A vegetable farm next to high-rise apartments in Hong Kong.
These high-rise apartments in Hong Kong are urban, but what about the vegetable farm beside them? Bobby Yip/Reuters

Experts at the European Commission assess the world as more urban than experts at the United Nations or New York University do. We need to resolve this debate.

It may be the one data point most commonly cited by urbanists: We live in a world that is over 50 percent urban. We crossed the majority threshold in 2008, and have since grown to 55 percent today. The world is projected to be 70 percent by 2050, and ultimately top out at around 85 percent or so a century from now.

But a new report released by researchers at the European Commission (EC) says the current level of global urbanization is much higher: It estimates the world to be 84 percent urban already. The EC research team, led by Lewis Dijkstra, used satellite images to assess the share of the world’s population that is urban. While traditional estimates from the United Nations and elsewhere find Asia to be 50 percent urban, the EC team’s analysis of satellite images finds it to be 90 percent; while the UN estimates Africa’s urban population at 40 percent, the EC research team finds it to be 80 percent.

The European Commission research team contends that these discrepancies stem from the ways the data is traditionally reported. The 55 percent figure comes from data that is self-reported by nations. The rub is that different nations use different definitions to identify what is “urban.” According to the EC group, about half of countries define urban based on a minimum population size threshold—85 percent of countries use a threshold of 5,000 people or fewer but other countries have dramatically higher requirements, like Mali’s 30,000, Japan’s 50,000, or China’s 100,000. Only a few countries use population density as a measure of urbanization.

Other definitions are even more detailed and highly specific. India classifies places as urban if less than a quarter of working-age men work in agriculture. And in some nations, political considerations muddle definitions further. For example, in some countries, once a place is classified as urban, there are requirements that it must host certain facilities, like courthouses or police stations. Governments may therefore avoid classifying places as urban simply to avoid shelling out for these upgraded public services. Take the case of Egypt, which has said that it is 43 percent urban every year since 1986, despite significant urbanization since then.

But, at least one other leading team of urbanists is not so sure about the EC’s numbers. A report by Shlomo Angel, a leading expert in global urban expansion at New York University’s Marron Institute of Urban Management, finds the 84 percent figure to be far too high, and contends that the conventional 55 percent figure is more on target.

Angel believes the density thresholds the EC team used to interpret the satellite images end up incorrectly classifying broad swaths of rural farmland as urban. Angel and company further ask how 84 percent of the world’s population is urban, when 37 percent of the world’s labor force is employed in agriculture. Angel believes the most effective way to gauge urbanization is not through population or density per se, but by looking at contiguous built-up areas of 100,000 or more people. The group plans to create its own new estimates of global urbanization in the future.

The EC team sees things somewhat differently. Dijkstra believes that Angel and company’s method of looking at built-up areas is skewed toward richer, more developed countries. “The amount of built-up area per capita is much higher in cities in developed countries than in less-developed countries, by a factor of 5 to 10,” Dijkstra wrote in an email. “As a result, this method has a big, built-in, rich country bias.”

The way we estimate global urbanization is not just a debate among researchers, it has huge import for strategies and policies we will use to address urban challenges in the future. If the world is 55 percent urban, the challenge may be to build new and better cities to accommodate the billions of new urbanites, as well as to retrofit and upgrade existing ones. If the world is already almost 85 percent urban, building new cities would seem less efficacious and the priority would fall to upgrading existing urban centers and settlements where people are.

To my mind, this debate illustrates the pressing need to develop better, more robust, more comparable, and more systematic data on cities and urban areas across the world, something I have pressed for for a long time. As an urbanist, it is troubling to me that our existing science cannot identify whether the world is 55 percent or 84 percent urban. This is a very, very large difference. I spoke to a wide range of experts on global urbanization about this discrepancy. They all believe we lack the data to make an accurate assessment to resolve this debate, and thus are unwilling to take sides. They suggested that we need new and better data, and that regardless, we should continue to develop strategies for upgrading and densifying existing cities and metro areas and for building new ones.

The research, data, and urban science we have on the world’s cities and urban areas is troublingly inadequate. If building better, more resilient, more sustainable, and more prosperous cities is key to our future global well-being, it is critical that we do much better.

CityLab editorial fellow Claire Tran contributed research and editorial assistance to this article.

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