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FOOD WASTE
A huge environmental and societal concern
Ask someone in the street to name you causes of global greenhouse gas emssions. Perhaps you might expect them to mention industry, power production, fossil fuels, or transport. But how many of them do you think would mention food waste?
Food waste is a massive but often overlooked producer of greenhouse gas emissions. So big in fact, it has been estimated that if food waste were a country, it would be the 3rd largest in terms of emissions, behind only the US and China (1, 2).
Estimates for the exact proportion of global carbon emissions produced by the global food supply chain vary widely, and so I won't quote an exact figure here. What is clear however is that food supply forms a substantial portion of greenhouse gas contributions; estimates typically fall between 20-30% (3). This does include contributions along the entire supply chain, from land use change to that produced in packaging and processing; given that food is a basic human requirement, perhaps this large contribution seems at least partly understandable?
What is far less understandable is the proportion of emissions attributed to food that is never even used. According to a 2018 article in Science (very interesting, see link in sources at end), approximately 1/4 (26%) of "food emissions" come from food that never even hits the plate (4). Of this, around 2/3 are thought to be from food lost in the supply chain, the other third from food thrown away by retailer and consumers (4).
Clearly, as well the environmental issue, the quantity of waste food highlights a moral societal issue: the wastage of vast quantities of food when so many go hungry.
But how much food is wasted by each consumer, per day?
The most commonly used figure is that the average consumer wastes 214 kcal/day (5, 6): most recent studies have in fact claimed that this is most likely a vast underestimate (5, 7, 8)
[see these numbers in the sources at the end], especially in more developed countries with higher levels of inequality.
And remember how 2/3 of emissions from food waste came from the supply chain, not the consumers individually? The same issue for food waste. The majority of wastage occurs in the food supply chain however; around 400 kcal/person/day are thought to be additionally lost along before retail and consumer wastage (6).
According to the charity Fareshare, 4.7 million people in the UK live in severely food insecure homes. With 250,000 tonnes of food going to waste being edible each year in the UK (enough for 650 million meals), the societal and environmental benefits to reducing food waste are huge.
Check out the forum for suggestions on reducing your own food waste, and how to campaign for reduce wastage before food reaches our plates.
SOURCES
Thanks for reading. I've included a brief description of what is in each article/study, in case anyone is interested in finding out about this issue in more detail.
1) FAO Food Waste and Climate Change document: http://www.fao.org/3/a-bb144e.pdf
A short document summarising several FAO and IPCC statistics. Links at the bottom for original data sources.
2) CAIT Climate Data Explorer: https://www.climatewatchdata.org/ghg-emissions
The FAO data source for past emissions for by country. Courtesy of World Resource Institute.
3) Vermeulen, S. J., Campbell, B. M. & Ingram, J. S., 2012. Climate change and food systems. Annual review of environment and resources, 37, pp.195-222.
Widely cited review paper, heavy reading in parts but an accessible summary section at the end.
4) Poore, J. & Nemecek, T., 2018. Reducing food’s environmental impacts through producers and consumers. Science, 360(6392), pp.987-992.
Very interesting large meta-analysis ( uses lots of data from comparable independent studies) from Oxford Uni. Looked at 1530 studies and found 570 of them suitable for comparison. Doesn't just look at GHG emissions either, also a number of different ways food production impacts the environment. Also highlights high level of variability in effect on the environment between food sources, and effective ways to reduce emissions through diet. Lots of more accessible media articles (eg BBC) also reference this study.
5) Van den Bos Verma, M., de Vreede, L., Achterbosch, T. and Rutten, M.M., 2020. Consumers discard a lot more food than widely believed: Estimates of global food waste using an energy gap approach and affluence elasticity of food waste. PloS one, 15(2), p.e0228369.
Recent study from this year claiming the 214kcal/person/day figure is an underestimate: they argue 527 kcal/person/day wasted by the consumer (global average). Most useful and easily accessible parts of this are the map and table on page 8, comparing wastage estimates per country, and showing other estimates of wastage per person are far higher.
6) Kummu, M., De Moel, H., Porkka, M., Siebert, S., Varis, O. and Ward, P.J., 2012. Lost food, wasted resources: Global food supply chain losses and their impacts on freshwater, cropland, and fertiliser use. Science of the Total Environment, 438, pp.477-489.
The "most widely cited" value of consumer wastage per person per day. Also gives the value of 614kcal wasted per person in total through supply chain and consumer.
7) Hiç, C., Pradhan, P., Rybski, D. and Kropp, J.P., 2016. Food surplus and its climate burdens. Environmental Science & Technology, 50(8), pp.4269-4277.
Alternative values of consumer wastage per day: cited in the Table of (5). Estimates US consumer wastage to be 1050kcal/cap/day, 620 in China, 210 in India.
8) Buzby, J.C., Farah-Wells, H. and Hyman, J., 2014. The estimated amount, value, and calories of postharvest food losses at the retail and consumer levels in the United States. USDA-ERS Economic Information Bulletin, (121).
Another alternative estimate for the US: 1249/kcal/person/day. Authors do however note that the actual recoverable food from this is likely to be lower due to recovery costs etc. However, still illustrates the point that wastage may be far higher than 214kcal/cap/day.