Feeding the World in 21st Century: ‘Cities Like Forests’

A leading proponent of vertical farming discusses how urban areas (DesPardes Editor’s note: like Karachi, Lahore, Dhaka, Mumbai, etc.) should adapt to a perilous environmental future.

Jon Michaud at The New Yorker: In 2000, Dickson D. Despommier, then a professor of public health and microbiology at Columbia University, was teaching a class on medical ecology in which he asked his students, “What will the world be like in 2050?,” and a follow-up, “What would you like the world to be like in 2050?” As Despommier told The New Yorker’s Ian Frazier in 2017, his students “decided that by 2050 the planet will be really crowded, with eight or nine billion people, and they wanted New York City to be able to feed its population entirely on crops grown within its own geographic limit.” The class had calculated that by farming every square foot of rooftop space in the city, you could provide enough calories to feed only about two per cent of the 2050 population of New York.

Urban farming was a good idea, Despommier thought, but his students hadn’t taken it far enough. “What’s wrong with putting the farmer inside the building?” he asked them, remembering that at the time there were “hundreds to perhaps thousands” of empty buildings in New York City. Throughout the next decade, as he continued to teach the class, Despommier and his students developed this idea—including the use of cultivation techniques that required little or no soil—culminating in the 2010 book, “The Vertical Farm: Feeding the World in the 21st Century.”

The concept proved popular and has been widely implemented. There are now more than two thousand vertical farms in the U.S. alone, with a market value estimated at $5.6 billion in 2022.

Though retired from full-time teaching, Despommier is still thinking about ecological problems. His latest book, “The New City: How to Build Our Sustainable Urban Future,” which evolved from a course that Despommier taught at Fordham University, is a manifesto for the future of cities on a warming planet. As Despommier notes, the world’s cities make up two per cent of the Earth’s surface but produce sixty per cent of the planet’s greenhouse emissions. And cities are likely to continue growing. It is estimated that, by the middle of this century, sixty-eight per cent of the world’s population will live in urban areas (up from fifty-seven per cent in 2021).

Last summer’s seemingly endless wildfires and extreme heat events have made Despommier’s ideas seem especially urgent. On a recent morning, I spoke with him over Zoom, where he joined from his apartment in Fort Lee, New Jersey. At eighty-three, he remains a lively, charismatic presence, even onscreen, punctuating his answers with dramatic hand gestures, rhetorical questions, punning asides, and laughter. Our conversation has been condensed and edited for clarity.

Vertical farms and other forms of urban agriculture are one of the pillars of this vision you’re putting forward for transforming the way cities are built and managed. Another pillar is the idea that cities should be constructed from wood. It seems counterintuitive to build a city out of wood when we have a deforestation problem. Why is it important to build cities out of wood?

Trees sequester carbon, harvest water, produce food, and convert sunlight into energy. Those are the four characteristics I would love a city to have. The resiliency of forests is to be emulated. And that’s the reason why I picked forests as my biomimic. I want my city to be as resilient as Earth’s hardwood forests.

The main reason why deforestation is occurring is to make room for farms. Before there was farming, which was about ten to twelve thousand years ago, we had six trillion trees. We now have three trillion trees. We’ve cut down half of the Earth’s ability to capture carbon. We’re not going to replace all of that with new trees. But if we got back up to five trillion trees, let’s say, simply by leaving the remaining forests alone and letting them repopulate and selectively harvesting, the Earth’s temperature rise would begin to slow down. And, once you’ve slowed it down, that gives you time to reflect and to prepare for these changes that are not going to go away. Replacing three trillion trees by planting them—that’s not going to work. We’ll never be able to do that. So we have to let nature do that part. And, in order to do that, we have to return a lot of farmland back to what it used to be, which was forests.

[A scientist] named Gene Likens studied what happens to a forest when you cut it down—all of it. You don’t do anything. You leave it all in place and just watch it regrow. He started those experiments in the nineteen-sixties in New Hampshire, a place called Hubbard Brook. Hubbard Brook has been continuously studied since then, for how trees and how a forest recovers from a catastrophic event, like clear-cutting. If you look at what happened when Mt. St. Helens blew, it’s almost the same thing. The great majority of the trees got knocked down by the shock wave from the explosion. If you go online and look at Mt. St. Helens today, you wouldn’t recognize it. Actually, you would. It looks like the old Mt. St. Helens! So that’s only forty years from a catastrophic event back to a harvestable forest.

There’s a history of fires burning down cities such as London and Chicago. And this summer we’ve seen the devastating Canadian wildfires. Why build out of wood when it is more susceptible to fire and decay than other construction materials?

Yeah, like concrete and steel, for instance. The concrete and steel industries have huge carbon footprints. It takes a lot of energy to make those things. There’s a tremendous release of CO2 in making concrete, and there’s a tremendous CO2 release by melting iron to make an I-beam. And, once you’ve made the I-beam, the I-beam is good for only one thing, and that’s the building that it was measured for. If you want to use it for something else, you’ll probably have to melt it down and throw it into another mold. The point is that you’re using a lot of energy this way, right?…

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