Long-read: The water in your “food miles” may be more important than their carbon emissions
Long-read: The water in your “food miles” may be more important than their carbon emissions
When we hear the words “food miles”, we imagine many things: transport emissions, food waste and supply chain resilience, just to name a few. What we don’t often spare a thought for is water. While transport - with the exception of air freight and cold chain - tends to account for a relatively small share of emissions, the movement of water within our food system is a problem with wide-reaching implications both environmentally and socially.
In this long-form blog we’re going to explore how water essentially moves from one country to another within our food (taking a UK supply chain perspective), the direction of travel, why we need to take this a lot more seriously, and discuss some potential solutions.
Terminology
The first step to wrapping our heads around the concept of importing water is the terminology. The main concepts that will be useful to you are:
- Green water is the rainwater which falls onto crop fields and is absorbed by plants.
- Blue water is water from rivers, lakes and groundwater abstracted to enable crops to grow and is either evaporated from or taken into the plant.
- Grey water is water used to dilute any pollutants caused while growing the plant to acceptable levels.
- Renewable water resources are resources extracted from places (like rivers and lakes) at a rate that they will be replenished by the natural water cycle. These are at long term risk from the change in climatic patterns.
- Non-renewable water resources are either taken from sources (like groundwater) that do not replenish or are taken at a rate that can’t be restored by the natural water cycle for a very long time. These are at huge risk from abstraction.
- Total water is the total amount of water used to produce the food from any category (green, blue and grey).
- Virtual (sometimes called embedded) water is the amount of water depleted from any source to create the product. Because the water no longer retains its original form or function, it is considered “embedded” into the product and becomes “virtual”. Virtual water is a useful proxy for assessing the risks to a supply chain.
What is the virtual water trade?
When food is produced, huge quantities of water are used up to create the final product, and much of this water is non-renewable blue water which will not be replaced with rainfall. Globally, 72% of water withdrawals are for agriculture. The water gets “used-up” in lots of different ways: it evaporates off fields, transpires out of plants, runs off into waterways, is polluted by agrichemicals or manure, and some of it is transported away in the final crop. This embedded or “virtual” water is then traded between countries in food exports and this is known as the “virtual water trade”. Let’s take Spanish tomatoes exported to the UK as an example. These tomatoes were likely grown in Almeria using groundwater to irrigate them. When you eat those tomatoes, you're using up and consuming water from Spain which will not be returned to the local water table - instead it's effectively imported into the consuming country.
The direction of travel between countries
While countries with bountiful water resources might seem to have a competitive production advantage, they’re also typically high and upper-middle income countries. While there are some notable exceptions (the Netherlands springs to mind), this economic power allows these places to become net-importers of water-rich crops and thus preserve their own resources. The average agricultural water use for low-income countries is 90%; compared to 79% for middle income and only 41% in high income countries. The economic imbalance (along with factors such as amount of sunlight) means that the direction of travel for virtual water is typically from water-scarce areas and into water-abundant ones, with rich nations receiving more than double the amount of virtual water by weight. This is the exact opposite to the “optimal direction of travel” - where the flow of virtual water is mostly from water-abundant nations and into water-scarce ones, which could help minimise water stress. It is often the very countries already struggling with water stress that are exporting the most embedded water in crops.
Why is the direction of travel an issue?
There is a trade deficit in water that is not often talked about. Due to their size, buying parties such as big international food retailers have huge purchasing power to push growers to utilise extractive practices that cause long term damage. Low regulation of these private actors within the marketplace means there are currently no incentives for them to invest in and support sustainable technologies in the exporting region - leading to over extraction. While for exporting countries the income/GDP generated from trade may be welcome, it incentivises activity which undermines domestic water (and thus food) availability. When this happens, water stress is essentially being exported from the location of food consumption to the location of food production. Indeed, the best predictor for agriculture’s share of total water withdrawals is the country’s income. In poorer countries agriculture typically forms a greater portion of GDP, forcing more of their freshwater resources to be used for agriculture, often depleting them for future generations.
