EATS: a life cycle-based decision support tool for local authorities and school caterers

Food supplies to a city are critical for its survival. They are a vital resource flow, which, together with water and energy, determine the healthy operation of the city and its people. Indeed, to understand how a city functions, it is important to understand its resource flows, and their interactions and management, to determine how an intervention to one flow would impact on another and its repercussions for city life (Lee et al. 2016).

Cities are putting increasing strains on their natural resources as they grow and develop. Populations are increasing, and in 2008, more than half the world’s population (3.3 billion) were living in urban areas (UNFPA 2014). Cities therefore have a huge influence on resource demands now and, especially, in the future, with 70% of the global population (nine billion people) expected to live in them by 2050 (OECD 2012). At the same time as the climate changes, pressures are exerted not only on food-producing areas but on urban areas that need a ready food supply, no matter what the weather conditions. Furthermore, many countries are becoming increasingly aware of the need to reduce their carbon emissions, as shown by the Kyoto protocol (UNFCCC 1997) highlighting the need for targets to tackle such emissions. Certain cities (e.g. Oxford, Birmingham, Copenhagen, Rio de Janeiro, Seoul, Johannesburg, Antwerp, Seattle) are taking the lead by setting their own more stringent targets and putting in place initiatives to achieve them. Nevertheless, the way emissions are accounted for can significantly influence the choice of initiatives set to meet carbon reduction targets.

Traditional methods of accounting for greenhouse gas emissions of countries, regions and cities have been based on activities occurring inside their geographical boundaries. This implied the exclusion of emissions produced in upstream processes located outside their borders and caused by the production of goods and services consumed by the population living within them (Larsen and Hertwich 2009). At a national level, this approach (referred to as territorial-based or production-based accounting) has been criticised for failing to account for a phenomenon known as carbon leakage (Peters and Hertwich 2007). This happens when high-income countries, due to international trade, are able to partially externalise their environmental impacts, and therefore an apparent reduction of emissions at a national level is offset by an increase outside their jurisdiction (Blanco et al. 2014; Peters et al. 2011). In the field of water resource management, a similar phenomenon has been defined through the concept of virtual water trade, represented by virtual water embedded in goods imported through international trade (Hoekstra 2003). As both climate change and resource use are driven by consumption, some authors have suggested the idea of accounting for them from a consumption perspective rather than a production perspective (Munksgaard and Pedersen 2001; Peters 2008; Peters and Hertwich 2007; van Oel et al. 2009; Wood et al. 2014).

The limitations of a territorial-based approach also apply to cities, as most of the resources consumed therein (and the related greenhouse gas emissions) originate from outside cities boundaries (Dodman 2009; Larsen and Hertwich 2009; Ramaswami et al. 2008; Vanham et al. 2016). The inclusion of embedded emissions and resources used in the production and delivery of goods and services consumed within a city has wide implications for strategies set to meet carbon reduction targets and improve the environmental sustainability of cities. Under a consumption-based accounting approach, measures would include a focus on influencing consumers towards sustainable purchasing choices or promoting material recycling and conservation through, for instance, information campaigns (Erickson et al. 2013; Munksgaard and Pedersen 2001; Ramaswami et al. 2008), alongside more traditional (and yet very important) strategies such as improving the energy efficiency of the building stock, improving the public transport system, and improving the efficiency of both urban water management and waste management.

Food consumption is a key example of the importance of accounting for consumption-based resource use and emissions in cities. A study by Vanham et al. (2016), based in 13 Mediterranean cities, found that the water footprint (WF) related to food consumption of city dwellers was about 30 times higher than their direct urban water use. In separate studies conducted for the cities of London and Oxford (UK) and San Francisco (US), authors calculated the greenhouse gas emissions from a consumption-based approach and found that food consumption accounted for approximately 20% of the total emissions in all cases (Low Carbon Oxford 2012; Riddlestone and Plowman 2009; San Francisco Department of the Environment 2013). In the case of London, this value was comparable to emissions arising from household energy use (22%) and private transport (20%). As these impacts vary significantly according to the dietary choices and the amount of food wasted by cities’ inhabitants, some cities have started to actively promote low impact diets and food waste reduction in their climate action planning (Erickson et al. 2013; Vanham et al. 2016). One example is provided by the City of San Francisco, the first city in the USA to introduce a resolution to adopt meat-free Mondays. Similarly, the City of Portland aims by 2020 to introduce food waste prevention campaigns, policies that encourage the purchase of low carbon food for public meetings and events and that leverage the purchasing power of public and private institutions to source low carbon food and educate citizens on low carbon food choices (City of Portland and Multnomah County 2009). Another example is provided by the City of Paris (France), which included the aim of sourcing seasonal, organic and local produce to be served in schools and staff canteens across the city within its climate action plan (Mairie de Paris 2007).

