In 2015 the world’s urban population was almost 4 billion people. The United Nations predicts this figure will grow by an additional 2.3 billion over the next three decades with a total of 6.3 billion people (equivalent to 66 percent of the world’s population) living in cities by 2050.

While urbanisation presents a number of opportunities including the promise of better services, stronger economies and connections, it also poses a number of complex challenges.

"Over the last couple of decades, the whole world has experienced accelerated urbanisation which has seen billions of people moving into cities," says urban environment expert Professor Xuemei Bai of the Fenner School of Environment & Society at ANU.

"Much of this growth is happening in the developing world, particularly in Africa and Asia where cities don’t have the financial capacity or knowledge-base to deal with the rapid rate of population growth," she says. 

In developing countries, a significant number of new urban residents are forced to live in poor housing conditions that lack basic amenities such as clean water and sanitation.

"If we want to turn these global urbanisation challenges into opportunities, we must urgently re-think how we live and work together," says Professor Bai.

There is no one-size-fits-all approach.

"Cities around the world experiencing different urbanisation trends," says Professor Bai.

Solutions must address local issues, as well as taking into account emerging global patterns.

"Global urbanisation is a complex picture when you look at different regions and socio-economic contexts.

"This presents a number of challenges, particularly for developing countries," she says.

New, integrated knowledge is required.

The growing complexity of global urbanisation necessitates the use of more sophisticated measurement tools and indicators to inform urban policy and planning decisions.

"Traditionally, urban strategy has been considered the domain of urban planners, but this has to change.

"Scientific input is needed if we want to change the trajectory of urbanisation to a more sustainable path," says Professor Bai.

Collaboration is key.

A more inclusive, collaborative approach by governments and intergovernmental agencies is essential.  

"Solving these challenges cannot be done behind closed doors by academics alone. A new integrated urban knowledge is needed.

"Governments, academics, practitioners, industry and the general public must all work together to tackle these complex issues," says Professor Bai.

This is the rationale for Urban Planet: Knowledge towards Sustainable Cities, a new book co-edited and co-authored by Professor Bai. It brings together over 100 experts from the fields of science, architecture, journalism, art, design and social sciences to develop creative solutions to address the unprecedented challenges of rapid global urbanisation.

"There are sometimes drastically different perspectives between practitioners and academics. We need to pursue more universal and scalable patterns and processes that can be used in both the global north and global south," says the editor of Urban Planet, Professor Thomas Elmqvist of the Stockholm Resilience Centre at Stockholm University.

The time to act is now.

Urbanisation is a global issue. Concerted action is urgently required across geographic, disciplinary and sectoral boundaries from local to global and across private, government, research and industry. 

‘The window of opportunity to influence urbanisation and make it more sustainable is closing, we have to act urgently,’ says Professor Bai.

Professor Xuemei Bai is a Professor of Urban Environment and Human Ecology in the Fenner School of Enviornment and Society at ANU. She is co-editor, lead author of the synthesis chapter,  and co-author of several other chapters of ‘Urban Planet: Knowledge towards Sustainable Cities’. 

Urban Planet was produced as the result of a collaborative Future Earth project. It is available in hard cover and open access online via Cambridge University Press.

Written by Kate Hulm, Senior Communications Project Officer, Fenner School of Environment & Society.