Wednesday, April 13, 2011

The Impact of Cities on the Environment

The environmental impact of cities (22 page pdf, Peter Newman, Environment and Urbanization, Oct. 2006)

Today’s review is of a paper by Prof Newman, recently the environment commissioner for Sydney, Australia. The paper compares three methods of estimating urban impacts: population impact method, ecological footprint and sustainability assessment, concluding that the latter offers the most in terms of positive policy objectives.



Key Quotes:

“Although the population impact model provides some perspective on local impact, and the Ecological Footprint model on global impact, only the sustainability assessment approach allows us to see the positive benefits of urban growth and provides policy options that can help cities reduce their local and global impact while improving their liveability and opportunity, which continue to drive their growth”

Population Impact Approach

“there are many aspects of cities that are not explained by this simple biological model. It does not explain why people are attracted to cities, or how economies of scale and density can actually lead to better urban services that manage natural resources and wastes or public transport”

“The top four “alpha” cities of the global economy – London, Paris, Tokyo and New York – still appeal to their residents and visitors despite being large and dense”

“The idea of spreading the population of such cities into small systems of intensive rural production has been suggested by some, although the arithmetic shows that a complete destruction of the most productive agricultural land would soon occur”

Ecological Footprint

“The calculation is largely artificial in that it relates energy consumption to the amount of land that would be needed to grow the equivalent in fuel crops”

“It is still mostly a negative measure of the impact of cities rather than a more positive measure of what cities should do”

Sustainability Assessment

“The objective of sustainability assessment is to achieve a simultaneous consideration of social, economic and environmental issues and to achieve a “net benefit” outcome in each area, with minimal trade-offs”

“defined sustainability as . . reducing Ecological Footprint (energy, water, land materials, waste) while simultaneously improving quality of life (health, housing, employment, community . . .) within the capacity constraints of the city.”

“Sustainability assessment approaches the future by asking of any development that it produce “net benefit” in all three areas of environment, social and economic performance. This means that there should not be a trade-off between the three areas, as has so often been the case”
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