Let’s Start with the Megacity Metabolism

Let’s Start with the Megacity Metabolism

By Kristen Johnsen


| Megacities, like New York for example, are defined as metropolitan areas with populations greater than 10 million. Megacities are a growing phenomenon. In 1970 there were only eight of them in the world. Today there are twenty-seven. This staggering increase is the result of both exponential global population growth, and the growing trend of urbanization. It is estimated that by 2020 there will be thirty-seven such cities.

Engineers at the University of Toronto recently set out to determine the environmental impacts of this urbanization trend; their results were disconcerting. The data indicates that while megacities host only 6.7 percent of the global population today, they exhaust 9.3 percent of global electricity and produce 12.6 per cent of global waste. Overall, megacities have a very high resource metabolism; they go through them quick and discard the waste.

The unsustainable nature of megacities has huge implications for global sustainability trends. Over time, humans will not only consume more resources overall because of population growth, they will consume more per capita because of the growing popularity of Megacities. Experts like Chris Kennedy, a researcher with U of T, suggests that there may be a way to fix this. Since megacities contain such a high number of people, if we were to target megacities structurally and improve their sustainability, it would be the most efficient way to improve the consumer practices of the most people in the least time. Making megacities more sustainable is a great way to start making real progress.

But how do we change the consumption of an entire city? Chris Kennedy answered that question with another data set. The research group stored data from all megacities worldwide and determined the metabolism of each one. That means they determined how natural resources pass through each one. Essentially, the research group was able to see which city polices are effective in improving city-wide sustainability, and which are not. The theory is that the effective and sustainable policies can be applied elsewhere.

Kennedy asserts that variables that might make a place more or less sustainable like climate, culture, and wealth can be managed. Policies can still be adapted. Careful comparisons can be made. The comparison of Tokyo and New York, for example, is particularly useful. It demonstrates the substantial role that city policy plays in resource use. While “The New York metropolis has 12 million fewer people than Tokyo, it uses more energy in total: the equivalent of one oil supertanker every 1.5 days.” Imagine if New York could just be as sustainable as Tokyo. That would be a great start.

The Tokyo model is useful for addressing the mentality of responsible sustainability. Standing in start comparison to some cities, Tokyo been very proactive in conserving resources it is short on or will be short on in the future. The resultant urban policies reduce Tokyo resource use, even with a growing GDP and population. One example is water: by aggressively addressing leaky pipes, Tokyo has reduced water losses to 3%. This is much different than “places that are really short of water, and yet they’re leaking it away,” said Kennedy. The mentality is responsible; address the issue.

In the study, Kennedy and his team shared several other successful policies:

  • Moscow has built the largest district heating system in the world, providing combined heat and power to buildings housing 12 million people; this being more efficient that using separate systems for each building.
  • Seoul has developed a system for reclaiming used wastewater for secondary uses like flushing toilets, increasing the overall efficiency of water use.
  • London has been subject to rising electricity costs and taxes on the disposal of solid waste. It is the only megacity for which per capita electricity use is going down even as GDP goes up.

Smart policy makes a difference. “What we’re talking about are not short-term, one-election issues, but long-term policies on infrastructure that shape cities over years or decades,” said Kennedy.

“The evidence is that megacities can make some progress in reducing overall resource use, and I think that’s encouraging.”

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