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Testing the assertion that ‘local food is best’: the challenges of an evidence-based approach

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Abstract

Advocates of ‘local food’ claim it serves to reduce food miles and greenhouse gas emissions, improve food safety and quality, strengthen local economies and enhance social capital. We critically review the philosophical and scientific rationale for this assertion, and consider whether conventional scientific approaches can help resolve the debate. We conclude that food miles are a poor indicator of the environmental and ethical impacts of food production. Only through combining spatially explicit life cycle assessment with analysis of social issues can the benefits of local food be assessed. This type of analysis is currently lacking for nearly all food chains.
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Author's personal copy
Review
Testing the assertion
that ‘local food is
best’: the challenges
of an evidence-based
approach
Gareth Edwards-Jones
a,
*,
Llorenc¸ Mila
`i Canals
b
, Natalia
Hounsome
c
, Monica Truninger
d
,
Georgia Koerber
a
, Barry
Hounsome
e
, Paul Cross
a
,
Elizabeth H. York
a
, Almudena
Hospido
b
, Katharina
Plassmann
a
, Ian M. Harris
a
,
Rhiannon T. Edwards
e
, Graham
A.S. Day
d
, A. Deri Tomos
c
,
Sarah J. Cowell
b
and
David L. Jones
a
a
School of the Environment & Natural Resources,
Bangor University, Bangor, Gwynedd LL57 2UW,
United Kingdom (Tel.: D44 1248 383642; fax: D44
1248 354997; e-mail: g.e.jones@bangor.ac.uk)
b
Centre for Environmental Strategy (D3), University of
Surrey, Guildford, Surrey GU2 7XH, United Kingdom
c
School of Biological Sciences, Bangor University,
Bangor, Gwynedd LL57 2UW, United Kingdom
d
School of Social Sciences, Bangor University, Bangor,
Gwynedd LL57 2UW, United Kingdom
e
Centre for Economics and Policy in Health, Institute
of Medical and Social Care Research, Dean Street
Building, Bangor University, Bangor, Gwynedd LL57
1UT, United Kingdom
Advocates of ‘local food’ claim it serves to reduce food miles
and greenhouse gas emissions, improve food safety and qual-
ity, strengthen local economies and enhance social capital.
We critically review the philosophical and scientific rationale
for this assertion, and consider whether conventional scientific
approaches can help resolve the debate. We conclude that
food miles are a poor indicator of the environmental and eth-
ical impacts of food production. Only through combining spa-
tially explicit life cycle assessment with analysis of social
issues can the benefits of local food be assessed. This type of
analysis is currently lacking for nearly all food chains.
Introduction
Concerns about the environmental impacts of transporting
food increasingly long distances prior to its consumption have
focussed on the notion of ‘food miles’ (Smith et al., 2005).
This idea, popularly understood as the distance that food
travels from farm gate to consumer, has generated consider-
able interest among environmental groups, academics, Gov-
ernment, the media, and the general public (see Frith, 2005;
Hamilton, 2006;Kelly, 2004;Smith et al., 2005). In response
to these concerns, there is a growing advocacy for food sys-
tems that reduce food miles, popularly termed ‘local food’.
Positive claims about the environmental and social ben-
efits of ‘local food’ systems are increasingly common
(Morgan, Marsden, & Murdoch, 2006;Norberg-Hodge,
Merrifield, & Gorelick, 2002). However, the concept of
‘local food’ remains ambiguous. Some 22% of respondents
in an Institute of Grocery Distribution (IGD) survey (IGD,
2006) expected local food to be produced within 30 miles
of where they lived, while others extended their notion of
‘local’ to country limits (e.g. England, Scotland or to Brit-
ain as a whole). For the majority of respondents, though,
food was considered ‘local’ if it was produced in the
same county as it was consumed.
However, distance from source is not the only attribute
that consumers associate with local food. In the IGD survey,
* Corresponding author.
