The Incredible Voraciousness of Cities

As part of this month's special report on megacities, we asked Senior Associate Editor Samuel K. Moore to do a little research on the fundamentals of supporting a major metropolis. He found that there is not a lot of hard data available on what makes big cities tick. But he did find some surprising results from a study of one world capital--London--that indicate we should be paying more attention to the overall requirements of these enormous communities. In his report, "How to Measure a City's Metabolism", Moore describes a situation in which the world's cities are literally consuming the resources of the rest of the planet.

The United Nations provides a standard set of data for each country regarding the import, production, and export of key goods such as corn, petroleum, and metals. However, it does not treat cities separately. Instead, an independent group of researchers, called the Global Footprint Network (GFN), based in Oakland, Calif., provides an alternate analysis to describe how much land is commandeered to support cities. This ecological-footprint analysis examines the flow of materials and energy into and out of an area and then determines how much productive land and water is needed to supply the renewable resources involved and to deal with the waste generated.

As Moore informs us, these scientists have established a unit of measure, known as the global hectare, for calculating the surface space required to process the needs of an average community. According to a study called the Living Planet Report 2006 by the GFN and its partners, each person on Earth consumed the renewable resources of 2.2 such global hectares in 2003. Unfortunately, there are only 1.8 global hectares per person available.

So far, the largest urban area to have its ecology measured systematically is London. British researchers found that London's ecological footprint was 49 million global hectares--293 times its geographical area and equivalent to two United Kingdoms. On a per-person basis, Londoners took up 6.6 global hectares, putting them on a par with the Swiss and making them twice as frugal as the average American, but still more than three times as voracious as what the Earth can provide.

It's a sobering statistic. London alone is consuming twice the space on the planet that its entire nation is capable of supporting. For now, that sleight of hand between what the developed world is devouring and what the undeveloped world has left is the geopolitical equivalent of the old pea-in-the-shell game. It's a sure thing--for the one taking the bets. Sooner or later, though, the "suckers" are going to get upset that they've been had. When that happens, all bets are going to be off. And the great cities of the world are going to be left holding the bag.

We've been warned. The real wonder is whether we'll ever do enough to prevent the worst from happening.


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