22 de dezembro de 2013

Megacities of tomorrow

Half of humankind now lives in cities and, to nearly one in ten city-dwellers, a megacity is home. thirty years ago, there were just three cities with a population of 10 million or more, the definition of a megacity: Mexico city, new York city and tokyo. today, a further 17 cities have joined their ranks and others hover just below the threshold.

Megacities as far apart as Jakarta, Lagos, Manila, Mumbai, Bangkok, New York, Osaka-Kobe, Rio de Janeiro, São Paulo and Shanghai all have at least one thing in common: they are concentrated on narrow coastal strips. other megacities are finding their plans for expansion constrained by natural obstacles like mountain ranges, volcanoes or earthquake fault lines, or by the development of necessary peri-urban agriculture and green belts.

Megacities are running out of space and the price of land is sky-high. They will have no choice in future but to make a more rational use of the space available to them. More and more, architects will wish to build not only high but also deep. This is more expensive in the short term but much more sustainable in the long term. Designing the megacity of the future – one of ten themes within the International Year of Planet earth – will take a lot of planning and foresight. The expertise of geoscientists and geographers will be indispensable in ensuring that life in tomorrow’s megacities is comfortable, sustainable and safe.

The United Nations predicts in its medium scenario that 9.2 billion people will live on our planet by 2050. From then onwards, the population is expected to remain more or less constant until at least 2300. Virtually all population growth between 2010 and 2030 will be concentrated in cities. Even now, mega-urbanization is generating more competition for space, particularly in the sought-after central city where skyscrapers sprout. Extending outwards is not always easy, as urban sprawl is often restricted by physical bound- aries like the sea or mountains. Cities can tunnel through mountains, of course, but this necessitates good engineering.

Ler artigo completo:

A World of SCIENCE, Vol. 6, no. 4, October–December 2008

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