How your daily sandwich can feed global warming

Scientists warn that the production of our favourite lunchtime snack is creating harmful greenhouse gases

WHEN the 4th Earl of Sandwich ordered his meat to be served between two slices of bread to avoid disrupting a card game, he probably did not ponder the seismic consequences some 250 years later.

According to scientists, sandwiches have a major impact on the environment.

In fact, the worst culprit – the all-day breakfast of egg, bacon and sausage – produces the same amount of carbon dioxide as driving a car for 12 miles.

At the other end of the scale, the least polluting option is egg and cress, which generates 739 grams of carbon dioxide equivalent (CO2 eq), making it twice as green as its meaty counterpart.

For the first time, researchers studied the whole life-cycle of 40 types of home-made and bought sandwiches, from the production of ingredients to shipping and waste management.

“Given that sandwiches are a staple of the British diet as well as their significant market share in the food sector, it is important to understand the contribution from this sector to the emissions of greenhouse gases,” said Prof Adisa Azapagic, from the School of Chemical Engineering and Analytical Science at Manchester University.

According to the British Sandwich Association (BSA), more than 11.5billion sandwiches are consumed in the UK every year. That, according to scientists, generates around 9.5million tons of CO2 eq, equivalent to the annual use of 8.6million cars.

The analysis found that the highest carbon footprints are for sandwiches with pork meat, such as bacon, ham or sausages, and those containing cheese or prawns. But making the snacks at home could reduce carbon emissions by a half compared to ready-made equivalents, the study showed.

Home-made sandwiches are generally greener, as they cut out much of the supply chain and packaging.

Keeping sandwiches chilled in supermarkets and shops also contributes to their carbon footprint.

Around half are made at home and the other half are bought over the counter in shops and service stations around the country.

The study concludes that the snacks’ carbon footprint could be reduced by as much as 50 per cent if a combination of changes were made to the recipes, packaging and waste disposal.

The researchers also suggest extending sell-by and use-by dates to reduce waste. The BSA estimates that extending the shelf life of sandwiches by relaxing such dates would help save at least 2000 tons of food waste annually.