0924-2244/$ - see front matter Ó2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tifs.2008.01.008
Trends in Food Science & Technology 19 (2008) 265e274
Author's personal copy
local foods were also strongly associated with freshness, and
60% of respondents gave this as the most important reason
for buying local food. Other reasons included support for lo-
cal producers (29%), environmental concerns (24%) and
taste (19%) (IGD, 2006). These data are consistent with
other studies which report that local foods are equated
with safe, pure and natural foods, whilst imported foods
are more likely to carry the connotation of being impure
and unsafe (Draper & Green, 2002; La Trobe, 2001; Nygard
& Storstad, 1998; Weatherell, Tregear, & Allinson, 2003;
Winter, 2003).
Debates around local food have been given a new signif-
icance in the light of the responses of industry and Govern-
ment to climate change and their desire to calculate the
carbon footprints of goods and products. The carbon foot-
print of a food item is the total amount of greenhouse gases
(GHGs) emitted during its production, processing and retail-
ing (the most important GHGs derived from agriculture are
carbon dioxide (CO
2
), methane (CH
4
) and nitrous oxide
(N
2
O)). As these GHGs have different effects on the radiative
forcing (global warming potential, GWP) of the atmosphere
relative to the effect of CO
2,
they are converted to CO
2
equiv-
alents; with 1 kg of CH
4
being equivalent to 25 kg of CO
2
,
and 1 kg of N
2
O equivalent to 298 kg CO
2
over a 100-year
time horizon (IPCC, 2007).
1
Once the carbon footprint for a food item has been esti-
mated, it is possible to use this to inform both food chain
professionals and consumers about the relative impacts of
different products. In the latter case, a carbon label could
act in a similar way to other food labels (Kaiser & Ed-
wards-Jones, 2006), on the assumption that concerned con-
sumers will preferentially purchase goods with the desired
characteristics, here a low carbon footprint.
In summary, the argument in favour of increased localisa-
tion of food chains assumes and reinforces an association be-
tween localness, taste, naturalness, safety, nutritional value,
environmental quality and local economy. Thus, advocacy
for ‘local’ food suggests that it is generally better overall
to consume local food than food produced ‘non-locally’.
However, a priori reasoning would question the universality
of such claims, as every location is local to someone, but all
locations are non-local to most people. The local food argu-
ment implies that eating an English grown carrot in England
is better for the environment, the consumer and society than
eating a Moroccan grown carrot in England, and vice versa.
But consider a hypothetical consumer, living on an island in
the Atlantic Ocean equidistant between Morocco and En-
gland, who wants to buy carrots and has the choice of either
English or Moroccan at the same price ewhich should she
choose? A rational scientific outlook would suggest that
there must be an objective answer to this question, and
that by collecting evidence, a rational decision could be
made. This reasoning would be equally applicable to a
London consumer faced with a choice between an Essex
and a Kent grown carrot, and indeed could be extended to
the general case of all consumers. That is to say, there
must be a portfolio of evidence that could be collected which
would indicate which food item is the ‘best choice’ in any
given situation, where ‘best’ may variously be defined as
the most ethical and/or that which maximises social welfare.
If the evidence in this portfolio clearly showed that local
food was best, then this would have profound implications
for food production. However, if the opposite were true
then some of the current marketing and media focus on local
food may prove to be inconsequential.
This paper discusses the portfolio of evidence that would
need to be gathered in order to decide which type of food
chain is ‘best’. The paper primarily focuses on evidence re-
lated to biological and physical characteristics of food
chains, and does not present any analysis of issues related
to economics of comparative analysis and the benefits or
disbenefits of international trade (for further information
on these issues see Southgate, Graham, & Tweeten, 2007).
The paper begins by considering the contribution of local
and ‘non-local’ food to climate change, and then proceeds
to consider other environmental and social issues. There is
a particular focus on the case of fruits and vegetables, as
this is a sector of high public interest. While most of the
issues discussed are of generic interest, there may be impor-
tant differences between fruits and vegetables and other
foods, and any generalisations should be made with caution.