Strategic exporting
However, for water-limited countries wanting to trade agricultural products internationally, there are strategies and tools that can be utilised. For example, using water resources to grow high-value (typically horticultural) crops for export and saving water by importing low-value crops (often grains), thus not using the limited water supply to grow them. Such a strategic approach would preserve water for other uses. This economic approach is used in Spain to limit net virtual water exports. Spain imports water-intensive low-economic value crops (wheat, maize and soybeans) while exporting water-intensive high-economic value commodities adapted to the Mediterranean climate (olive oil, fruits and vegetables). However this alone has not been enough to prevent water stress in the region; Spain is one of the most water-stressed industrialised countries in the world. The most recent World Bank estimate put water stress in Spain at 42.56%, a figure that expresses freshwater withdrawals as a proportion of available freshwater resources.
Another complementary approach is to invest in infrastructure that allows for more water efficient crop production such as those employed in high-tech greenhouses or plant factories. Indoor farming in a controlled environment uses much less water than outdoor farming because there is recycling of greywater and less evaporation - using less than 10% the amount of the water as traditional methods. This strategy is employed heavily in the Netherlands, which, despite its tiny size, is the second largest exporter of agricultural products by value in the world. The most recent World Bank estimate put water stress in the Netherlands at 16.38%.
Supply chain risks of inaction
Without a comprehensive strategic approach, water overuse for export risks undermining local water security. Demand for water is on the rise and is only expected to continue to climb. This is due to an expanding population, and socio-economic changes, leading to a growing appetite for water-intensive diets in new places. This is set against a backdrop of increasingly changeable water supplies leading from development and climate change. Climate change is causing the water cycle to become more extreme, with more periods of drought, heat waves and heavy rainfall. Periods of drought reduce the soil's ability to capture and hold water. And while you might reasonably expect heavy rainfall to increase water availability, actually the opposite is true as fast moving water is more difficult to capture. This is causing dry regions to get drier and wet regions to get wetter.
These shifts in water availability (especially in countries exporting large amounts of virtual water) and increasing demand from growing economies are likely to shift existing supply chains. Big changes threaten the resilience of supply chains and pose risks to global food supply. This situation highlights the need to focus on the length and resilience of virtual water supply chains, particularly for countries like the UK that heavily rely on imports for their food security. We’re already seeing the price of food rise in-line with the soaring cost of energy, it is not unlikely that water will put additional strain on food prices and as the supply chain becomes unable to absorb extra costs.
Let’s explore the UK as an example
The UK is geographically well-placed in the wet and cool North Atlantic, yet imports three quarters of its fruits and vegetables. 78% of the UK’s blue water footprint occurs overseas, with commodities from Egypt, Spain, India and South Africa having the highest potential impact. Despite the fact that Egypt has recently entered a state of water poverty, it currently exports 12% of its total available freshwater resources as virtual water. The UK is one of Egypt’s major trading partners, importing £160 million of fruits and vegetables in 2019. Spain is one of the UK’s top agricultural trading partners and considered “essential for trade in fresh produce”. However, it is the most arid country in Europe and exports over 20% of its available domestic water resources - mostly to the UK, Germany and France. Agriculture accounts for around 80% of its blue water exports. UK imports of Spanish tomatoes alone require blue water equivalent to the domestic consumption of 200,000 people.
With its abundant rainfall and temperate climate, the UK is capable of domestic production of many staple fruits and vegetables. However large amounts of fresh produce are imported. The UK could, for example, replace the aforementioned Spanish tomatoes with ones grown in UK greenhouses. However, considering whether this is the best option isn’t straight forward. Energy inputs for heating greenhouses out of season can be high. So is it better to import them from where they are grown in warm sunny conditions? If just looking at energy, maybe! But, if we also consider water usage, not just energy, the decision to import could be putting more pressure on already water stressed regions. For a long time, water hasn’t been factored into the equation. This needs to change.
What risks does this pose for UK supply chains and food security?
Because the UK relies heavily on virtual water from places that are either already or becoming water-stressed, its supply chains and food security are at risk due to disruption of water supplies beyond its borders and thus, ultimately, beyond its control. We’re already beginning to see the strains from this summer’s EU-wide drought, leading to reduced supply and rising prices.
Because of the nature of supply and demand, it is likely that the prospect of selling water intensive crops into the UK will become less attractive for major global exporters. Just as it becomes increasingly difficult to grow these crops in many exporting countries due to water stress (lowering supply), the buying power of emerging economies with looser regulations is rising in relation to the UK (rising demand). Because competition for these imports is increasing, the UK will likely need to pay more to maintain access to these markets - pushing prices up. The fall out from which will be felt most acutely by the poorest in the UK who will see their already stretched capacity to buy fresh fruits and vegetables diminish further.
