1. Megacities: The Asian Era

Asian megacities concentrate 60 % of world megacities population in 2010. The demographic trend which lead to this current situation since the 1960 is exposed. Then the population mass of these megacities is compared to their economic weight opening on a reflexion on their position within the world cities system. The analyse is supported by an original geodatabase in which all the 2010’ 100 largest cities in the world are defined as physical agglomerations, using remote sensing images and census data series in order to assess their population size.

Using methods developed for detecting the trends in complex systems, we classify world megacities regarding their demographic trajectories, then Asian megacities individual trajectories are related to the evolution of all other cities of their respective countries. Demographic trajectories of world cities appear partly related to their location and dominated by the shift from the Atlantic to the Asian shores. However, the Asian megacities trajectories remain very diverse. Their weight in their respective urban system do not grow up. Moreover, Asian megacities become bigger by expanding functionally in metropolitan region marked by polycentrism and tend to form huge Mega Urban Region that shares an important part of Asian population and national economy. The analyses of a harmonized database of city’s GDP highlight the wealth concentration by Asia’s megacities. It significantly vary according to the country size, and are much more important at a regional scale, where these Mega Urban Regions emerge. As GDP, the income polarisation among Asian Megacities is not acute. A transitional disequilibrium in population growth and inequities remain, but it don’t constitute a factor of economic stagnation.