What have you done today to lower your impact?

We are washing away the foundations of our existence on every front. It is high time we move from crashing about on the planet like a bull in china shop and find a way to go forward with intent. We must find systems of living based on sustainability. The systems and tools exist, it is up to each of us to adopt them.

Blog Archive

Monday, 14 April 2008

Food part 4 - Urban Agriculture - by Robb

Most of us rely on supermarkets, our grandparents relied on local produce supplied by locally owned markets and grew their own. Since then the food supply has been largely taken over by corporate interests. This is true in Europe and the U.S. We have Tesco, you have WalMart.

“.......the United Nations Food and Agriculture Organisation cite Belgium, France and the UK as ‘extreme examples’ where only 10 percent of retail units account for more than 80 per cent of food distribution. (Food and Agriculture Organisation, 2002) Supermarkets’ reliance on economies of scale and repeatable quality standards inevitably favours larger suppliers and the use of chemicals in preference to environmentally benign agricultural methods. In contrast urban farms and community gardens, tends to be characterised by the use of organic methods and the local sale of produce.”

Urban Agriculture (UA) allows the use of organic waste for composting reducing landfill usage as well as partially remedying the breakdown of nutrient flows which are destroying our oceans and inland waterways, nutrients in the form of oil are pumped from the ground, shipped to refineries, processed into fertilisers, shipped to the farm, sprayed on the earth, washed into the water sources and thence into the sea or transported as food to the consumer and eventually landfilled or flushed down the sewer as waste. We are eating oil. UA offers an alternative to the high food/nutrient miles paradigm of the supermarket distribution model.

This reliance on supermarkets to the detriment of local food production leaves the urban dweller, particularly the poor, vulnerable to supply issues such as price hikes due to rising costs of energy and water as well as crop failure due to drought and future energy shortages, a virtual certainty with global warming and peak oil. Additionally the poor increasingly find themselves in ‘retail deserts’ as the large supermarkets fail to adequately serve more and more poor neighborhoods after having driven the local food supply network out of business or out of town. This leaves fast food as the primary option for many of the developed worlds most vulnerable with all it’s attendant health implications. Fast food as well as other highly processed foods have impacts beyond health.

Studies done in the 70’s, sparked by the oil shortages of that era, indicate that, for example the embodied energy in a typical loaf of white bread is primarily attributable to fertilisers and transport.(Chapman 1975) Here’s how it looked at that time with a total of 5.6kWh/loaf;

8.6% shop heat and light
12.2% transport
9.4% non wheat ingredients
23.6% baking fuel
8.3% packaging
5.0% transport
2.2% packaging
2.0% other
7.4% milling fuel
1.4% transport
11.6% fertiliser
7.3% tractor fuel
0.4% other

Fertilisers and transport made up 37.6% of the energy embodied in a loaf of bread. While industrial processes have become more efficient since then, packaging and transport have increased. A study done in Britain in 2000 found that the embodied energy in the food consumed by a typical family of four household was 265kWh/m2 (Vale 2000) while the energy used by a typical house at that time was 257kWh/m2. If the energy used by the family car is included the equivalent carbon dioxide emissions of the food used by the household is roughly equivalent to the equivalent carbon dioxide emissions used in the house and for personal transport. (Kramer K.J. et al., 1999) Agriculture has a large equivalent carbon dioxide emission impact because petro chemical fertilisers release nitrous oxides which are 300 times more potent as greenhouse gases than CO2.

It has been suggested that if the UK switched entirely to food produced organically, locally and consumed in season, greenhouse gas reductions in excess of 40 million tonnes/year would result, a 22% reduction in total UK CO2 emissions. (Stanley 2002)

Until about 1920 the food produced in the US released an equal amount of energy upon consumption as the energy used to supply and produce it. By 1970 the energy used to produce food in the US had multiplied on average by a factor of 8. (Steinhart & Steinhart 1971) The energy ratio in the UK by 1968 was .2, the amount of energy derived from edibles divided by the energy used to produce it, thus for every joule of energy released by the food 5 joules were used to produce it. (Leach 1976) Neither figure takes into account packaging, transport, refrigeration, processing, and marketing.

It is also important to eat food in season. Not only have we adapted as primates to eat food in season and thus it is a more natural and healthy practice but eating only produce in season has a large impact on energy usage and thus greenhouse gas emissions. A vegetable requiring a heated greenhouse requires 57 times more energy at 37.15 MJ/kg to produce than a vegetable locally grown in an open field at 1.55MJ/kg. Even shipping produce 2000 km from a country where it is in season is preferable as it uses only 5.8MJ/kg. (Kol, Bieiot and Wilting, 1993) The easiest way to do this is to eat locally grown seasonal produce.

Locally grown can mean many things. In the context of urban agriculture or peri urban agriculture, on the periphery of town, it can mean within walking distance or short delivery haulage. At a local farmers market stall the produce may have been grown in a field on the outskirts of town and been driven in but the customers to the stall are more likely to have walked or cycled to the stall than to have driven a car. Supermarkets on the other hand, being typically situated on busy roads, are much more likely to rely on customers arriving by car in addition to international delivery of the produce itself. Additionally, the produce at the farmers stall will have less packaging and gone through less processing.

As communities practice more and more UA the amount of food miles, packaging and processing reduces even further as the food is traded house to house and neighborhood to neighborhood. Have you planted your veggies yet?

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