What is food sustainability?
Over the years we’ve become more aware of the ways in which our daily lives impact the planet. This includes the food we eat.
In fact, global food production contributes more than one third of total greenhouse gas emissions, meaning the foods we eat have a big role to play in the health of the planet, as well as our own health.
For diets to be considered sustainable, they must be able meet our nutritional needs without depleting the earth’s natural resources and compromising the ability for future generations to meet their own needs.
Making food more sustainable can involve action at the national level through policies which alter the supply chain and production processes, and at the individual level through the choices we make in our day to day lives.
But we know that making sustainable dietary choices can be really confusing. So, what impacts do our foods actually have on the planet, and how can we measure them?
In this blog, we demystify some of the most common sustainability metrics, and explore some of the possible trade-offs to be made to achieve healthy and sustainable diets.
How is food sustainability measured?
Sustainability is complex and there are lots of different metrics which aim to capture the many impacts our activities have on the planet. Food production can have a negative impact on the planet right across the farm to fork journey.
Here we explain 3 of the most familiar food sustainability metrics; what they mean, why they are important, and how they are measured.
1. Greenhouse gas emissions
Greenhouse gas emissions (GHGEs) are the most commonly referred to measure of planetary impact. When emitted into the atmosphere, as a result of burning and other processes, greenhouse gases contribute to the ‘greenhouse effect’ which warms the planet.
While Carbon Dioxide is the largest contributor to GHGEs, they are also made up of Methane, Nitrous Oxide and Fluorinated gases. Typically, GHGEs are presented as carbon dioxide equivalents (CO2eq) which converts the impacts of all kinds of greenhouse gases to the equivalent amount of carbon dioxide produced. That’s why the terms greenhouse gases and carbon emissions are often used interchangeably.
GHGEs occur right across the food supply chain. In 2019 deforestation to make way for farmland (particularly animal grazing) was the biggest contributor to agricultural GHGEs globally. Furthermore, the chemicals and energy used to run agricultural machinery, to produce fertilisers, and to process, package and transport foods, all contribute to greenhouse gas emissions.
2. Water use
Water use is measured in volume over a specified time (e.g. km3/year) and can cause stress and scarcity across the globe. There are lots of different definitions of water use, including freshwater (water from rivers, lakes and streams), blue water (water in the oceans) and green water (rainwater). The importance of each will depend on local context.
With agriculture contributing to an estimated 85% of global water use, water scarcity is most problematic in drought-prone developing countries where crop failure puts people at risk of malnutrition. As a result, water use metrics are often weighted according to a region’s relative water scarcity, helping to contextualise the regional impacts of water use.
Water use can directly affect aquatic organisms and the viability of on-land ecosystems too. Minimising water use is therefore important to maintaining viability of food production and preserving biodiversity, which is vital to supporting life on our planet.
3. Land use
Land use is the total area of land used for food production multiplied by the number of years occupied (e.g. m2 per year). This can be further split by how the land is used such as cropland, pastures and grasslands. Land use impacts the planet contributing to loss of habitats (e.g. deforestation to accommodate agricultural crops), and the loss of carbon-capturing trees.
It is estimated that 43% of the world’s ice- and desert-free land is used for agriculture, 87% of which is food production. Of that, around 83% is used for meat production. When you account for the land occupied by the animals and to grow the crops which feed them, raising livestock is a rather land inefficient process.
The land we use for growing foods comes with a huge opportunity cost; that is the environmental cost to our planet of the natural resources which could inhabit the land if it weren’t being used for agriculture.
Do sustainability metrics tell the whole story?
Using an approach called Life Cycle Analysis it is possible to estimate the total environmental impact of a product from production to end use. Yet, sustainability metrics for foods typically go only as far as the retail environment, meaning they are likely to under-estimate total impact as they don’t account for home-cooking.
Furthermore, metrics are typically presented as a population-level average. By taking into account the amounts of products imported from different countries and the environmental impacts of production and transport, they estimate the average impact of a given product. So, while they’re a really useful indicator of a population’s planetary footprint it can be harder to understand what this means for individual people and individual food products.
What’s more, it’s possible to contribute highly to one metric and minimally on another, meaning the most sustainable choice isn’t always obvious. For example, if we use data from Poore and Nemecek combined with UK trade statistics to compare 1kg of cows’ milk with 1kg of almonds, we see that cows’ milk produces 7.13kg CO2 equivalent, while almonds produce just 0.16kg. However, compared to cows’ milk, almonds are hungry for land (8.36 vs 4.91 m2 land/year) and thirsty for water (5402 vs 1141 kilolitres of water per year), making the argument for swapping cows’ milk for plant-based almond milk less clear.
