Yunyu Tian (Wageningen University) A global analysis of multifaceted urbanization and its effect on Sustainable Development Goals using Earth Observation

Urbanization is accelerating across the world, resulting in built-up expansion and more urban residents. Exploring multi-characteristics of urbanization and its impact on environment is essential towards achieving global sustainable development. Here we aimed to characterize urbanization from 1975 to 2015 in terms of population density and built-up structure per 5 × 5 km2 grid covering global inhabited areas, and then to explore the effect of urbanization on SDG trends in land use efficiency, energy intensity and air quality (PM2.5). We used global high-resolution data of multi-temporal built-up area and population (Global Human Settlement Layer), and Nighttime light for energy consumption. 1) In addition to the steady expansion of built-up areas, our results emphasize the multifaceted nature of urbanization that varies greatly across regions and times. Increased population density and built-up patch density were the dominant characteristics in Asia and Africa. Decreasing population occurs in a significant portion of Europe and selected regions in North America. During different historical periods (1975-1990, 1990-2000, and 2000-2015), rates of increase in population and built-up density were slowing in urban, suburban and rural areas. 2) Effects of urbanization on SDG trends were complex and varied by continent. For example, we found positive relation between urbanization and energy intensity but negative relation between urbanization and air pollution in Europe, North America and Australia.