City shapes and climate change in Africa

Africa is undergoing an unprecedented urban and climate transition; yet, given the right conditions, compact urban forms can encourage greater sustainability, resilience and liveability in the coming decades. Using novel techniques and newly available data, this report fills in existing data gaps by producing measures of compactness for 5 625 urban agglomerations, along with other urban form attributes. Even though urbanisation is often unplanned and uncoordinated, a promising trend has emerged: very large cities (of over 4 million inhabitants) are more compact, discounting the population effect, on average, than larger (1 million to 4 million inhabitants) and intermediate cities (50 000 to 1 million inhabitants). Moreover, less compact agglomerations tend to have smaller buildings, flat, low skylines, less complete centres (reflecting a less optimal use of space) and polycentric patterns (i.e. multiple centres, rather than a single, monocentric city). This report analyses the consequences of less compact agglomerations for sustainability and liveability. The disadvantages include higher energy demand, less accessibility to services and opportunities, less walkable urban landscapes and greater car dependency, in addition to higher outdoor air pollution. It also considers the potential trade-offs with resilience; for example, compactness can lead to a loss of green space and an increase of urban heat island effects. The report offers opportunities in the coming years to single out potential areas of action for resilience, as well as for monitoring and evaluating progress.