RESUMO
Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world's 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001-2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth.
RESUMO
This article consists of two parts. The first shows how the principles of the ecosystem approach can be applied to green rooftops, and the second attempts to illustrate it through a case study. In particular, it suggests new approaches and techniques for creation of green rooftops in a perspective of urban habitat network and urban biosphere reserve. To endow urban rooftops with the roles and functions of urban habitat network and urban biosphere reserve, it is necessary to apply "an ecosystem approach to urban management." In this article, an ecosystem approach to urban management is illustrated with Seoul as an example. The Habitat Network in Seoul will be reviewed with a focus on the model suggested by MAB Urban Group. Then, the roles and functions of Myeongdong UNESCO Green Rooftop and its possible contribution to building the Seoul Urban Biosphere Network will be described. The UNESCO Green Rooftop is 628 m(2) and was created on the 12th floor rooftop of UNESCO Building in Myeongdong 2-ga, Jung-ku, Seoul. In the green rooftop, which was created with goals of securing green areas and biotopes in downtown, creating an urban econetwork, securing a base for urban ecosystem study and environment education, and disseminating an idea of coexistence between nature and humankind, wetland, meadow, scrub and woodland, wall revegetation, and a vegetable field are created. Also, rainwater recycling facilities and a solar energy water circulation system were set up. Rest facilities including observation and education facilities were built. Based on the Seoul example, as well as urban biosphere reserve models suggested by the MAB Urban Group, we suggest several principles to be applied for a green rooftops to qualify as a category of urban biosphere reserves.