A recent peer-reviewed article published in PLoS ONE is raising the alarm bells about urban growth. The report entitled, â€œA Meta-Analysis of Global Urban Expansionâ€ suggests that the explosive growth in cities around the world over the next twenty years will pose significant risks to people and the global environment.
By 2030, urban areas will expand by 590,000 square miles (an area the size of Mongolia) to provide for 1.47 billion more people living in urban regions. However, most of this urban expansion will be occurring in the developing world, including India, China, and Africa. The articleâ€™s lead author, Karen Seto, worries that as a result, development will occur in places that are â€œbiologically diverseâ€ such as coastlines, savannahs, and other vulnerable places.
In China, urban growth has become particularly pronounced in recent years due to the growth of the middle class. As their income levels increase, they demand bigger and better homes, which thus consume large areas of natural habitat.
In contrast, urban growth in countries like India and Africa has been a result of population increases and rural-to-urban migration. However, urban growth in these largely impoverished places has led to the proliferation of large-scale slums, characterized by unsafe living conditions, high crime rates, precarious living arrangements, and poor access to water and electricity. The social consequences of such urban expansion in the developing world have been studied by urban geographer Mike Davis in great detail in his seminal article (and follow up book) â€œPlanet of Slums.â€
Without a doubt, such unprecedented human expansion over the past 100 hundred years has fundamentally changed humansâ€™ role in the natural environment. As I discussed in a previous article, we are now living in the Anthropocene. And with a potential 9 billion human inhabitants on the world in forty years, we need to seriously examine the impact our cities are having on the Earth.
The PLoS ONE article was drawing attention to the consequences of urban expansion. Expansion in this case suggests â€œhorizontalâ€ urban growth which requires large tracts of consumable land.
In order to make way for 9 billion more people, we need to shift away from horizontal growth and focus on vertical urban growth â€“ that is growing higher into the air with higher density living and working arrangements.
By concentrating growth in such a way, we will be efficiently using our land resources and allowing people to live more sustainable lives.
However, ensuring such growth in the developing world and China could be a challenge.
What do you think are some ways we can accomplish sustainable urban growth?
Image credits: NASA.Â Chengdu, 1990 (above), Chengdu 2000 (below)