Current food production and consumption systems are inherently unsustainable, not least because agriculture alone is responsible for approximately 30–35% of greenhouse gas emissions globally, mainly due to deforestation, direct emissions from fertilised soils, livestock rearing and rice cultivation (Foley et al. 2011). Additionally, food systems contribute to climate change also at post-farm stage, mainly as a consequence of the use of fossil fuels and refrigerant gases (Garnett 2011). Large volumes of water are necessary to produce food: it has been estimated that agriculture is responsible for around 70% of global freshwater withdrawals for irrigation and livestock production (Foley et al. 2011) and, if water absorbed in soil is included, the estimated contribution of food consumption to total water use is nearer 86% (Hoekstra and Chapagain 2006). Furthermore, research suggests that around one third of all food produced is not eaten, due to waste and losses at every step of the supply chain (FAO 2011). This implies that the resources and emissions embedded in those products have been used and released in vain; furthermore, food waste sent to landfill is a source of methane (25 times more polluting in terms of climate change than carbon dioxide (IPCC 2007)), further contributing to climate change. These pressures are expected to be exacerbated by a growing global population, a shift to “western diets” rich in meat and processed products and the effects of climate change on agricultural production. For these reasons, it is essential to determine which drivers are important in order to design more sustainable urban food systems.

This paper focuses on the potential offered by the public food sector (e.g. schools, hospitals, universities, care homes) in reducing the environmental impacts caused by food consumption at city level, both directly—by serving low-impact food—and indirectly—by setting a good example and therefore influencing the food choices of city dwellers (Morgan and Sonnino 2007; Sonnino and McWilliam 2011). The adoption of a robust methodology and a life cycle approach are fundamental to this aim, as this can ensure that the most effective reduction measures are applied and the right information on sustainable food choices is delivered, as opposed to the adoption of measures based on “common sense myths” on sustainable food (De Laurentiis et al. 2016).

This section presents the results of the case study analysis, in which 34 different recipes of school meals are compared in terms of their CF and WF. The recipes analysed are differentiated according to whether they contain meat (M1–M13) or fish (F1–F9) or are vegetarian (V1–V12). The overall numerical results of CF and WF for all 34 recipes are presented in Table 1 and Figs. 5 and 6. For a breakdown of the ingredients used in each dish, see The School Food Plan (2015).

Figure 5 illustrates that there is a substantial difference between the CF of meals containing beef or lamb and all the other meals. Chicken-based, fish-based and vegetarian meals have comparable values of CF, which vary according to the composition of the recipe (for instance recipes containing dairy ingredients and rice have generally higher impacts than those containing pulses and other types of starches). This is in line with similar research (Chen et al. 2016) showing how a comparison between meals based on existing recipes provides more insights, and can sometimes lead to unexpected results, than a comparison across different food items on a per kilogramme basis. For instance the vegetarian lasagne, V4 (552 g CO_2e), has a 49% higher CF than the chicken couscous, M5 (370 g CO_2e). In terms of WF, fish-based, chicken-based and vegetarian recipes tend to present lower impacts, whilst pork-, beef- and lamb-based recipes present the highest impacts. One of the fish-based recipes (F1) presents the lowest value of WF (equal to 16 L) compared to the other meals analysed. This is because it is made with wild caught fish (which in the tool has WF equal to zero), whilst all the other fish-based recipes are made with farmed fish. As in the case of CF, the values of WF of some vegetarian recipes are sometimes higher than meat-based recipes, especially when they are rich in dairy ingredients or rice.

For each recipe analysed, EATS provides the user with the contribution of each phase of the life cycle to the CF (Fig. 3). The average values of the contribution of each phase calculated across the three groups of recipes analysed are presented in Fig. 7. It is possible to see how the production phase is predominant in all cases, followed by the preparation phase and the transport phase (this is in line with existing literature, e.g. Davis et al. 2010; Saarinen et al. 2012; Sonesson et al. 2005; Virtanen et al. 2011). The small influence of the transport phase is partly influenced by the assumptions made on the origin of the ingredients. As the production phase is predominant in both CF and WF, the choice of the composition of the meals is crucial to the designing of low-impact menus.

