Tuesday, October 14, 2008

The greenhouse impact of cities

A recent paper by Satterthwaite argues that the contribution of greenhouse gases from cities has been greatly over-stated. In the past, some have claimed that 75% to 80% of all greenhouse gases come from cities. The author believes the number is closer to less than 50%, if you do the accounting right. He then gives a detailed discussion of what it means to even blame cities.

Buried within this paper (which is generally critical of footprint calculations), now out in Ecological Economics, I argue that cities are not the problem, but in fact are a solution. If everyone lived in suburbs or rural areas, our greenhouse gas output would be much higher as we’d need so much more transportation. Cities are a very efficient way for people to gather.

The bigger point I make in that paper though is that such forms of accounting, even if done right, as Satterthwaite seems to have done, are meaningless. Cities are arbitrary boundaries, especially for greenhouse gas accounting, and so this means nothing. All we’re really finding is that cities are dense, and the rich consume more than the poor. I hope no one is surprised by either of those findings.

In fact, carbon footprints are really a measure of inequality more than anything else. Most of any carbon footprint from a given area comes from the rich, whether we measure by country, state, city or block.

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