By 2050, the global population is expected to soar to 9.7 billion, with 68% of the population living in urban areas. (Note 1) In the first-ever study on the characteristics of urbanization in large cities around the world, researchers at the Department of Civil Engineering of the University of Hong Kong (HKU) analyzed cities’ urban built-up areas (BUAs) expansion, population growth and greening BUA changes, and revealed a hugely uneven pace of urbanization in those cities in the last two decades.