With 95 per cent of fruit and half of all vegetables consumed in the UK sourced from abroad, the debate on "food miles" is forcing processors to add the distance ingredients travel to the growing list of environmental concerns they must taken into consideration. Just how the true environmental cost of food is evaluated is still in its infancy. The term "food miles" is generally considered to be the measure of distance that food has travelled along the supply chain from farm to fork. On the manufacturing side it is an attempt to attribute the CO2 emissions along the supply chain from ingredient to product to retailer. Proponents say it is a measure that compares environmental impact among product. The longer a product is required to travel, the more energy will be required, and therefore the higher volume of emissions released into the atmosphere. Shipping fuel and the energy required for suitable storage, such as refrigeration, are part of the formula when environmental impact is calculated for imports travelling long distances. The impact of the debate has already begun to take effect, with food miles the latest marketing weapon of the UK supermarket oligopoly. Tesco now offer 'local choice' milk sourced from 14 regions around the UK. Marks & Spencer have recently introduced 'Air freighted' logos onto packaged food flown in from abroad. European countries, including Germany, are now beginning to make similar considerations in earnest as the debate on shipping food grows. However, just as food miles looked the environmental yardstick imported food would be judged by, the Soil Association threw a new consideration into the mix. It has recently published a green paper with a view to removing the organic status of food it certifies if it has been flown in. While the distance food travels is an important consideration, the mode of transport is the key consideration, according to the certifier, with air freighting being the worst offender. In the UK, where the Soil Association certifies 70 per cent of products, air freight is the fastest growing mode of transportation for imports. Less than one percent of all food imported into the UK, travels by air, but they constitute 11 per cent of all food transport emission according to Defra. Estimates put the carbon emissions from air freighting at between 40 and 200 times that of goods shipped by sea or road. Air freiting is the most expensive way to transport food, even though aviation fuel is not taxed in the UK and is about one fifth the price of petrol. The method is mainly used by importers to meet short term demand when supplies run low and to transport highly perishable goods that cannot withstand lengthy shipping durations. Evaluating the environmental impact of food by either distance covered or mode of transportation seems logical, but these methodologies have been subject to the criticisms that they are flawed and narrow. Distant importers claim a holistic approach, in which they fair better in most instances, is a better way to evaluation the total impact. Lincoln University, New Zealand published a study last year that assessed the total amount of energy required to produce apples, onions, lamb and dairy. The calculations took into consideration inputs such as fertiliser, cultivation, harvesting, as well as shipping and compared the energy used and emissions to the same products produced in the UK. The study found that lamb raised in New Zealand and shipped to the UK produced 688kg of CO2 emissions per tonne against 2849kg of emissions produced from domestically produced stock. Dairy products and apples were also found to be more energy efficient and responsible for less emissions according to the study. Although there has been some questions raised about the robustness of the figures, there is little doubt that climatic conditions and operations made imported lamb an environmentally friendlier method of producing food. Fairtrade is also a proponent of the holistic approach. The non-governmental organisation, which guarantees a minimum living wage for third world producers, opposes the food miles methodology and the air freight ban proposal. It claims that measures to focus consumers on food produced closer to home will deprive developing countries and their farmers of much needed income. Indeed if the predictions about global warming and its effects on the environment are correct, these are the very countries and people that will suffer the most. In the same week that the Soil Association published the green paper on a proposed ban on airfreighting of organic products, the UK Department for Environment, Food and Rural Affairs (Defra) announced plans to introduce a voluntary labelling system that where manufacturers would label products with their carbon footprint, including processing and transportation. A a means of backing up the labelling system, Defra is working with industry on forging a suitable mathematical formula to harmonise the calculation of "food miles" and CO2 emissions across the food industry. However, even the most comprehensive carbon footprint falls short of the true environmental impact. Quantifying the trail that starts with propagating a seed, cultivating the crop, deducting the carbon temporarily sequestered during photosynthesis, harvesting, storage, domestic transportation, international shipping and storage and packaging, distribution, retail storage, and finally the disposal and treatment of the product and packaging waste presents the industry and authorities with a morass of considerations. The energy required to collect the data and perform the calculation would presumably need to be added to any equation. The length of the trail could become interminable and inexhaustibly expensive for the food industry.