What are the trade-offs for achieving sustainable diets?
The term ‘sustainable diets’ is highly nuanced meaning there’s no single definition of what constitutes sustainable food. Without careful thought, achieving dietary sustainability could have unintended negative consequences elsewhere. There are a number of trade-offs which must be balanced, including:
a) Different sustainability metrics:
Reducing the impact on one sustainability metric may inadvertently increase another. The relationship between metrics is also context specific. For example, the impact of beef (chart below) is typically highest in Latin America due to the use of deforested land and high water use to keep pastures lush.
Plus, while carbon emissions (GHGEs) are a commonly accepted sustainability metric they don’t tell the whole story. A recent study from Denmark highlights that too much focus on carbon could actually be harmful in some contexts. For example, researchers showed that the release of toxic substances into the air is unrelated to carbon emissions, indicating GHGE reduction strategies would not rid the atmosphere of other harmful chemicals.
The current cost-of-living crisis in the UK has highlighted the importance of ensuring a sustainable food supply which is affordable for everyone. So why does sustainable eating feel so expensive? Taking beef consumption in America as an example, a recent article highlights how the economics of scale is one of the factors which makes highly processed products like hamburgers so affordable, while more sustainable plant-based options may price lower income consumers out.
But sustainability doesn’t have to cost more. A study from the University of Oxford revealed that following a vegan diet could save you up to a third on your food bill. However, what you save in money you’ll likely spend in time as the study focused on whole foods rather than processed foods and restaurant meals. Meaning affordable sustainable diets are not equally accessible to all, with the most time-poor likely to find themselves digging deeper into their pockets.
c) Nutritional quality:
As the global population grows the need for additional calories to avoid malnutrition will become increasingly important. But simply producing more food may not be the answer. To fit our definition of sustainability, foods must meet our nutritional needs by providing quality calories which don’t damage the planet.
Research shows that eating less meat (particularly red and processed meat) reduces our risk of heart disease and some cancers. Plus, it’s better for the planet too. A study from the University of Leeds also found that non-vegetarian diets contribute 60% more greenhouse gas emissions than vegetarian diets. So, improvements in human health and planetary health appear to be part of the same agenda.
But we know that when following a vegetarian or vegan diet it can be tricky to ensure you’re getting the right balance of all the vitamins and minerals you need, as well as plenty of protein.
How can individuals achieve a sustainable diet?
While they may feel like a drop in the ocean, the choices we make as individuals do matter. So how do we decide what’s ‘best’ when it’s so unclear what ‘best’ looks like? Tools such as carbon calculators and on-pack labels can help, but here are a few simple rules we can each take on board.
- Eat less meat and dairy – that doesn’t have to mean following a vegetarian or vegan diet, but by reducing meat (especially red and processed) and dairy consumption we make more space on our plates (and planet!) for plants.
- Eat more plants – variety is key, include plant-based protein sources like beans and pulses to replace lost animal proteins.
- Eat locally and seasonally where possible – this helps to reduce carbon emissions by avoiding air miles and energy or water intensive growing practices.
- Reduce plastic – buy loose produce to cut down on unnecessary plastic packaging.
What role do policymakers have to play in dietary sustainability?
It’s clear that with all that complexity to balance, our individual behaviours can only go so far. Policy is needed to drive food system change and make sustainable options more accessible, so what powers do policymakers have to improve food sustainability?
- Quality metrics – better data is needed to capture a range of metrics (not just carbon) and to reflect variation due to seasonality, country of origin and in-home cooking practices.
- Raise awareness – education tools including on-pack labelling, signage in stores and public campaigns all have a role in nudging people towards more sustainable decisions.
- Shift the system – there are a lot of ways policymakers can influence the food system to make sustainable diets easier for us to achieve. These may include land use policies, agricultural practices, international trade deals, food subsidies and company incentives – all of which are discussed in the UK National Food Strategy independent review.
Achieving dietary sustainability will take the collective efforts of individuals, companies and governments. There are a number of important trade-offs to consider to balance different sustainability metrics without unintended consequences and to deliver affordable nutritious food for all.
We all have different priorities, budgets and preferences, so making more sustainable food choices will look different for each of us. But, with just a few small changes, we each have the power to reduce the planetary impact of our diets.
You can now measure food sustainability with myfood24!