Urban Farming on a Rooftop, 34 stories high. Image Credit Lloyd Alter
Economist and author Edward Glaeser enjoys contradicting popular wisdom; I reported on his trashing of Jane Jacobs earlier; now he writes in the Boston Globe that Urban farms do more harm than good to the environment. In it he trots out the usual arguments against local food:
We must weigh the environmental benefits from shipping less food against the environmental costs of producing and storing local food in a state that doesn't exactly have ideal conditions for every kind of produce. One recent UK report found that the greenhouse gas emissions involved in eating English tomatoes were about three times as high as eating Spanish tomatoes. The extra energy and fertilizer involved in producing tomatoes in chilly England overwhelmed the benefits of less shipping. Even New Zealand lamb produced less greenhouse gases than English lamb.
We have been through this before, (Sami was yesterday!) so this is quick and easy:
The tomato study compared English hothouse tomatoes to Spanish tomatoes. It isn't relevant. The real issue is seasonal vs out of season.
Specifically, according to the Telegraph,
British farmers who grow tomatoes and strawberries often rely on heated greenhouses to produce crops outside the short fruit season in Britain. Dr Adrian Williams, an agriculture expert from Cranfield University, in Bedfordshire, said: "If you produce something in an unheated greenhouse abroad or in a field, you make a considerable saving, as you are not having to use large amounts of energy heating a greenhouse. You could expect there to be a difference even if you allow for the transport from Spain."
Except, as we have noted, you can't separate a local diet from a seasonal diet. You shouldn't be buying hothouse lettuce and tomatoes, you should be eating them when they are in season. Who says that urban farms are using heated greenhouses? If they are not, then Glaeser's reference is meaningless.
The study about the carbon footprint of New Zealand Lamb vs English Lamb is comparing apples to oranges.
Michael Shuman explains in the Ethicurian:
The July 2006 study [PDF download] compared the typical industrially grown sheep in the two countries, and showed that New Zealand's agribusiness players are a bit better in their ecological practices than their British counterparts. It's a little like saying that a new SUV contributes less to global warming than an old gas-guzzling Cadillac.
The explanation of most of the difference in the two country's carbon emissions turns out to be coal. Typical British farmers use more electricity - both directly and indirectly for the processing of its fertilizers, feeds, and additives - and are thereby saddled with the emissions from lots of dirty coal plants. New Zealand has lots of hydroelectric dams. So those poor bionic sheep in the United Kingdom inherit a huge carbon price tag. This also means that as the British move toward renewable energy sources, as they plan to do, the New Zealand carbon advantage will vanish.
Modern Cargo Ships Now Traveling Slower Than 19th Century Clippers
Then there is what I called the shipping problem.
There is no question, shipping frozen lamb by sea from New Zealand to the UK has been pretty efficient. One can say the same thing for Australian wine in glass bottles -- the last couple of miles by truck burn almost as much as the entire sea voyage.
One of the reasons shipping is so cheap is because of the fuel that cargo ships burn, but the implications of that are beginning to become apparent. Cheap, high-sulphur bunker fuel means that "Just 15 of the world's biggest ships may now emit as much pollution as all the world's 760 million cars".... What will happen to the economics of shipping if carriers have to switch to diesel, at twice the price of bunker fuel? What happens to the price of diesel when ships are competing for it?
Shipping that lamb is cheap only because it doesn't include the externalities, such as the cost in soot and pollution from burning the crap from the bottom of the barrel. Factor that in, and the local UK lamb begins to look a lot better.
Urban Farming in Detroit Helps Families Survive (Video)
Finally Glaeser trots out a new argument, that doing urban farming would half the density of our cities, at great cost to our carbon footprint.
The increased gas consumption from moving less than a tenth of agricultural farmland into metropolitan areas would generate an extra 1.77 tons of carbon dioxide per year, which is 1.77 times the greenhouse gases produced by all food transportation and almost four and a half times the carbon emissions associated with food delivery.
But I have not heard anyone, anywhere, discuss doing urban farming on land that might otherwise be developed for higher density living. I have heard of farming in Detroit (which has already lost half of its density), on rooftops, even in vertical farms. But nobody has suggested farms instead of people.
If this is the best argument that can be made against urban farming, then the movement doesn't have much to worry about. Read it all in the Boston Globe
More on Local Food:
Stop Eating Fossil Fuels, Start Eating Food
Local is Better, and Its Not Just About the Carbon