Food waste: the impact on climate change

by Hammad Kazi

With momentum around climate change campaigning unlike any we’ve seen – Extinction Rebellion, Greta Thunberg and global school strikes – the issue is at the forefront of public consciousness. Naturally, at This is Rubbish, we tend to zero in on the food waste side of things. So how much is food waste really contributing to global emissions?

The Food and Agriculture Organization (FAO) reports that about 33% of food produced for human consumption is lost or thrown away every year amounting to about 1.3 billion tons [1]; this figure reflects not only inefficiency but also apathy.  We must remind ourselves that almost a billion people around the world go hungry regularly. According to statistics published by the FAO, about 821 million people were suffering from chronic under-nourishment in 2017 [2]. In addition to this moral implication of food waste there are also economic implications: food wasted through the supply chain represents wasted resources which could have otherwise been used for better purposes. This article, however, addresses yet another implication of food waste: the impact on climate change.

There are many stages in the life cycle of a food product as it passes through a typical supply chain, shown in a very basic diagram below.

There are many intermediate steps in between each stage and there are many sub-stages within each stage as well. For example, agricultural production of wheat would require preparation and planting of the crop seeds, irrigation and maintenance of the crops. Between agricultural production and post-harvest is the process of harvesting the crop. Similarly, post-harvest itself involves handling and storage.

As intuition may reveal, food waste (or loss) can occur at each stage of the life cycle. Food is considered ‘lost’ during the first three to four stages of the cycle while it is considered ‘wasted’ in the final two stages. Fruit that falls off a conveyor belt in a processing plant will be considered ‘food loss’ while an opened tin of processed fruit that is thrown away in the household will be considered ‘food waste’. Whatever terminology is taken, the result remains the same: there is some environmental implication to this loss or wastage and the more stages that the food passes through the more the environmental impact (or carbon footprint) is associated with it. There is a certain amount of food that is lost / wasted at each stage while there is a certain environmental impact of the process during that particular stage as well. This is shown in the following figure with an estimation of global contribution of each stage of the food supply chain to food wastage and carbon footprint [3].

Even though there is about 22% of food wastage occurring at the consumption stage, the carbon footprint of this stage is very high (almost 37% of the carbon footprint of the total supply chain). This is expected; the carbon footprint of any food at the consumption stage is the sum of the carbon footprint occurring at every stage before consumption as well as during consumption and even after consumption.

Different types of food have different intensities of carbon footprint associated with them as well. This depends on the life cycle of the food; the entire process of growing, harvesting, processing and packaging varies according to the type of food and therefore different food products have different amounts of environmental impact associated with them. The following figure shows the global aggregate contribution of different commodities towards carbon footprint and food wastage (within their life cycle).

It isn’t a simple calculation though and not one that can be representative across different countries. For example, the carbon intensity of a product (such as carrots) would vary in different parts of the world according to the processes employed in the various stages of its life cycle. This is how food at the table represents an expended amount of carbon footprint which has accumulated over the entire journey that the food product has taken from the beginning. Therefore, it is critical for people to produce and consume food products responsibly as every product has already impacted the environment during its journey from farm to fork.

It is important to identify the factors that cause food to be lost or wasted at different points during the product supply chain. In developing countries there needs to be focus on reducing food loss during the first two stages of the supply chain, especially post-harvesting handling and storage. Food loss during processing is controlled as it usually affects the bottom-line of the processing industry itself. Stricter government regulations and policies are needed around the world to focus on the impact of food waste on the environment and it is important to promote technological and systems-based approaches to reduce the loss of food during the first few stages of the production supply chain.

In the developed world, more effort needs to be put in to reduce wastage at the consumption level. One model that can be used to identify and highlight different ways to help reduce food waste is the Food Waste Pyramid, developed by the food waste campaign group Feedback [4].  

The next two steps cover waste management: 

Compost & renewable energy: food that is still left over should then be sent for composting or conversion to bio-fuel

Disposal: the last alternative should be sending food waste to landfills

The environmental impact of food loss / waste is a monumental problem and its impact on climate change cannot be ignored. According to The World Resources Institute, the Greenhouse Gas (GHG) emission levels due to global food wastage were about 4.4 billion tonnes of Carbon Dioxide equivalent in 2011; if food wastage was a country it would be the third-highest emitter of GHG emissions in the world [5]. And while the wastage of food has serious moral and economics implications as well, we must not ignore the drastic consequences that it has on climate change and the environmental sustainability of our planet.

Sources and references:

[1] http://www.fao.org/food-loss-and-food-waste/en/

[2] http://www.fao.org/state-of-food-security-nutrition/en/

[3] http://www.fao.org/docrep/018/ar429e/ar429e.pdf

[4] http://feeding5k.org/businesses+casestudies.php

[5] https://www.wri.org/our-work/project/cait-climate-data-explorer

[6] http://www.fao.org/food-loss-and-food-waste/en/

[7] http://www.fao.org/3/a-bb144e.pdf