findings that are making us rethink this assumption of declining urban densities everywhere.
- population growth
- sustainable urbanization
- East Asia urban expansion
- population density
- Urban Development
- East Asia and Pacific
- Lao People's Democratic Republic
- Taiwan, China
- Korea, Democratic People's Republic of
- Korea, Republic of
Cities have been experiencing a moment in the cultural spotlight in the last few years. There is more discussion and even celebration of cities than ever before. Newspapers and magazines are starting websites dedicated to global urban issues, university researchers and technology companies are turning their attention to ‘smart cities’, and there are even popular documentary movies, reality shows and musicals all about city planning. India, still mostly rural, has just elected a new Prime Minister who promises urban redevelopment and ‘new-age cities’, and it is no longer shocking to hear that China's proposed urbanization budget runs in the trillions of dollars.
Why has this urban moment come about now? Several trends, some in the developing world and others in wealthier countries, seem to have converged lately. It is interesting to step back and examine these trends, before thinking about where we go from here.
If you go to a conference on cities and climate change, you inevitably hear the statement that “countries talk…but cities act”. This message was loud and clear at the C40 Cities Climate Leadership Summit in Johannesburg last month, where a new report released by the C40 and ARUP detailed the 8000+ initiatives that C40 member cities are undertaking to either reduce GHG emissions or increase their climate resilience. Since the first such report came out in 2011, more cities are reporting on their efforts, and those reporting are doing ever more, expanding the array of initiatives they have launched.
Urbanization is the most powerful force shaping the planet today. This can be good news as urbanization is the best bet we have to meet our global poverty reduction targets. Cities generate our wealth, our culture, and our innovation. This is also bad news since cities generate the lion’s share of the world’s GHG emissions, and cities are responsible for most of the planet’s current decline in biodiversity. Cities also generate solid waste; lots of it and the amount is growing fast.
‘Peak waste’ – that point in time when all the waste from all the cities finally plateaus around the world, and then slowly starts to decline, is not on track to happen this century. Estimates are that it will peak at three-times today’s current waste generation rate. Peak waste is an excellent proxy for humanity’s cumulative global environmental impact; therefore we are on track to triple today’s overall global environmental impact. Our ‘assault on the planet’ will start to subside on the other side of peak waste. Therefore we must move peak waste forward and reduce its intensity when it finally does arrive.
Thoughts on urban growth from Kiel to Nairobi
I’m writing at the end of a long, dusty mission, after numerous plane, train and car journeys. In fact, 1/7th of my time has been spent on being transported from one city to the next; this gave me plenty of time to marvel at the diversity in city structures.
The first stop was Kiel, Germany, where I spent a few hurried days with academics, government officials, private companies and journalists, discussing solutions for pressing problems in trade and clusters and their impact on poverty and inequality. A city of around 280,000 residents, Kiel is small, about as dense as Dublin, and well-linked with the rest of Germany and Europe. It is one of multiple core-municipalities that form a system of cities around Hamburg along with Lübeck, Bremen etc. The train from the airport was relatively painless, and travel within Kiel (to shop for fresh bread and herring) consisted mostly of short walks.
This post was originally written for the Collective Solutions 2025 blog, a forward-looking study and collaboration platform to explore how the World Bank and similar multilateral institutions can best support developing countries to meet long-term sustainable development challenges in a post-2025 world. Read more about the study and join the collaboration site here.
I don’t particularly like cities. I’m a country boy. But I have lived in cities for the last 35 years; 10 in Bangkok, 15 in Manila, and 10 in Washington, DC (though DC might be called a town if it were in India or China). In the 1990s, I led work on environmental investments in east and south Asian cities. Most of the cities I worked in were severely “under-infrastructured and under-serviced,” and because many of them are built on coastal zones, this was particularly pronounced when it came to low-lying slums, drainage and sanitation. The heaviest price tag was often for drainage and flood control. During those years, I often wondered if and how the city and country leaders would ever catch up on infrastructure needs with the growing urban populations. Many have done well—while others are in worse shape now because they haven’t been able to meet the human tide.
Around 5000 years ago, the first cities emerged in Mesopotamia and the fertile valleys of the Tigris and Euphrates Rivers. Agricultural surpluses enabled a few people to start specializing in something other than agriculture. The farmer who now had extra grain could trade for a better spear or a winter fur coat. This specialization and the ability to trade goods and services is the basis of urbanization. And, there was enough food that the starving artist didn’t starve completely, so along with trade, culture emerged.
Cities grew at a modest pace until about 1800 when the Industrial Revolution took off in the UK and cities developed at staggering rates. Manchester, for example experienced a six-fold population increase from 1771 to 1831. London went from about one-fifth of Britain’s population at the start of the 19th Century to about half the country’s population in 1851. This rate of urbanization has not let up for the last two hundred years; in fact it is still accelerating. The growth of cities seen over the last two hundred years will now be repeated, but this time in just forty years.
When it comes to urban development, “green” has become the buzzword. Among the public, “green” is often understood to be synonymous with reducing greenhouse gas (GHG) emissions. In policymaking, “green” has much broader implications. It can range from preventing, treating, and abating pollution, to preserving and restoring environmental quality. It may simply be providing basic urban services which improve the cleanliness of streets. Apparently, there are different shades of “green” — we could define interventions targeting global public goods as dark green and those focusing more on local public goods as light green. Among them, what is the right one for South Asian cities?
Practitioners and government officials from the region had intensive discussions on this question throughout a recent workshop on urbanization in Korea, organized by the World Bank in collaboration with the Korea Research Institute for Human Settlements.