Sustainable Cities Colelctive article titled "Mesmerizing Visualizations Document Pace of Urban Expansionis" shows rapid urban growth of six global cities (Paris, Chicago, tel Aviv, Mexico City, Sao Paulo, and Johannesburg).
“Urbanization stirs up all kinds of emotions about rights and inhumane conditions, but we decided to take a scientific approach to discover the scope of it,” said Anthony Flint, Lincoln Institute of Land Policy, at the Urban Thinkers Campus, an event organized by the Municipal Arts Society (MAS), New School, University of Pennsylvania, Next City, Citiscope, and 15 other organizations in advance of UN-Habitat’s conference on the New Urban Agenda in Quito, Ecuador, next year. To make better sense of the historic rate of urbanization, the Lincoln Institute of Land Policy put together an open and accessible Atlas of Urban Expansion covering 120 cities, with data built on historical maps, censuses, and satellites that quantify urban growth from 1900 to 2000. For 30 cities, the Institute went as far back as 1800. Working with Schlomo Angel of the Urbanization Project at the New York University Stern School of Business, they then turned the data for these cities into a set of mesmerizing visualizations.
The visualizations show all cities exploding from humble beginnings into engorging megalopolises. The rate of urban expansion, particularly over the past three decades, has been incredible, with millions of rural migrants moving into cities in Asia, Sub-Saharan Africa, and Latin America.
Watching visualization after visualization, it’s clear that Geoffrey West, a scientist with the Santa Fe Institute, was correct when he said cities are like vast organisms that grow based on their own metabolic rate. Consuming vast quantities of resources — land, water, minerals — they expand until there are no more resources, and then will perhaps shrink and die.
Some of the urban forms expand in a somewhat orderly manner, Flint said. In these cases, growth has been corralled into corridors and grids in a more sustainable way.
Flint said the data and visualizations show that “we need to be realistic about urban land. Cities have to plan ahead in terms of what they will need in 50 years. Even at high densities, we’ll still need a lot of land.”
The next steps for the Institute are to overlay some new data layers, so they can further define the character of urban expansion, for example, deciphering whether an area is a slum or not based on the formations of the settlement. They also want to figure out which areas of the city are affordable, but that will require “boots on the ground.”
And for the upcoming UN-Habitat meeting in Quito, which will create a New Urban Agenda, a 20-year development plan for the world’s cities, the Institute wants to create a “projected urban growth atlas,” that will show how the expansion of cities will look over coming decades.
This is a crucial undertaking because by 2050, the world population will hit 9 billion and some 6 billion of those people will live in cities. As Flint said, “60 percent of the cities that will exist in 2050 don’t exist now.” But unless steps are taken to design future cities better — planning ahead for grids, transportation systems, parks, and open space — many billions of people will still be living in slums with few rights in inhumane conditions.