2
Greenhouse gas emissions from the food chain
Between 1850 and 1990, worldwide changes in land use
and management led to the release of an estimated
156 Pg C to the atmosphere (Houghton, 2003) (which is
about half that released from the combustion of fossil fuels
over the same period). Increasing public awareness of the
consequences for climate change, as well as the media
driven ‘food miles’ debate and the potential for commercial
advantage, are propelling the introduction of carbon label-
ling in the food chain (PepsiCo pers. comm.). However, in
the absence of an agreed framework for calculating a carbon
label, there is the potential to draw the system boundary in
different ways. System boundaries can be defined more or
less narrowly: for example, to include only the transport
1
These are the latest conversion figures given by the Intergovernmental
Panel on Climate Change (IPCC). Previously IPCC (2001) had suggested
that 1 kg of CH
4
was equivalent to 23 kg of CO
2
, and 1 kg of N
2
O was
equivalent to 296 kg CO
2
, while before that IPCC (1995) had suggested
GWP conversion factors of 21 kg for CH
4
and 310 kg for N
2
O.
2
This paper arises from research conducted as part of the UK Research
Councils’ RELU Programme in a project entitled ‘Comparative assessment
of environmental, community and nutritional impacts of consuming fruit
and vegetable produced locally and overseas’ (RES-224-25-0044).
RELU is funded jointly by the Economic and Social Research Council,
the Biotechnology and Biological Sciences Research Council and the Nat-
ural Environment Research Council, with additional funding from the De-
partment for Environment, Food and Rural Affairs and the Scottish
Executive Environment and Rural Affairs Department.
266 G. Edwards-Jones et al. / Trends in Food Science & Technology 19 (2008) 265e274
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element of the food chain; or slightly more widely to in-
clude on-farm activities only (cradle to farm gate); or
more widely still to include on-farm activities, processing,
retailing and consumption (cradle to plate); and ultimately
from cradle to grave, which would also include waste dis-
posal. Further, uncertainty arises as both different data
and calculation methods may be used when incorporating
data into integrative methodologies such as life cycle as-
sessment (LCA). Thus, estimates of the amount of green-
house gases emitted from a food system will depend on
both the definition of the system boundary and the carbon
accounting methodology utilised (Buckwell, 2005).
Working with a narrowly defined system boundary:
transport only
It is relatively easy to estimate GHG emissions from
within a narrowly defined system which includes only trans-
port, as the levels of relevant emissions are well known
(Table 1). Air freight is an area of particular public concern
as it has a large global warming potential per tonne kilometer
(i.e. the GHG emissions associated with moving 1 t of goods
a distance of 1 km). Because of this, even when relatively
low volumes of food are transported by air, their environ-
mental impact may be relatively large (Marriott, 2005).
Widening the system boundary: life cycle assessment
A wider system boundary would consider all stages of
the food chain, and LCA is a commonly used methodology
for integrating and analysing material and energy flowing
into and out of such a system (Fig. 1). When considering
GHG emissions, LCAs generally consider both the direct
emissions from activities like transport, alongside those
generated during the manufacture of the relevant inputs,
e.g. fertiliser, pesticides, electricity and machinery. It is ev-
ident from LCAs published in the peer reviewed literature
(Table 2) that for many field grown crops the manufacture
of fertiliser tends to be one of the on-farm inputs with the
greatest energy demand and GHG emission factor (Roe-
landt, Van Wesemael, & Rounsevell, 2005). However, in
glasshouse production, direct use of electricity for heating
and lighting may represent the greatest energy input
(Williams, Audsley, & Sandars, 2006).
When considering local food, several LCA studies report
that local production can be more energy efficient than non-
local production, largely because of transportation savings.
For example, Stadig (1997) suggests that more energy is
used in importing apples produced in New Zealand (NZ)
to Sweden than in producing them in Sweden, even though
apple production is more energy efficient in NZ. Interest-
ingly, while Jones (2002), who is a UK-based researcher
working on the LCA of apples, reports similar results for
the UK situation, Saunders, Barber, and Taylor (2006)
who are NZ-based researchers suggest the opposite. These
contradictory results emphasise the need to utilise similar
system boundaries and methodologies when making com-
parisons between different food systems. The full complex-
ity of the apple LCA is revealed in a recent study by Mila
`i
Canals, Cowell, Sim, and Basson (2007) (Fig. 2). This
study compares the apples imported to the European Union
(EU) from NZ and other southern hemisphere countries.
