With rising urbanization, urban land area is expected to increase to 80 per cent globally between 2018 and 2030. But if cities spread outward instead of upward, these can worsen spatial inequalities and create massive economic and environmental strains.
Cities around the world are growing fast, increasing the demand for urban land. But while wealthier cities in North America, Europe and East Asia are growing vertically through taller buildings, cities in sub-Saharan Africa and South Asia are growing mainly outward – and this could push them into crises, warn researchers from the World Resources Institute and Yale University, who analysed growth partners for 499 cities using remote sensing.
In their new report, Upward and Outward Growth: Managing Urban Expansion for More Equitable Cities in the Global South, the researchers outline the dangers of horizontal, unmanaged urban growth. These include greater social inequality in urban peripheries and higher municipal costs of providing public services such as roads and drainage outside city centres.
There is also a dangerous environmental impact: the demand for urban land comes at the expense of prime agricultural land, resulting in food insecurity and vulnerability to climate events such as flooding. These impacts are compounded by the fact that most of the outward growth currently underway in Africa and South Asia is unplanned or informal.
Fortunately, some cities are already taking action to proactively manage these challenges – and could serve as an example to others. For example, cities in Mexico, Brazil and South Africa are directing new development to already well-service and connected areas, while those in Colombia, South Korea and India are partnering with public utilities and private companies to help finance vertical development.
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