Developing cities have strategies that condemn them to a relatively high carbon future

Tim Chapman reflects on how the challenges of urbanisation will be met in the next four decades

Urbanisation is an unprecedented challenge. By 2050, it is predicted that the world’s population will reach more than nine billion, with 75% of the Earth’s inhabitants living in cities. The first cities emerged around 4,500 years ago, but all that remains of these ancient settlements are piles of stones being picked over by archaeologists. Many of our modern great cities were founded comparatively recently, so how will the cities of tomorrow thrive?

Cities are valued for the quality of life and opportunities they offer, not just for the economic benefits. Services can be provided more efficiently – and, increasingly, in a lower carbon way. So what makes a city that people want to live in?

Professor Brian Collins, of University College London, recently summarised the five key characteristics necessary for a city to thrive: it must be courteous; it must be active and inclusive; there must be much public space; it should be healthy; and it must be evolving. Behind these, there needs to be supporting soft and hard infrastructure to connect places, services and – critically – people. We, as engineers, must facilitate that great system of systems to accomplish all of these things.

These infrastructure structures must be resilient, with very low levels of outage, because so many people depend on them to function effectively. A total failure of infrastructure can create severe problems for urban dwellers within 24 hours; people will have no water to drink or to wash away waste, and food in warm fridges will start to decay. In addition, the hugely complex logistics chains will quickly grind to a halt when transport is curtailed.

A recent UK example of a total infrastructure failure occurred in Lancaster in December 2015.1 Fluvial flooding submerged a key transformer just outside the city, leaving 61,000 homes and surrounding businesses without power – and all supporting infrastructure failed. It was six days before the city returned to normal, thanks to huge pumps airlifted into position by the RAF and massive standby diesel generators. In the meantime, the population faced a very worrying time, deprived of all the usual information sources – TV, radio, the internet – that would have provided reassurance. Many cities in the developing world face far worse, such as earthquakes, mudflows, sinkholes and extreme flooding hazards, and need to be made to withstand these comfortably.

An even bigger challenge for humanity is how to cope with resource scarcity and the effects of our profligate carbon pollution. This threatens to change our climate significantly, and only the rich world will be able to adapt adequately. Engineers have addressed similar pestilences before – think ‘the great stink’ of the 19th century and the ‘pea-soupers’ of the 20th, when better infrastructure and regulation led to respite. We are leading the way in devising efficient solutions to these carbon problems, so the key question is whether they will be implemented in time.

In the developing world, many cities are growing out of control, with rudimentary infrastructure that cannot keep pace with ballooning population growth. In the developed world – where, generally, we are coping with established cities growing relatively slowly – there is an obligation to help. Initiatives such as the C40 network of global megacities2 and the Rockefeller 100 Resilient Cities3 show how knowledge can be shared productively for the good of all of humanity.

The choice of power sources is key, since many developing cities have energy strategies that condemn them to a relatively high carbon future. The dominant transport mode is also important; it needs to connect people’s homes to jobs, education, health, culture and their social lives. Other ‘hard’ networks – water, waste, data and urban protection – complete the big infrastructure tableau.

Urban masterplanning is reaching maturity, with the key ingredients for urban vitality much better understood. However, creators of infrastructure systems are only sometimes seizing the chance to produce cities that are successful, resilient and low carbon. Engineers need to contribute far more to the overall approach. We have a vital role to play in how cities develop over the next 35 years, but we need to be more assertive with planners, politicians and the media in advancing the urbanism agenda. We need to make sure that society recognises the huge role that those systems have in turning our great cities into even better places to live.


  1. Living without electricity, Royal Academy of Engineering, May 2016.
  2. C40 Cities Global Leadership on Climate Change 
  3. 100 Resilient Cities 

Tim Chapman is director and leader of Arup’s Infrastructure London Group