Unlike the study of Saunders et al. (2006),Mila
`i Canals
et al. (2007) consider the full calendar year and the energy
inherent in storage of apples from time of production to
time of consumption. Thus, an apple produced in a UK or-
chard which is consumed in October, uses less energy than
one produced in the same orchard which is consumed in the
following August. This difference is due to the energy used
in storage between October and the following August. So
while on average the consumption of EU grown apples in
the EU uses less energy than consuming a NZ grown apple
Table 1. Direct emissions of carbon dioxide and the global warm-
ing potential (GWP) of all gaseous emissions for different modes of
transport (expressed as kilogram CO
2
equivalent)
Transport type kg CO
2
(direct)/
t*km
a
kg CO
2
eq. (GWP)/
t*km
b
Passenger car 0.191 kg/
passenger km
0.203 kg/passenger km
Van <3.5 t 1.076 1.118
Truck, 16 t 0.304 0.316
Truck, 32 t 0.153 0.157
Plane, freight
c
1.093
c
1.142
Train, freight 0.037 0.038
Transoceanic
freight
0.010 0.011
Transoceanic
tanker
0.005 0.005
a
Includes all direct emissions of CO
2
and to provide 1 t km (i.e.
including production and delivery of fuel and capital
infrastructure).
b
Includes also radiative forcing of emissions of other greenhouse
gases.
c
It should be noted that the Royal Commission on Environmental
Pollution highlights that ‘‘the total radiative forcing due to aviation
is probably some three times that due to carbon dioxide emissions
alone’’ (RCEP, 2002). Source: Ecoinvent 1.2 database (Spielmann,
Ka
¨gi, & Tietje, 2004).
INPUT OUTPUT
Machinery
Pesticides
Fertiliser
Electricity
Fuel
Farm
Food
Wastes
Pollution
Machinery
Fuel Transport Pollution
Machinery
Electricity
Storage &
processing
Pollution
Wastes
Electricity
Packa
g
in
g
Retail Wastes
Pollution
Fig. 1. Summary of typical inputs and outputs of different stages in the
food production system. Standard life cycle assessment considers di-
rect and indirect impacts of each of each of these inputs and outputs.
267G. Edwards-Jones et al. / Trends in Food Science & Technology 19 (2008) 265e274
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Table 2. Examples of life cycle assessment analyses of horticultural products which have been published in the peer reviewed literature
Country of
production
Product Main findings Reference
Europe,
South America
and New
Zealand
Apples Primary energy requirement for production in: Europe and South America was
0.4e3.8 MJ kg
1
, and in New Zealand was 0.4e0.7 MJ kg
-1
Storage for 5e9 months in Europe increases energy requirements by 8e16%
Specific farming practices introduce significant differences in energy consumption
Season of production and consumption and storage losses affect total energy
consumption
Mila
`i Canals et al.
(2007)
New Zealand Apples Specific farming practices introduce significant differences in energy consumption
(30e50%) and other environmental impacts
Fuels, fertilisers and pesticides have an important impact on many environmental
variables and careful selection of products can reduce environmental impacts
Direct energy inputs for field operations represent 64e71% of total energy consumption;
most environmental impacts are related to energy-related emissions
Percentage of total energy consumption for different inputs were: pesticide production
(10e20%), machinery manufacture (7e12%), fertiliser production (5e11%)
Mila
`i Canals et al.
(2006)
UK Apples Transportation accounts for a considerable percentage of total energy consumption in
the life cycle of fresh apples
Transportation in most cases exceeds the energy consumed in commercial apple
cultivation
Development of local production and marketing systems can help reduce transport
demand
Jones (2002)
Switzerland Apples Apple production is represented by 37.6 GJ eq. ha
1
for energy use, 4.7 kg Zn eq. ha
1
for aquatic ecotoxicity and 1.0 kg PO
4
eq. ha
1
for aquatic eutrophication
Potatoes, sugar beet and carrots have similar energy consumption and aquatic ecotoxicity
Aquatic eutrophication caused by apple production is much lower than all arable crops
because of low P-fertiliser needs
Area-related energy use is 50% higher for apple growing compared to arable crop
rotation
The key impact categories energy use, aquatic ecotoxicity and aquatic eutrophication can
be managed by keeping the inputs of machinery, pesticides and fertilisers low
Mouron et al.
