The Pump Handle (Liz Borkowski) and Casaubon’s Book (Sharon Astyk) are writing posts this week about the global trend of urbanization. Liz’s first article in the series is here. -KS

As I mentioned yesterday, Sharon Astyk of Casaubon’s Book and I are spending this week focusing on urbanization issues. Sharon is a farmer and has been writing for a long time about sustainable food production, particularly as it relates to climate change and a dwindling supply of fossil fuels. In her post yesterday, she linked to some of her past writing about urban issues, and the theme that ties them together is rural-urban collaboration. Cities can’t grow enough food to feed all their residents, and rural areas need the durable goods that cities produce, so a reciprocal relationship is important.

As the global supply of fossil fuels shrink and oil gets more expensive, foods that have to be shipped long distances – and particularly those that have to be refrigerated in transit – will become much harder to afford. Urban agriculture, which already seems to be undergoing something of a renaissance, will become more necessary. In “Reconsidering Cities,” Sharon points out that it other parts of the world it’s not so unusual for city dwellers to raise much of what they eat:

Hong Kong and Singapore, for example, both produce more than 20% of their meat and vegetables within the city limits. In 2002 with more than 6 million people, Hong Kong was producing 33% of their produce, 14% of the pigs, 36% of the chickens and 20% of the farmed fish eaten in the city limits, much the animals being raised on 160,000 tons annually of food waste that was recycled into meat and eggs. Will cities grow all their own food? No, but they don’t necessarily have to. A substantial portion can be enough, as long as they also build ties to surrounding rural areas.

The fact that urban livestock can be raised on food scraps is a big plus, but many cities have laws that prohibit livestock in residential yards. I can see the rationale for this; living in close proximity to lots of other people means tolerating a certain amount of noise and smells, and I’m not eager to increase those. But some cities seem to have worked out reasonable limits – for instance, according to Urban Chicken, Portland lets residents keep chickens (not roosters) provided their habitat isn’t within 50 feet of a residence; up to three chickens are allowed without getting a permit. (I picked Portland because some friends of mine moved there and soon started raving about how much they love the fresh eggs from their three backyard hens.)

My apartment building has no yard, but it does have a roof – and rooftop gardening seems to be a hot new trend, as reported by the Washington Post’s Robin Shulman. This isn’t just individual households deciding to grow a few tomato plants, but entrepreneurs investing thousands of dollars to create small farms atop buildings. Some of the large rooftop gardens are cooperative or educational ventures, but others are businesses based on a calculation that growing food closer to where it’s used creates savings that offset the cost of moving the inputs and outputs up and down several flights. Any large-scale venture must take into account the building’s weight-bearing capacity and drainage options, but Shulman rattles off examples of people making it work.

Will Farming Grow Up?

The dominant model for agriculture in the US is unsustainable. Growing crops generally means lots of chemical pesticides and fertilizers, and many farmworkers labor in unhealthy conditions. Massive livestock operations produce huge lagoons of noxious animal waste, and the animals end up in slaughterhouses where fast-moving production lines leave many workers with cuts and repetitive stress injuries. Then food travels long distances, contributing to climate change.

There are alternatives to this kind of damaging food system; organic agriculture addresses the pesticide problem, and plenty of small farmers and livestock owners are demonstrating that it’s possible to grow and process food responsibly and sell it locally – in many ways, going back to a more traditional form of farming.

There’s also an agricultural concept that addresses current agribusiness shortcomings in a more futuristic way: vertical farming. Its most visible advocate is Columbia University public health professor Dickson Despommier, who last year published a New York Times op-ed outlining his vision. Crops and livestock would grow in multi-story buildings in urban areas, close to those who’d eat them. The system would use water and waste efficiently, eliminate the need for pesticides, and be far less vulnerable to the droughts, floods, and other disasters that strike outdoor crops routinely.

Despommier goes into more detail in this essay, and presumably into even more detail in his book, The Vertical Farm: Feeding the World in the 21st Century. I know that he mentions urban job creation as one benefit of the model, and I’m curious to know whether the book discusses occupational health issues. I’d hope that vertical farms could be designed so that workers could harvest crops without kneeling or bending over rows of plants.

(A related idea to vertical farming is aquaponics, which uses waste from fish grown in tanks to fertilize plants. Some fish, like tilapia, can be fed with table scraps. Or, there’s urban aquaculture, where abandoned warehouses and vacant lots can become fish-raising sites.)

In a 2008 Science News article, Rachel Ehrenberg delves into the question of how feasible vertical farming is. She spoke to Gene Giacomellia, director of the Controlled Environment Agriculture Center at the University of Arizona in Tucson, who points out some of the challenges, like providing different climactic conditions for different crops and ensuring an appropriate and even distribution of light from an efficient source. It can be done, but can it be done cost-effectively? Other experts warn that farming, even in high-rise structures, isn’t the most lucrative use of land in places like New York, and the cost of retrofitting or demolishing old buildings to install vertical farms can be steep.

Of course, if we consider the environmental and health costs of our current food-production system, the items in the supermarket are far more expensive than their sticker prices suggest. If true costs were considered, vertical farming could be cheaper option. And as oil prices rise and the effects of climate change reduce global crop productivity, a more-sustainable system that seems pricey now might become a relative bargain. I hope some far-sighted funder supports pilot testing of vertical farming and other such innovations, so we can identify workable systems and be ready to roll them out in the decades ahead.