City Research Online

Abstract

This report synthesises evidence surrounding the environmental impacts of ‘local’ and ‘seasonal’ food, comparing three related categories: local (supply chain distance and transport), short food supply chains (SFSC) (small number of intermediaries) and seasonal (produced in the natural growing season of a food). A Quick Scoping Review (QSR) was undertaken to identify evidence in the academic and grey literature, with a focus on quantified life-cycle assessments (LCAs). For each of the three categories, the literature was examined to understand definitions applied and evidence of environmental impacts, looking at both greenhouses gases as a priority and other environmental impacts. It does not examine the evidence for economic, social or other benefits, though acknowledges that these are motivating factors for many stakeholders.
From the trends research, ten key conclusions were identified. They may not apply to all food products in all scenarios, but are rather general trends:
1) ‘Food miles’ is not a suitable metric to analyse food sustainability, and being geographically ‘local’ does not guarantee reduced environmental impact;
2) Efficiency of transport is important: suppliers in ‘local’ and ‘short’ supply chains must take care to ensure that less-efficient logistics do not cancel out potential GHG savings from shorter distances travelled or alternate production practices. But inefficiencies can be mitigated, and SFSCs can be more efficient;
3) Consumer transport is as important as supply chain transport. Some alternative distribution networks encourage additional consumer car journeys to transport small volumes of food. This can be avoided through specific distribution methods and encouraging low-carbon journeys;
4) Where food is produced matters, as some regions are more productive than others. Importing from such regions can have lower environmental impacts than domestic production, though this must be balanced against economic and food security objectives;
5) There may be trade-offs between different environmental metrics – notably land use and water use – with one origin country or production method being favourable for some criteria but unfavourable in others;
6) Producing food out-of-season can substantially increase the GHG footprint, and importing from countries where it is in season (‘global seasonal’ food) is often preferable. ‘Seasonal’ is therefore a more important criteria than ‘local’ for environmental impact;
7) Air freighting food adds considerably to its carbon footprint and should be avoided;
8) Emerging technology and renewable energy may alter the conclusions relating to glasshouses and indoor production, with uses of renewables or CHP in some cases having comparable, or only marginally higher GHG emissions than production without external energy inputs. The findings should be periodically reviewed as energy grid emission intensity decreases;
9) It is important to maintain a sense of scale. Most impacts identified in the literature were evaluated for crops such as fruits and vegetables, which generally have a low emission footprint per kg of produce. What may appear large relative differences – such as that between heated and unheated glasshouses – may be, in absolute terms, small. This is important for weighing up trade-offs, particularly around food security and domestic produce;
10) More sustainable on-farm practices may correlate with ‘local’ or SFSC producers, but it is not guaranteed. If production practices are the motivation for supporting a particular supplier, they should be discussed as such.
These conclusions are formed primarily based on where evidence has been quantified, i.e. via LCA. This may miss the less quantifiable ‘cultural’ benefits associated with food purchasing decisions and how they interact with consumer preferences and behaviours in other areas of life, such as if engaging with ‘local’ food encourages people to make further changes to their diet, transport and other behaviours. More research is needed to identify the role, if any, of such cultural knock-on effects.
Based on these findings, some general guidelines for environmental purchasing decisions – such as within institutional procurement – can be suggested:
a) Favour the procurement of local/domestic food that is produced seasonally, where it is socially, economically and environmentally plausible to do so. Recognise that the food procured does not necessarily have a lower environmental footprint just because it was procured ‘locally’;
b) Import seasonally-produced food from productive areas for products which cannot be grown in the UK without unreasonable environmental and economic impacts, or where domestic production is insufficient to meet demand, prioritising most efficient transport modes and avoiding air freight;
c) For products that cannot be procured in compliance with the above constraints, explore options for alternative food products that can be produced efficiently and seasonally, without compromising on nutrition;
d) Work with producers and suppliers to adopt efficient production practices that reduce environmental impacts, both domestically and internationally, such as by prioritising producers who are able to demonstrate such production practices when awarding contracts;
e) Work with all suppliers to improve logistics and reduce transport impacts, particularly looking to support the coordination of smaller or local suppliers. Additionally, encourage lower-carbon consumer journeys.

Publication Type:	Report
Additional Information:	Available under the Open Government Licence v3.0.
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments:	School of Health & Medical Sciences School of Health & Medical Sciences > Department of Population Health & Policy
SWORD Depositor:	Symplectic Administrator

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