How much of the world’s land has been urbanized, really? A hierarchical framework for avoiding confusion

摘要: Urbanization has transformed the world’s landscapes, resulting in a series of ecological and environmental problems. To assess urbanization impacts improve sustainability, one first questions that we must address is: how much land been urbanized? Unfortunately, estimates global urban reported literature vary widely from less than 1–3 % primarily because different definitions were used. evade confusion, here propose hierarchical framework for representing communicating spatial extent urbanized at global, regional, more local levels. The consists three spatially nested definitions: “urban area” is delineated by administrative boundaries, “built-up dominated artificial surfaces, “impervious surface devoid life. These are really measures urbanization. In 2010, was close to 3 %, built-up area about 0.65 %, impervious merely 0.45 %, word’s total (excluding Antarctica Greenland). We argue this hierarchy measures, particular ratios between them, can also facilitate better understanding biophysical socioeconomic processes