Edward Glaeser doesn’t see the point in urban farms. Well, it’s not completely true – the Harvard Professor does see educational value in them for school kids, but that’s it. Last month Glaeser wrote an interesting piece on the Boston Globe about urban farms (“The locavore’s dilemma“), where he made a very persuasive argument that urban farms actually represent an inferior alternative from an environmental point of view. His main point was that devoting scarce urban land to farms and not to people will reduce cities’ density level, which will then cause the rise of carbon emissions.
When you read the piece it makes sense, especially when it comes from a bright well-known economist such as Glaeser, who knows a thing or two about the urban sphere. So do we have here the urban version of the food vs. fuel debate? Well, not so fast.
Glaeser’s argument is very simple: When you look at the environmental costs and benefits of urban farms, the costs outweigh the benefits, mainly because “farm land within a metropolitan area decreases density levels and pushes us apart, and carbon emissions rise dramatically as density falls.” Why? Because “lower density levels mean more driving.”
Glaeser provides many figures to back up his argument but forgets two important details: First, there are options like rooftop farms or vertical farming that don’t reduce cities’ density levels at all. Second, many old industrial cities have large number of vacant lots where no one wants to live and it might take decades until these lots will be populated again. In these cities, urban farms can be an excellent interim use for these lots, contributing to their revival and helping to fill them again with residents.
Let’s look first above the ground, or more specifically to the rooftops of buildings. You’ll find there plenty of room for urban farming – according to Laurie Schoeman, director of New York Sun Works, a nonprofit group that promotes the use of rooftop greenhouses, just in New York there are 14,000 acres of unused rooftop space. Schoeman estimates that this area filled with greenhouses can feed as many as 20 million people in the New York metropolitan area.
And it’s not just New York. According to phigblog, GIS data from PASDA reveals that there are 162,000 buildings in Philadelphia with a total rooftop area of over 16,000 acres. Now I’m not sure how many acres of rooftop space are available nearby to Glaeser in Boston, but I’m sure there’s plenty of space there to grow food. One example can be found at Boston University, which has a rooftop greenhouse since the 1930s. Even at Harvard University they’re experimenting nowadays with a green roof as part of the university’s efforts to reduce its carbon emissions.
Now, this is by no means a theoretical argument. Although rooftop greenhouses are just making their first steps in the urban sphere, you can already see some successful sprouts. Only last month I wrote here about BrightFarms, a NYC-based company, which has developed a win-win model of building and leasing hydroponic farms on supermarket rooftops. As I mentioned there, the company has already signed up eight supermarket chains around the country, including three of the largest 30 national chains and four of the farms are under construction.
The second element Glaeser is ignoring is the fact that cities have vacant lots, which no one is interested in. Detroit is a well-known example (just take a look at this graph), but you can find a large number of vacant lots in many other cities, especially old industrial ones that experience processes of deindustrialization and decline of population. For example, in Philadelphia according to one estimate there are about 40,000 vacant lots.
As the authors of the book, Urban Agriculture: Food Jobs and Sustainable Cities (Smit, Nasr and Ratta) point out many of these vacant lots will not come back to life in the near future and urban agriculture can be an interim use for them. The authors mention the slogan ‘Plant First, Build Later’, which was popular in Germany after World War II when the Germans reconstructed bombed out cities. This slogan can definitely be a good fit 65 years later for Detroit and other cities that don’t have any other solution for the vacant lots.
The point is that in a perfect world, vacant lots are just undeveloped properties waiting for the right developer to build on them, but in the real world it is much more complicated. In the real world, you have cities that people don’t want to live in and the value of the property is going down. You can wait couple of decades and hope that the invisible hand will bring back these cities to life, but you can also take an active approach and use these lots for urban agriculture, creating jobs and opportunities that will encourage people to come back and helping the density level to rise again. It might be only interim solution but it’s still better than the alternative in the real world which is more years of decay.
After all, it looks like Glaeser’s dilemma is not a dilemma at all. There is a way of making sure the environmental benefits of urban farms outweigh their costs – it’s just a matter of taking all the elements into consideration and realistically looking at all the options, both on and above the ground.
Raz Godelnik is the co-founder of Eco-Libris, a green company working to green up the book industry in the digital age. He is also an adjunct professor in the University of Delaware’s Alfred Lerner College of Business and Economics.