Insurgentes Corridor, Mexico City. Photo credit: World Resources Institute Ross Center for Sustainable Cities. Copyright © 2007 Centro de Transporte Sustentable

In the future, heavily populated cities may benefit the environment

Grappling with growth

By Koen Kusters, a regular contributor to Landscape News.

There is hope for a “renaissance of nature,” according to a recent article in the Journal BioScience. In a hundred years, the authors predict, the conditions for nature will be much better than they are now, primarily due to ongoing urbanization. The task for the coming decades is to make sure not too much gets lost in the interim.

In the article, Eric Sanderson, Joe Walston, and John Robinson of the Wildlife Conservation Society (WCS), argue that the trends that contribute to environmental destruction—population growth and increased consumption—will in fact lay the foundation for future conservation. Urbanization will have a key role to play in this process.

It seems counter-intuitive. After all, environmental impact usually increases with urbanization, because people in cities tend to consume more meat, processed foods and to produce more waste. But appearances can be deceptive.

Drawing from scientific research in demographics, economics, sociology and conservation biology, the authors conclude that cities offer the solution to the world’s environmental crisis.


Conservationists are not known for their positive outlook on the future. Despite decades of conservation efforts, the decline of habitats and biodiversity continues, due to a seemingly unstoppable growth of population and consumption. In this context, conservation has become synonymous with efforts to slow down the decline of biodiversity.

The authors of the BioScience article, however, refuse to succumb to the “jeremiad, bickering, and despair” that they say characterizes many 21st century conservationists. Instead, they predict that a century from now, three conditions that are vital for lasting biodiversity conservation will be met: the world’s population will stop growing, very few people will live in extreme poverty, and most will live in cities, where new ideas and innovations flourish.


Global population started accelerating in the second half of the 18th century because of reduced mortality rates and increased fertility. Today, the world has around 7.6 billion people, and this number will continue to grow. The United Nations projects a population of 11.2 billion by 2100, implying an enormous increase in the demand for natural resources.

Currently, 55 percent of the world’s population lives in urban areas, a proportion expected to increase to 68 percent by 2050, according to new figures. Projections show that urbanization combined with the overall growth of the world’s population could add another 2.5 billion people to urban areas by 2050.

However, despite the patterns of the past, demographers agree that the human population will not grow indefinitely. After reviewing demographic projections, Eric Sanderson and his co-authors expect that the peak will be reached around 2100, after which the population is likely to stabilize or could even start declining.

For nature to benefit, the ideal scenario would be to accelerate the process towards population stabilization. This does not require draconian population policies, the authors say.

Instead, under the right conditions, the social dynamics of cities will ensure that the average family size decreases. In cities, women will have more opportunities to earn income, more options for education, and better access to contraception, which will lead to greater autonomy and more control over their reproductive lives, the authors write.

Moreover, living in a city takes away the incentive to produce large numbers of children, as the costs of sustaining a large family are higher, while child mortality is lower.


Urbanization not only results in lower fertility rates, it also increases wealth. This is the second virtue of cities highlighted by the article. Since the industrial revolution, the world has witnessed unprecedented economic growth and poverty levels are expected to continue declining. Urbanization is one of the main drivers behind this remarkable progress, say the authors.

Cities offer more opportunities for work and education, which results in higher per capita incomes. Moreover, growing cities also have spillover effects, as they function as markets for goods from the surrounding rural areas.

But, doesn’t increased wealth also increase pressure on nature? Here Sanderson and co-authors point at the non-linear relationship that exists between wealth and consumption. After basic human needs have been fulfilled, increased income does not result in an equal increase in consumption.

Also, as people in cities depend entirely on the market place for their consumption, they are more sensitive to price signals. By installing policies to make sure that market prices reflect the environmental costs of production, governments can effectively decrease the environmental footprint of urban consumption.


A third way in which urbanization helps conservation in the long term is related to the role of cities as breeding grounds for new ideas and innovations. Cities have always been hubs for art, science and communication—they are places of creativity and intellectual progress.

This also concerns the development of ideas about conservation. A practical example is the rise of environmental awareness among urban citizens, with a growing number people that are willing to pay for “green” products.

Cities do not only provide new ideas, but also offer the conditions that enable people to act upon those ideas, mostly in the form of access to capital and connections. Most social movements originate in urban areas, including those that focus on nature conservation. Indeed, most of the world’s major conservation agencies were founded in cities.


In today’s world, increased use of natural resources and pollution are threatening the natural environment. Sanderson and his co-authors call this the “bottleneck period.”

They predict that this situation of extreme stress will last for another 30 to 50 years, during which conservation efforts need to focus on preventing biodiversity loss through the management of protected areas. After the bottleneck, they foresee a “breakthrough period,” when the human population stabilizes and pressure on the environment decreases. Time for nature to recover.

“The conservationist’s challenge is to keep the bottleneck open wide enough so that nature can survive to a breakthrough,” the authors write. “Therefore, the only sensible path for conservation is to continue its efforts to protect biodiversity while engaging cities to build the foundations for a lasting recovery of nature.”


If urbanization is key to conservation in the future, what does this mean for approaches to urban and rural development?

Part of the challenge is to make sure that cities provide a healthy and livable environment for all the people relocating to them, Eric Sanderson said.

“In the next 50 years, we will have to drastically expand existing cities and build many new ones,” he said. “We know it is hard to change a city after it has been built, so we better do it right the first time. It means we need visionary planners, who anticipate growth.”

Questions concerning rural development are equally complex, he added. “It all depends on the circumstances. In areas with rapidly growing cities, intensification of agricultural production may be required, to ensure sufficient food production. In places where populations are stable or declining, rural areas could be used for restoration and ecological farming to complement the protected areas.”

Article tags

citiesclimate changedevelopmentenvironmentpopulation growthurban growthurbanizationWildlife Conservation Society



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