Researchers at Princeton University at East China Normal University used satellite imagery to map urban growth between 1985 and 2015. Research shows that over the past 30 years, the global urban area has expanded by 80%, and the growth rate of the urban population is much higher than the global population growth rate.
The paper was published in the journal Nature-Sustainability. The researchers found that from 1985 to 2015, the global urban area increased from 3627,000 square kilometers to 6534,000 square kilometers, with a net expansion rate of 80%, with an average of 9687 square kilometers of land shifting from non-urban to urban land.
This is four times higher than previous estimates. About 69 per cent of these new development urban areas are located in Asia and North America, and the urban areas of these two continents have increased by 4,970 to 319 square kilometres and 2,358 to 150 square kilometres per year, respectively.
In terms of countries, the United States, China and India have the largest number of cities and have experienced different urbanization trajectories. Urban expansion in China and India has occurred mainly in large cities and in and around rural areas. Among them, China’s urban growth is mainly concentrated in the Beijing-Tianjin-Hebei region, the Yangtze River Delta, the Pearl River Delta. Growth in these specific urban areas accounts for more than 60% of China’s total urban expansion.