Consumers looking to buy local meat for environmental reasons might be barking up the wrong tree, Defra's life-cycle analysis report claimed. The study looked at the life-cycle of home-grown and imported food and found substantial differences between products and between seasons.
A Defra spokesperson said: "People often link the distance our food has travelled with its impact on the environment - but often it's not that simple. As this report shows, growing methods, seasonality, storage and transport choices and other factors also play a role in a product's true impact."
The report looked at several different products, including lamb from New Zealand and beef and poultry from Brazil. It found New Zealand lamb production is less reliant on inputs such as feed and animal housing than in the UK, due to more favourable weather.
Brazilian poultry production was up to 25% less energy-intensive than in the UK, due to a lower heating requirement and shorter feed supply chains. Brazilian beef for export is generally raised on native pastures with few inputs. But growth rates in Brazil are also relatively slow, leading to higher greenhouse gas emissions from livestock methane production. Overall, the study concluded that home-production is by no means the answer to minimising food's environmental impacts.
Adrian Williams of Cranfield University, co-author of the report, said: "Food miles are not the only concern. Unless you analyse each production system from beginning to end, you do not know where the big impacts are."
A spokesperson for EBLEX, which helped with the report, said: "If we understand how the carbon footprint for beef is made up domestically and abroad, we can be better informed about how to improve our sustainability."
Yet, Sustain co-ordinator Jeanette Longfield warned that the complexity of making sustainable choices could have a negative impact. "Consumers have been told to look out for food miles, but this report tells them something different. The danger is they'll throw the baby out with the bath water."
"Shouldn't government and industry be getting it sorted out so people don't have to make those horribly complicated choices when out shopping - just take the unsustainable stuff off the shelves."
A Defra spokesman said the department would be publishing "Britain's first draft sustainability indicators for food, as part of a wider package of work on food policy, later in the summer".