In response to:Energy & Transport on Food - full article

2005-09-28T11:51:08+02:00

Food Miles and Sustainability: An Overview

The debates over food miles and associated environmental impacts and the concept of ‘sustainability’ have recently become widely discussed. We can think all of examples, such as apples from New Zealand and South Africa, strawberries from Columbia and closer to home, grapes and oranges from Israel and Spain. Here is a brief overview of the topic and the latest findings.

Over the last fifty years, there have been dramatic changes in the food production and supply chain in the UK. The most striking changes have been:
♦ Globalisation of the food industry, with an increase in food trade (imports and exports) and wider sourcing of food within the UK and overseas;
♦ Concentration of the food supply base into fewer, larger suppliers, partly to meet demand for bulk year-round supply of uniform produce;
♦ Major changes in delivery patterns with most goods now routed through supermarket regional distribution centres, and a trend towards use of larger Heavy Goods Vehicles (HGVs);
♦ Centralisation and concentration of sales in supermarkets, with a switch from frequent food shopping (on foot) at small local shops to weekly shopping by car at large out of town supermarkets.
These trends have led to a large increase in the distance food travels from the farm to consumer, known as “food miles”. Indeed, since 1978, the annual amount of food moved in the UK by HGVs has increased by 23%, and the average distance for each trip has increased by over 50%. The rise in food miles has led to increases in a wide range of factors associated with transport that affect our lives, such as environmental, social and economic burdens. These include carbon dioxide emissions, air pollution, congestion, accidents and noise. There is a clear cause and effect relationship for food miles for these burdens – and in general higher levels of vehicle activity lead to larger impacts. Growing concern over these impacts has led to a debate on whether to try to measure and reduce food miles.
One means of calculating food miles is using weighted average source distances (WASD).
WASD is used to calculate a single distance figure that combines information on the distances from production to point of sale and the amount of food product transported.
The formula for the WASD is:

where,
k = different location points of the production
m = weight (amount) from each point of production, and
d = distance from each point of production to each point of use (or sale)
Using the information on transport distance and weights of product delivered, you can calculate a WASD for each food item. Table 1 compares the WASD for locally grown produce in Iowa, USA1, with the conventional WASD for 16 typical produce types:
Table 1. Comparison of local versus conventional source WASD (food miles) for produce
Produce Type Locally grown Conventional Source Estimation
WASD (miles)
Apples 61 1,726
Beans 65 1,313
Broccoli 20 1,846
Cabbage 50 719
Carrots 27 1,838
Corn, Sweet 20 1,426
Garlic 31 1,811
Lettuce 43 1,823
Onions 35 1,759
Peppers 44 1,589
Potatoes 75 1,155
Pumpkins 41 311
Spinach 36 1,815
Squash 52 1,277
Strawberries 56 1,830
Tomatoes 60 1,569
WASD for all produce 56 1,494

Local WASD distances ranged from 20 miles for broccoli and sweet corn to 75 miles for potatoes. Overall, for this basket of food products, the ratio of the local WASD compared to conventional food sourcing was nearly 27 times greater. However, the simplicity of food miles calculated in this manner does not accurately reflect the environmental impacts of food transport.
Against this background, the UK DEFRA commissioned a study to assess whether a practical and reliable indicator based on food miles can be developed and whether this would be a valid indicator of progress towards the objectives of the government’s Sustainable Farming and Food Strategy and the proposed Food Industry Sustainability Strategy.
Key findings of the study 2 are:
• Food transport has significant and growing impacts: food transport accounted for an estimated 30 billion vehicle kilometres in 2002, of which 82% are in the UK. Figures E1 and E2 summarize the impacts
• The direct environmental, social and economic costs of food transport are over £9 billion each year and are dominated by congestion
• A single indicator based on total food kilometres is an inadequate indicator of sustainability: the impacts of food transport are complex, and involve many trade-offs between different factors. A single indicator based on total food kilometres travelled would not be a valid indicator of sustainability. To capture the complexities of the issue, we recommend a suite of indicators, which reflect the key adverse impacts of food transport (Table E3)

The total costs are very significant compared with the gross value added of the agriculture sector (£6.4 billion), and the food and drink manufacturing sector (£19.8 billion) in 2002.

Key Indicators and Trends
Based on an analysis of the key impacts of food transport, the most important trends,
and the complexities and trade-offs involved, a set of four “key indicators” is proposed.

The trends in the proposed Key Indicators for the period 1992-2002 are shown below:

While we can debate the suitability and applicability of particular sets of indicators, whatever you choose, the numbers speak for themselves. Our buying habits are adversely impacting both the world environment and the world economy and having significant social impacts at home and abroad. We need to change our habits if we want these impacts to reduce.

Go Zero

In response to:Energy & Transport on Food - full article