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Megacity Metabolism

Not all population centers process energy the same way.

By Gemma TarlachMarch 31, 2016 5:00 AM
Megacities show up clearly at night. | NASA Earth Observatory/NOAA NGDC


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The future of our species, many researchers believe, lies in sustainable megacities that can support dense populations through efficient resource management. We’ve got a long way to go.

A study in the Proceedings of the National Academy of Sciences provided the first-ever comprehensive comparison of Earth’s 27 megacities, defined as metropolitan areas with populations of 10 million or more. The survey identified some big disparities: New York, for example, gobbles up significantly more energy than Tokyo, even though the Big Apple has 12 million fewer people.

Gathering the data was the first step in a multiphase project to identify strategies that will help all cities effectively sip, rather than chug, available resources, says the study’s lead author Chris Kennedy, an industrial ecologist at the University of Victoria in British Columbia. It’s an important goal: By 2020, we’ll likely see another 10 megacities on the planet.

Kennedy remains positive: “I’m more optimistic about creating sustainable megacities now than I was before we started the research. Although the challenge is bigger than most people realize — it’s daunting, really — now it’s better understood.”

Earth's 27 Megacities:

  • Contain 6.7 percent of the world's population, or 460 million people.

  • Generate 14.6 percent of the world's total GDP

  • Use 9.3 percent of global electricity

  • Produce 12.6 percent of the world's solid waste.


These eight cities account for much of the world’s energy consumption and waste. Population size is based on an earlier study (Brinkoff, 2010) cited by authors. Annual per capita consumption of both heating and industrial fuels and transportation fuels is shown in GJ (gigajoules, where 1 GJ is about two-thirds the energy of a typical lightning bolt). Annual per capita electricity consumption is shown in MWh (megawatt-hours). Annual per capita waste produced is shown in t (tonne or metric ton, the equivalent of 2,205 pounds). All data through 2011.

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