Sunday, August 28, 2011

Urban Superlinear Scaling

The current issue of Scientific American covers the new science of why cities become more productive and efficient as they grow (Bigger Cities Do More with Less by Luis Bettencourt and Geoffrey West).  The new science is multidisciplinary and is beginning to reveal key answers to urban growth - - cities concentrate, accelerate, and diversify social and economic activity.

Key points in the article include:
  • Compared with suburban or rural areas, cities do more with less.  Often large cities are the greenest places on the planet because people living in denser habitats typically have smaller energy footprints, requires less infrastructure and consume less of the world's resources per capita.
  • This new science is being made possible by the increasing availability of public and private information.
  • If eight million people all live in one city, their economic output will typically be about 15 percent greater than if the same eight million people lived in two cities of half the size.
  • Superlinear scaling - - this is the fact that the socioeconomic properties of cities increases faster than a direct (or linear) relation to their population would predict.
  • When the size of a city doubles, its material infrastructure structure (from the number of gas stations to the total length of its pipes, roads, or electrical wires) does not.  Instead these quantities rise more slowly than population size.
  • On average, the bigger the city, the more efficient its use of infrastructure, leading to important savings in materials, energy and emissions.
  • Superlinear scaling is seen all over the globe - - US cities and cities in China and Brazil.  The same basic social and economic processes are at work.
  • Increased population promotes more intense and frequent social interactions, occurrences that correlate with higher rates of productivity and innovation, as well as economic pressures that weed our inefficiencies.
  • Cities with high rents push urbanites to come up with new forms of organizations, products and services that carry more value added.
  • The largest US cities have the lowest carbon dioxide emissions per capita.  This gain is mostly an unplanned by product of people living at greater densities because the bulk of the savings comes from energy-efficient public transportation and simple walking instead of driving, which is almost 10 times more energy-intensive.
  • This can be more challenging for developing countries such as China and India - - much of their infrastructure improvements has yet to be built.
  • Cities are never in a state of equilibrium - - a kind of tug-of-war between the forces of growth and innovation and the forces that want to tear them apart.

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