How can the UK ensure a consistent, accessible & affordable food supply?
To ensure the availability of water-intensive foods in a rapidly changing world, supply chains will need to be made more resilient. This will involve increasing the proportion of water-intensive crops produced domestically, sourcing carefully from areas not already pressured by water-stress or potential stress, and, vitally, supporting suppliers to enhance their water sustainability through investment in water management resources and infrastructure. This last point is absolutely vital - abandoning water-stressed suppliers and areas is a recourse that should only be taken when all other options have been exhausted. Interventions should start from the principle that responsibility for addressing water stress lies with the consuming country. High-income consuming countries should take more responsibilities in improving the global ecological environment through regional cooperation and technical assistance. This isn’t solely an issue of ethics, it’s vital for ensuring a stable supply in the future.
If trade becomes too expensive or diminishes, we cannot currently substitute in our own country. According to Professor Tim Lang, a leading expert on food policy, improved UK food security almost certainly means raising UK food production figures from around 50% to around 80% - a level at which we could fall back on. An increase to 80% self-sufficiency might seem like a tall order but it wouldn’t be the first time we’ve done it. The two World Wars forced the UK to rethink the security of its food supply chains and thanks to the Agriculture Act of 1947 UK self-sufficiency rose from 30% in 1939 to 80% in the 1980’s.
In his book, Feeding Britain, Professor Lang has set out the broad direction for rebuilding the UK’s floundering food production:
1. More diversity of planting
2. More grain for humans and less for livestock
3. More regional horticulture
4. Reskilling farmers to growing more fruits and vegetables
But how do we get there? The barriers to appropriate home production need to be removed. We need enhanced pay and better conditions for workers, incentives, more regional targets and better infrastructure. These improved pay and conditions for workers need to be matched with equivalent margin increases for the growers themselves. Controlled environment agriculture - from greenhouses to plant factories - can be a key tool for realising many of these goals. Both are key pieces of horticultural infrastructure (as the Dutch can attest) that allow for a broader range of fresh produce to be grown either over an extended growing season or all year round. This less seasonal and more stable employment would help to keep skilled horticultural labour in the UK, alongside reversing our current import/export balance across a range of perishable crops. The year-round employment offered by vertical farms and plant factories would also make a much more attractive job prospect.
Key takeaways for local and global interventions
While the movement of water in food from areas with poor water resources to areas with good resources is a “wicked problem”, there are some solid areas of focus that can be used to break it down into more manageable chunks.
First, reduce at source
The first focal point is reducing the amount of water used in the first place. Technological advancements such as precision irrigation or controlled environment agriculture, agroecological techniques like conservation tillage, or nature based solutions can all be used to reduce on-farm water consumption. Investing into these and supporting growers to adopt them needs to be a buyer-side shared responsibility.
Optimise the direction of travel
The second point revolves around using policy interventions to reverse the direction of travel, ensuring that the flow of virtual water is more commonly from water-rich nations and into water-scarce ones. Policy should start from the principle that responsibility for addressing water stress impacts lies with the consuming country
Improve country level self-sufficiency
The final point centres around keeping more food in the country in which it’s grown. For net-exporting nations, it slows the flow of virtual water out of the country, helping to better manage water resources. For net-importing countries this improves the stability of supply, protecting it from factors beyond its control.
This is, of course, breaking this down into its most basic form. While these points might sound simple, they’re deeply intersectional and involve huge technical, political and economic hurdles. Change must meaningfully engage with wide ranging stakeholders including: water companies, growers, agricultural technology providers, retailers, governments, extension services and policy-makers.
If we want to tackle global water security, true collaboration is the only way forward for efficient, equitable and sustainable development that copes with conflicting demands while managing the world's limited water resources. For that to happen we’re going to need to start making water an international priority and measuring what matters! It’s vital that we open up informed discussions about the water trade, take its trade deficits more seriously and encourage more data transparency around water use.
This article was updated 20/06/24 to update the figure associated with water withdrawals for agriculture from 70% to 72%.
