Megacities and the Global Environment

  1. C-08
  2. CR①
  3. CR②


Project Leader


The University of Tokyo

>> Annual Report
Figure City sustainability index (CSI)

Figure City sustainability index (CSI)
A model constructed to invesigate the sustainability of 18 megacities (Tokyo, Jakarta, Seoul, Mumbai, Sao Paulo, Mexico City, Manila, New Delhi, Cairo, Kolkata, Osaka-Kobe, Shanghai, Buenos Aires, New York, Los Angeles, Karachi, Dhaka, and Moscow).

What, and how much, have we learned?

The seven findings presented below represent the accomplishments of the Megacity Project over the past five years.

(1) We identified the principle underlying the ideal organization of megacities from the standpoint of sustainability of human society. That is to say, we delineated constraints for cities so that the burden they place on the global environment does not exceed planetary boundaries. In order to enable this, it is necessary to mobilize humanity in a direction that maximizes the economic and social potential of cities. In doing so, it is critically important that we simultaneously pursue optimal benefits in the three areas of global environment, society, and economy (the triple benefit principle)

(2) We developed the City Sustainability Index (CSI) as a means of assessing megacities. Using this index, we assessed 18 megacities and found that none can be considered sustainable at present (Figure). What policies and measures, then, are needed to respond to this situation? In reply to this question we proposed a fundamental approach to achieving the ideal organization of megacities (3), which we coined “radical incrementalism with long-term vision.” Megacities are extremely large and complex. At present, it is not possible to find an optimal solution for all aspects of megacities. Radical incrementalism entails (a) repeatedly choosing actions from among the feasible options that are locally optimal in the short-term while (b) maintaining a long-term vision for pursuing sustainability for humankind and (c) emphasizing a city’s history.

Similarly, in order to deal with the size and complexity of megacities, it is necessary to deliberate on the ideal organization of cities with a wide range of experts and variety of stakeholders. We proposed a “megacity scenario-based approach” (4) as a means for realizing such co-design. Furthermore, as a prerequisite to achieving the ideal organization of megacities, we pointed out the importance of taking the local ecosphere into consideration while also paying attention to the geographic characteristics and history of a given city (5). Each megacity is influenced by the climate, livelihood patterns, and topography of the particular ecosphere in which it is located, whether it be in the Monsoon Asia or mid-latitude arid region. Each megacity is further constrained, in both positive sense and negative senses, by events that occur on the time axis.

We also pointed out that in order to realize the ideal organization of megacities, we should focus on “residential environment” (6), which is the most important space in which humans live. The Megacity Project identified two means of intervening in the residential environment based on an inclusive urbanism approach focusing on the triple benefit society. Furthermore, we pointed out that in order to achieve the ideal organization of megacities, we should pay close attention to the economic development of the middle class (7). This focus on the economic component of the triplet benefit stems from the belief that people begin to consider the sustainability of human society only after they feel a certain degree of economic affluence.

Our vision of global environmental studies

Global environmental studies integrates a wide range of disciplines in order to think about the means necessary “for humankind to continue existing on the planet called Earth while enjoying a certain degree of affluence.” There are a number of possible approaches to creating such a field of study. In our project, we focused on cities, which are home to half of the world’s population, and, especially among these, on 18 megacities with a population of 10 million or greater.

New connections

The identification and development of the seven concepts and approaches presented above represent the accomplishments of our Megacity Project. Detailed content of each can be found in Shiriizu: Megashitii (Series: Megacities) a complete set of 6 volumes scheduled to be published by the University of Tokyo Press in 2016.