Our dietary choices have a great impact on our carbon footprint, with scientists estimating our food system to contribute between 19 and 29% of global anthropogenic greenhouse gas (GHG) emissions [i]. Many factors, such as farm size, use of fertilisers, length of transportation routes, the amount of processing and importantly land use change have an influence on the carbon content of every food item. The large variations both between and within different food items is one of the major findings of a comprehensive meta-analysis on the environmental impact of various types of food performed by Poore and Nemecek (2018) [ii]. For instance, the average emissions associated with 100g of protein from beef are more than 30 times the emissions from 100g of protein from peas. At the same time, the authors found that the impact of one kilogram of beef can vary by up to a factor of 50. Therefore, the exact GHG emissions from food in general and specific food items in particular tend to be very hard to estimate. Chances are that if you find two sources that attach the same amount of GHG emissions to one kilogram of a specific food item, they are the same source. So if you find yourself confused or even a bit frustrated when trying to figure out sustainable food choices, you’re not at fault. But while it is difficult to estimate the exact carbon footprint of each one of our meals, there are some widely accepted ways that can certainly reduce the carbon footprint of our diets:
- Eating less animal products: As covered extensively in this blog post, animal products, and especially ruminant meat, are associated with much higher emissions compared to plant-based foods. Thus, even slightly reducing consumption of meat and dairy products can reduce the carbon footprint of our diets significantly.
- Seasonal beats local: Many people think that eating local is good for the environment. While that makes sense intuitively (after all, transportation causes emissions), eating local should not be our top priority. For most foods, transportation only accounts for a small share of total emissions, as can be seen in the chart below [iii]. Local beef or lamb still have many times the footprint of other foods shipped from the other side of the world. Sometimes, a local product can even be more harmful for the environment than the same product from far away: For instance, tomatoes shipped to Austria from southern Spain have a much lower carbon footprint than tomatoes grown in heated greenhouses in Austria. [iv]
- Avoiding air-freighted food: That being said, transportation is an important factor for the impact of a small group of foods – those which are air-freighted. Unfortunately, to date there is no labelling requirement for air-freighted food, which can make it difficult to spot and avoid it. On the bright side, only very little food is air-freighted, typically highly perishable and expensive food items. For Austria, commonly air-freighted goods include tropical fruits such as papayas and pineapples, vegetables like green beans and asparagus from overseas as well as fresh fish from Africa, Asia or America. [v]
- Reducing food waste: Finally, reducing our food waste can greatly improve the environmental impact of our diets. A recent report of the UN environment programme estimates that 17% of global food production is wasted – 11% in households [vi]. Since food production is associated with large amounts of GHG emissions, reducing food waste can help make our diets eco-friendlier.
[i] Vermeulen, S. J., Campbell, B. M., & Ingram, J. S. (2012). Climate change and food systems. Annual review of environment and resources, 37, 195-222.
[ii] Poore, J., & Nemecek, T. (2018). Reducing food’s environmental impacts through producers and consumers. Science, 360(6392), 987-992.
[iii] https://ourworldindata.org/food-choice-vs-eating-locahttps://ourworldindata.org/food-choice-vs-eating-locall
[iv] Theurl, M. C., Haberl, H., Erb, K. H., & Lindenthal, T. (2014). Contrasted greenhouse gas emissions from local versus long-range tomato production. Agronomy for sustainable development, 34(3), 593-602.
[v] https://www.umweltberatung.at/flugware-lebensmittel
[vi] United Nations Environment Programme (2021). Food Waste Index Report 2021. Nairobi.
Climate Footnotes 