I live, fairly happily, in the world's most wasteful megacity. It is a densely populated, steadily aging, consumerist utopia where we buy, and throw away, a staggering amount of stuff. Where some faucet, toilet, or pipe, is constantly leaking in our apartments. Where an armada of commerce-beckoning lights are always on. Where a fleet of gas-guzzling cars still clog the roadways. I, along with my twenty million or so neighbors, help New York City use more energy, suck down more water, and spew out more solid waste than any other mega-metropolitan area.
The new PNAS research goes to some lengths to document the "megacity metabolism"—or how, exactly, energy and resources flow through these megacities. It is, as the authors note, "a major undertaking, not previously achieved." But it turns out that these massive hubs of humanity are actually, at the moment, using more energy than their non-mega civilizational counterparts.
That's important because prominent urbanists and modernist environmentalists are betting that city life will drive down waste and energy use. It doubtlessly harbors the potential to do exactly that: When people live closer together, there's less energy wasted transporting humans and goods. Public transit can replace automobiles. There's more reliance on commons and public spaces. It's a cleaner, more efficient system.
The efficiencies and advantages of close quarters living are in constant tension with our impulse to consume, which New York makes really easy to do
But just producing a dense city doesn't guarantee greenness, as Kennedy's work emphasizes.
"[A]s cities get larger, social characteristics such as GDP, innovation and crime increase in per capita terms, while infrastructure system requirements (miles of pipes or wires) decrease in per capita terms," Kennedy told me in an email. "With respect to the sustainability or environmental impacts of cities we might thus argue that there is a trade-off between the wealth effects and the infrastructure efficiency effects."
The efficiencies and advantages of close quarters living are in constant tension with our impulse to consume, which New York makes really easy to do. Kennedy's research finds that when megacities get rich, a la New York, they also get wasteful. "A possible interpretation of our results for the megacities is that the wealth effects are dominating with respect to solid waste production, electricity use and gasoline use (all at higher than global average rates)," he said, "but with respect to total direct energy consumption the two effects are about equal." Cities foster innovation and create wealth, yes, but that, in places like New York, leads to more consumption.
We may hear about New York's myriad and noble sustainability initiatives, or how the future of green living is to be found in the city—but also bear in mind those leaky pipes, the cabs cramming the Brooklyn Bridge, the supercharged skyscrapers, and the bag after bag of trash you haul downstairs from your third floor walkup.
Kennedy says that "yes, our megacity results are counter to the idea that cities are currently using energy more efficiently, although perhaps this might still change in the future." That's key—the research also points out that some megacities boast very sustainable features.
Tokyo's good urban design and top notch public transportation system make it an exemplar in urban power use. It also does a bang-up job of fixing its leaky pipes. Moscow, which Kennedy tells me is otherwise the only true competitor for New York's per capita wastefulness—it's the only city that used up more power—has a great heat distribution system; it uses waste heat from its power plants to heat its homes. And in London, "where the share of municipal solid waste landfilled in the United Kingdom has fallen from 80% in 2001 to 49% in 2010," according to the paper, a landfill tax has greatly reduced its trash output.
And none of this is to say that big cities don't still hold the promise of a more efficient, less wasteful future. "Our findings support the established understanding that compact cities are the way to go," Kennedy told me.
We just need to get better at designing, operating, and regulating them. Megacities are the future, whether we like it or not, and they present an opportunity to configure society to effectively brace for a warmer, stormier, and resource-scarce world. We just need their energy and waste flows to look more like Tokyo, and less like New York.