The BBC website has a visualization of the growth of global cities showing the growth of cities of more than 5 million people as part of their coverage of the World Urban Forum.
The coverage includes other interesting articles, such as a multimedia profile of a few of the million people who live in the slum of Dharavi in downtown Bombay, and Finding green in the concrete jungle, a look at how air pollution in cities compares in rural areas.
Fuel use, intimately connected to urban pollution and greenhouse gas emissions, demonstrates exquisitely the problems in trying to compare the ecological footprint of the rural and urban dweller.
In 2002, the United Nations Development Programme (UNDP) focused much of its Human Development Report on China.
“Rural residents consume less than 40% of the commercial energy used by their urban counterparts,” it concluded.
Tokyo’s population and economy have grown while air quality decreased.
“However, if biomass [principally wood-burning] is included, the average person in the countryside uses nearly one-third more energy than a city dweller.”
So the rural resident apparently contributes more to global climate change than the urban citizen – but the equation hinges on how the energy is produced.
If “commercial energy” used in cities – principally electricity – is derived from renewable sources or nuclear stations, the urban dweller wins the eco-prize hands down. But if the rural citizen burns nothing but trees and always replaces them, he or she becomes “carbon neutral” and scoops the award.
In London and Tokyo, air quality has improved over the last 50 years. In Shanghai and Kuala Lumpur, it has gone down, though there are signs of improvement elsewhere in the developing world.
“It has happened in Delhi, for example, where there has been a huge improvement in air quality by substituting liquefied petroleum gas [LPG] for diesel in vehicles,” observes John Harrington.
“Partly it is just that as cities become richer they can clean their act up, but it’s also how vocal the middle classes become, which in India counts in a way it doesn’t yet in China.
The coverage also includes less interesting articles. One disappointingly boring, and strikingly disconnected from the other articles is a collection of perspectives on the urban world in 2050 from urbanization experts. Their views of 2050 seem to more represent cities today, rather than a global view of what cities could become.