The case study presented shows how the composition of a meal significantly influences its environmental impact (both in terms of greenhouse gas emissions and of water use), and therefore highlights the potential savings achievable by applying changes to the menus. This is in line with previous research that identified menu changes as the most effective measure to improve the environmental performance of the catering sector (Cerutti et al. 2018; Jungbluth et al. 2016). However, the cultural acceptability of applying changes to school menus needs to be further investigated. A study by O’Keefe et al. (2016) identified a number of barriers to changing eating practices (including the resistance to any perceived choice restriction, and the perception that meat plays an important role in providing a nutritionally complete diet, especially for children). This suggests that less radical changes (e.g. if meat was partially replaced by an alternative source of protein 3 days a week rather than if no meat option was available for 1 day a week) would be more easily accepted by parents and pupils and would not be seen as a constraint to their freedom of choice.

The large predominance of the production phase on the CF of a meal found in this study (Fig. 7) is partly a consequence of the choice of system boundaries. The decision to define them as from cradle to plate reflects the purpose of EATS. As this tool is aimed at enabling a comparison across different menu choices, the final stage of the life cycle of a meal (i.e. waste management of plate leftovers) was not included in the analysis, as it was expected that a similar amount of plate leftovers would be generated across all meals. If this stage of the life cycle had instead been included in the system boundaries, by assuming for instance a fixed ratio of plate leftovers, this would have affected the final results in different ways depending on the waste treatment technology chosen. For instance, some waste treatment methods enable credits to be obtained (e.g. by using a waste incineration facility to generate electricity), as opposed to landfilling, which by causing methane emissions would increase the CF of the system (Silvenius et al. 2014).

In the following sections, the influence of a number of assumptions on the results is tested through two sensitivity analyses and the strengths and limitations of the EATS tool are critically discussed.

Food consumption is often overlooked when assessing the environmental sustainability of cities. This is a consequence of food being perceived as a predominantly rural issue (Pothukuchi and Kaufman 1999) and of the widespread adoption of territorial-based approaches when assessing the carbon emissions and resource use of a city. However, a number of studies have shown how, when this element is taken into account, its contribution is surprisingly, and to many remarkably, influential, with emissions being approximately comparable to those arising from household energy use and private transport. This article argues that an increased awareness and a better understanding of the implications of food choices made by city dwellers would prompt city authorities, who are almost universally seeking to reduce carbon emissions and other planetary impacts, to implement specific measures aiming at reducing the environmental impact of urban food consumption.

The research reported herein has resulted in EATS, a life cycle-based tool that provides the evidence base to support decision-makers responsible for providing school meals in the delivery of an environmentally sustainable service. The EATS tool enables its users to carry out a cradle-to-plate assessment of the carbon footprint and water footprint of a recipe with the purpose of identifying hotspots and suggesting better performing menus. The paper demonstrates the efficacy of the tool by its application to 34 meals. It compares them in terms of their carbon footprint and water footprint, showing substantial variations amongst them and a general trend of lower impacts in the case of meat-free meals. Additionally, it showed how procurement choices (e.g. seasonality of the ingredients, country of origin, transport mode) affect in different ways the final impacts of a meal. These results prove that diligence in the choice of the type of meals served by a caterer can have a very significant impact on the overall environmental performance of the service provided—simple changes that, when multiplied up and extended to food consumption in cities more generally, can have a profound influence on the planetary impacts of city living. Given that cities are striving so hard to make incremental changes elsewhere in city living (such as in the energy and transport spheres), adopting the principles generated by this research could have a major impact on the sustainability and resilience of cities.

Nevertheless, the analysis presented here only focuses on the environmental impact of school meals. It is important to recognise that the main drivers in the design of school menus are nutritional considerations and costs (Ribal et al. 2016). To achieve a holistic assessment, additional considerations need to be made to enable an evaluation of the synergies and trade-offs between the provision of economically sustainable, healthy and low-impact meals. This would represent a valuable future addition to the tool, and manifestly contribute to the health and well-being of people in cities, considerations that lie at the heart of the Liveable Cities Programme.

Moreover, although this paper has highlighted the importance of adopting a life cycle approach to understand the impacts related to urban food consumption, the research has the potential to be expanded further to incorporate other resource flows (including waste) and their interactions, at different spatial scales—a catalyst for fundamental change to a city’s urban metabolism. In the future, therefore, it is anticipated that this will contribute to more sustainable, resource-secure (hence resilient), thriving and liveable cities across the world.