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Urban planning
ChinaScience

World’s cities doubled in land use over 20 years, with America leading urban sprawl, study finds

  • The rural-urban divide is a cause of global inequality, but both excessive density and the drive for lower density can be detrimental
  • Cities in Europe, Africa and South America were hemmed in by limits on either space or finances

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Researchers estimate that the collective space taken up by cities has more than doubled in 20 years – from 240,000 sq km in 2000 to 520,000 sq km in 2020. Photo: Reuters/Nasa
Stephen Chen

The collective size of cities more than doubled over the past two decades in an unequal pace of expansion across the globe, according to a new study by Chinese researchers.

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Measurements based on satellite images suggest the total size of urban areas increased from nearly 240,000 sq km (92,700 square miles) in the year 2000 to almost 520,000 sq km (200,000 square miles) in 2020.

North American cities had the fastest rate of expansion at 3,921 sq km per year.

Chinese cities trailed closely behind with a 73,300 sq km increase in total.

“The urban expansion in South America (16,600 sq km total), Africa (22,500), and Oceania (3,200) represented low amounts in the past 20 years,” said the research team in a paper published in Science Bulletin on Tuesday.

The team was led by Dr Kuang Wenhui of the Institute of the Geographic Sciences and Natural Resources Research at the Chinese Academy of Sciences in Beijing

Despite their problems, cities have many advantages over rural areas. Urban dwellers tend to have higher salaries and easier access to education, entertainment and health care. The rural-urban divide is a significant cause of global inequality, according to the United Nations.
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