Strawberries, tomatoes, cucumbers – a wide range of vegetables and fruits are found in our shops all year round. Therefore, the temptation to buy food off-season is substantial – and this can cost our climate dearly.
What can you do?
- Whenever possible, consume vegetables and fruits in season – especially asparagus, cucumbers and tomatoes, where the potential for savings is greatest.
- Obtain a seasonal produce calendar so you can adjust your menus accordingly.
Those who resort to non-seasonal food products increase the CO2 footprint of their purchases many times over. In most cases, these foods have to be transported over long distances by plane or truck. But beware: sometimes they are also grown regionally, in heated greenhouses, which also require an enormous amount of energy.
Not all tomatoes are the same: In summer (July-September) tomatoes can be grown outdoors and reach the consumer via short transport routes. According to a study by Zhiyenbek, they therefore only cause 0.2 kg CO2 eq* per kilogram. In comparison, tomatoes from southern Spain cause around 2.5 times more emissions. In the winter months, however, the tide turns. This is when tomatoes from southern Spain are by far the most climate-friendly, because they can grow without any additional heat input. In Switzerland this is no longer possible and tomatoes are often grown in greenhouses with a poor climate balance. The exception are Swiss tomatoes that grow in a greenhouse heated with industrial waste heat. The same applies to the cultivation of cucumbers.
Unfortunately, consumers are usually unaware of these facts. Yet even if tomatoes from southern Spain are most climate-friendly in winter, does it make sense to purchase them? According to Proplanta, they are grown in one of the Spanish regions with the lowest rainfall, with high water and pesticides useage, and poor working conditions. Hence, the environment is best served if one buys tomatoes – or other vegetables – exclusively in-season.
About 25 percent of the green asparagus in our supermarkets are air-freighted. This is one of the reasons their carbon footprint is poor on average. Thus, it is easy to save on emissions by consuming in-season and local green asparagus: For example, imported green asparagus from Chile (air-transported) causes around 15 kg CO2 eq * per kilogram, while those from Switzerland are responsible for only one kg CO2 eq.
“Apples from New Zealand are more climate-friendly than Swiss apples” – headlines such as this have been making the rounds a lot lately. But is there any truth to them? Apples are harvested in late summer or autumn and then stored in refrigerated warehouses. Accordingly, the energy expended for storage over the coming months adds up and reaches a peak in the following summer – before the next harvest. At this point Swiss apples actually have a less optimal climate balance than apples from overseas. However, the window is short. It should also be noted that the optimisation potential for domestic warehouses (e.g. electricity from renewable energies) is much greater than for air/sea transport from abroad, as those are fossil fuel dependent.
You can find further details regarding seasonal foods on the interactive Migros seasonal produce calendar.
* CO2-equivalents: In addition to CO2, there are other gases that contribute to the greenhouse effect. However, these differ from CO2 in the length of time they remain in the atmosphere and their effect on the climate. To simplify the comparison of different greenhouse gases, their emissions can be converted into CO2 equivalents. For example, 1 kg methane has the same effect on the climate as 25 kg CO2 (IPCC, 2014). 1 kg methane therefore corresponds to 25 kg CO2 equivalents.