As world population hits 7 billion, megacities pose growing risks

October 31, 2011

The world population has officially reached seven billion, according to the UN.  This historic landmark reminds us of the massive challenges, including here in Europe, created by an ever-increasing number of humans on the planet.

Growing populations are also driving another mega trend — urbanisation through migration.  In 1800, less than 3 percent of the population lived in cities (mainly in Europe), yet by the end of 2008, this had risen to more than 50 percent (much higher still in Europe), and there were 26 megacities (cities of 10 million or more inhabitants), including Moscow, Paris and London.

Despite the economic success of megacities, governments at every level are preparing for the growing risks that these massive urban centres pose.  For instance, will it be possible to continually meet the everyday needs of food, water and health, and also deal with the growing vulnerability of megacities to environmental stresses exacerbated by the effects of climate change?

There is already cause for some alarm. For instance, the 2003 heat-wave in Paris was so devastating because both the public and authorities were unprepared for dealing with such extreme weather conditions, which were exacerbated by building practices, especially the lack of air-conditioning.  Moreover, the tsunami in Japan this year forced Tokyo to re-consider its approach to nuclear power and to protecting its cities.

During the 21st Century, megacities in Europe and across the world will continue to grow, as will other large urban conglomerations, such as the Rhine-Ruhr and Po Valley, which have megacity features.  Energy demands will thus increase as supplies of food, water and resources for industries and infrastructure require energy for transportation.

The associated increased carbon emissions are contributing to global warming and pose their own climate risks.  In China, where people are being subsidised to move from the countryside, cities have grown by a factor of 2 in only 5 years. The local urban ‘heat island’ effect means temperatures are increasing about three times faster than the rate of temperature rise over global and national land areas.

The main risk for riverine megacities on coastal plains is their increasing vulnerability to rising sea levels and river flooding, such as those devastating Bangkok right now.  There will be further episodes such as the one in New Orleans six years ago when it was hit by Hurricane Katrina, without adequate protection and flood warning systems.

In at-risk countries, such as the Netherlands, researchers are preparing for these type of problems.  For instance, Delft University’s Hydraulic Engineering Department has been developing a state of the art early warning and monitoring system, including the effects of subsidence, to protect coastal communities.

The larger the urban area, the greater the damage that natural hazards can inflict; and increasingly it may be impossible to protect life and property even if there is a perfect warning system. As a recent hurricane in Houston showed, despite the known dangers from combined hazards such as winds and floods, there is now insufficient time to evacuate some cities safely, even highly developed ones.

So there is a pressing need for cities to develop emergency refuge areas. In some cases these may already exist.  For instance, Canvey Island in England still keeps its mound in case severe floods of the nature of 1953 return.

In most cases, however, refuges will need to be built from scratch.  Thus, engineers and planners are considering how to identify and design such emergency centres, whether outside or within buildings, and how these should be connected to the wider urban system, including transportation.

Training populations to use the centres effectively is also essential.  Refuges have successfully withstood cyclones and floods in Bangladesh and, unlike those in some other developing countries, have been used by vulnerable communities, because they could take their vital farm animals with them — without the animals they are destitute.

Emergency energy supplies for communities, which are essential for medical emergencies, should improve in future.  This is especially so using advanced solar power — effective even in cloudy conditions.

Because of the failures to deal with some of the recent hazards impacting on megacities, governments at every level are planning for multiple hazards and developing strategies for managing the range of environmental factors which could emerge. Moreover, other research teams are collaborating in construction of ‘system dynamics’ models for the operation of infrastructure, environment and socio-economic aspects of megacities.

These models resemble well-known computer programmes for global climate change and its interconnections to economic developments.  As with Delft’s coastal monitoring system, these will help cities to predict which hazards they face and help them decide how to prepare.

The London Mayor’s office is taking a particular interest in which policy options emerge as London continues to expand.  Meanwhile, several European cities are experimenting with air quality hazard indicators based on complex system models to appraise citizens about how the environment in their cities varies hourly and over the longer term.

What these models need is improved availability of relevant environmental and socio-economic data.  Here, international agencies such as the World Health Organisation and the World Meteorological Organisation, as well as national governments, need to collaborate with a wider range of organisations, and make maximum use of new media.  This will better enable data showing how people experience both rapidly occurring hazards such as tornadoes, and slower, but still deadly, phenomenon such as loss of crops from rising sea levels and salt penetration.

Fortunately, megacities have a global organisation for information exchange and collaboration called C40 Cities. The future agenda here includes enhanced inter-city cooperation on policies for dealing with hazards, and putting more pressure on national governments to assist, especially with finance and data, and strategic priorities.

Lord Julian Hunt is Visiting Professor at Delft University and Vice Chairman of Global Legislators Organisation for a Balanced Environment (Globe).  Professor Yuguo Li is Professor of Mechanical Engineering at the University of Hong Kong.

Image — Baby Cin gets a kiss from his mother Miran shortly after being born at Avista Adventist hospital in Louisville, Colorado near Denver at 2:41 a.m. local time October 31, 2011. REUTERS/Rick Wilking


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Interesting piece. It contradicts the argument that centralized, urbanized populations are inherently better for the environment.

It seems to me that there is an ideal size for a city, and that beyond that point, it becomes unmanageable. I believe that Christopher Alexander (author of “A Pattern Language”) suggested a size of around 10,000. Margolin and Buchanan (authors of “The Idea of Design”) made a higher estimate of around 50,000 – still considered a “small town” by some people.

I’d be interested in hearing the author’s thoughts on this. As mentioned here, for all but the past two decades, most people lived a rural existence. People were drawn to the city by industrialization and the promise of jobs, but the industrialized and centralized city has become something that many people wish to escape from.

Posted by Nullcorp | Report as abusive

The modern city isn’t a consistent object: many cities these days are seeing employment – particularly privately-owned operations – migrating from the core to the outskirts, while households are flocking to developments within the core zone. The drivers are usually issues like congestion, pollution and taxation. However, this shift in activity is messing up some of the base assumptions that led to the existing configuration of services. Commute directions need to accomodate increased reverse flow; food, water and energy distributions are altered.
Preparations for the unexpected, if they fail to take these ongoing changes into account, can become ineffective or counterproductive. Will the demographic shifts continue? A lot depends on the administrative policies that have influenced the current patterns. Will the new emphasis on reducing debt and public spending have an effect? That’s really quite difficult to say with any certainty. Stay tuned!

Posted by AltonBob | Report as abusive