Megacities: Environmental Friend or Foe?

A paper recently published in Proceedings of the National Academy of Sciences led by Chris Kennedy, a professor of civil engineering at the University of Toronto, sheds further light on the assumption that megacities are inherently sustainable. The researchers looked at 27 of the world’s largest cities and analyzed their “urban metabolism” — the flow of energy and materials through the city. They found that while these “megacities” (cities of 10 million people or more) account for almost 7 percent of the world’s population, they also consume 9 percent of its electricity, 10 percent of its gasoline, and produce almost 13 percent of global waste. So what happened to the efficiency that we are told is an inherent result of density?

It turns out that while density does equal efficiency, “megacity” does not necessarily equal density. Megacities do encompass those places that we typically associate with dense and culturally vibrant urban centers: New York City, Tokyo, London. But what’s not often taken into account is the fact that to keep them running, these cities also require surrounding areas such as industrial lands, ports, suburbs. In other words, the environmental benefits of a city’s dense urban core can be outweighed by the resource-inefficient, yet essential, areas on its periphery. They are, in fact, two sides of the same coin.

An area of focus that Kennedy’s research didn’t explore, but which potentially has an impact on resource use, is the psychological impact that increased urbanization has on sustainability. As people retreat from rural areas into cities, their interaction with nature also decreases. This is particularly true for the developing world. National Geographic’s annual Greendex Survey which measures nations’ consumption habits and attitudes, shows that people who are more connected with the environment demonstrate more sustainable behaviour; the more urbanized, the more unsustainable the behaviour. As author George Monbiot points out, this leads to a vicious circle: the richer we are, the more we consume, the more harm we do to the environment, the less we empathize with the natural world, the more we try to fill the void by buying more stuff.

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