In an interesting recent article on urbanization, The Economist noted:
A huge and growing number of people live somewhere like Mikwambe [“on the edge of Dar es Salaam”]. Between 2005 and 2015 the world’s cities swelled by about 750m people, according to the UN. More than four-fifths of that growth was in Africa and Asia; specifically, on the fringes of African and Asian cities. With few exceptions, cities are growing faster in size than in population. Lagos, the capital of Nigeria, is typical: it doubled in population between 1990 and 2010 but tripled in area. In short, almost all urban growth is sprawl.
Among other things, this suggests environmental and climate change implications. Urban sprawl, whether of the kind experienced in America in the middle of the 20th century or the sort taking place in today’s newly emerging cities, essentially depends on cheap transportation. Furthermore, low urban density is a poor match with public transport.
Countries all over the world may be persisting with urban design choices which will make decarbonization more difficult. As a corollary, if we succeed in fighting climate change, it may make large parts of these sprawling cities economically unviable.