The world’s biggest cities are growing at an unprecedented rate, with 11 of the planet’s 30 biggest cities each adding more than ten million citizens over the last four decades, according to a new study by researchers at the Universities of Birmingham and Sheffield in England.
In 2014, the 30 ‘megacities’ – defined as cities with a population of more than ten million – analysed contained a total of more than 558 million people or 8.2% of the world’s population. In 1975, however, they contained less than half this total at 261 million or 6.4% of the then global population.
Rapid and large-scale urban growth can cause major problems in areas such as housing, infrastructure, basic services, food security, health and education.
The study reports that there has been remarkable population growth in urban areas in Asia over the past 40 years, with slower growth found in traditional, long-established urban centres in Europe and the US.
Guangzhou and Shenzhen in China added over ten million people from 1975 to 1990 and again from 2000 to 2014, while Jakarta in Indonesia added over ten million people between 2000 and 2014.
Dhaka in Bangladesh, Manila in the Philippines and China’s Shanghai all more than trebled in size between 1975 and 1990, with Bangalore in India and Beijing quadrupling their populations.
Report author Charlotte Hoole from the University of Birmingham, said, “There are some particularly striking findings that demonstrate a rate of urbanisation which is often seen as neither sustainable nor desirable, yet it is the lived reality for residents and policy makers in many large cities across the global South.
“Whilst high population density in itself is not necessarily problematic – the affluent urban centres of Seoul, Hong Kong and Tokyo are good examples of high-density megacity living – it requires infrastructure, long-term planning and significant capital investment.”