These images from NASA show the extraordinary pace and extent of growth of urbanisation in China’s Pearl River Delta (Zhu San Jiao) over the past few decades.
The top image shows the mostly rural scene in 1988 when an interlacing network of rivers and streams flowed through fertile alluvial soils full of rice paddies, wheat fields, mulberry orchards, and fish ponds.
The population of the region in 1988 was around 10 million scattered between several medium-sized cities, including Shenzhen, Guangzhou, Foshan, and Dongguan.
Nearly three decades later, these cities have grown so rapidly that they have merged into an interconnected megalopolis with a population of 42 million – greater than that of Australia, Argentina, or Canada.
If taken as one conurbation, the Pearl River Delta region has overtaken Tokyo as the world’s largest urban area.
Bill Condie is a science journalist based in Adelaide, Australia.
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