(2006)
Sweden Potatoes Agricultural production accounted for almost all the emissions contributing to eutro-
phication and acidification
Agricultural production, production of packaging materials and the household phase were
the main contributors to global warming
Energy use was evenly distributed among life cycle stages
Mattsson and
Wallen (2003)
UK and Spain Greenhouse
tomatoes
Importing tomatoes from Spain to the UK during the winter is more energy efficient
than growing them in heated glasshouses in the UK
Smith et al. (2005)
Spain Greenhouse
tomatoes
Main negative impact derives from the waste of biomass and plastics Anton, Montero,
Munoz, and
Castells (2005);
Anton, Munoz,
Castells, Montero,
and Soliva (2005)
Spain Greenhouse
tomatoes
Relative impacts of pest control depend on the selection of specific pesticides and
crop stage development at the time of application
Both integrated pest management and chemical pest management could be improved
by a careful selection of pesticides
Anton, Castells,
Montero, and
Huijbregts (2004)
The
Netherlands
Greenhouse
tomatoes
Substrate cultivation with recirculation of the drainage water results in less environmental
effects per kilogram of tomatoes than soil cultivation and free drainage
Reusing the drainage water leads to a lower emission of N and P and consequently to
a much lower score for nitrification
The lower consumption of phosphate fertilisers in crops with recirculation results in
much lower scores for toxicity to water and soil organisms
These conclusions are also valid for other fruit and vegetable crops grown on substrate
The energy consumption at the glasshouse holding of natural gas and electricity has
a great share in the total environmental pressure
Nienhuis and de
Vreede (1996)
UK Sugar beet Mean impacts per hectare were 21.4 GJ of energy consumption, emission of 1.4 t of CO
2
equivalents, 3.3 kg nitrogen leached and 15.2 kg nitrogen lost to denitrification
Tzilivakis et al.
(2005)
Switzerland Several arable
crops
Energy use dominated by mechanization, use of mineral fertilisers and grain drying
Eutrophication is mainly caused by nitrogen compounds
Field emissions are of decisive importance for many environmental impacts
Nemecek and
Erzinger (2005)
268 G. Edwards-Jones et al. / Trends in Food Science & Technology 19 (2008) 265e274
Author's personal copy
in the EU, the relative benefits of so doing vary with the
season.
The results of LCAs may also be influenced by different
scales of production at the local/global level. Sundkvist,
Jansson, and Larsson (2001) studied bread production
with locally sourced flour versus bread produced in other re-
gions of Sweden, and concluded that the smaller scale of the
local mills results in reduced energy efficiency. However,
when considering other impacts apart from energy use,
Andersson and Ohlsson (1998) find lower emissions per
kilogram of bread in smaller bread-making facilities com-
pared to a large industrial bakery. Interestingly, Schlich
and Fleissner (2005) suggest that the energy efficiency of
global food systems is greater due to the increased size of
producers (i.e. ‘ecology of scale’), which counters the in-
creased energy use for transportation. However, this study
is contested by Jungbluth and Demmeler (2005), who high-
light some of the critical eand controversial edecisions
made during the analysis (e.g. direct energy consumption in-
stead of primary energy requirements; non-representative
data for regional production; inconsistent system boundaries
for the two compared systems). Further, the production
practices of producers servicing local distribution networks
may differ substantially from those of more ‘globalised’
producers servicing large retailers, and this should also be
considered in any analysis.
These studies serve to demonstrate several important is-
sues related to LCAs. Firstly, there is inherent variation at
the farm level, within a country and between seasons, which
leads to different levels of environmental impact even for
the same product. Secondly, it is only when the system
boundary of the LCA includes all phases of the food chain
that accurate estimates of impact can be obtained. Thirdly,
the outputs from LCAs may not give simple messages to
those consumers who are seeking to make informed but
uncomplicated purchasing decisions.
Widening the system boundary further: spatially
specific emissions from agro-ecosystems
Standard LCA methodologies have been largely devel-
oped within the context of engineering and physical systems,
and are not well adapted to deal with the variation inherent in
biological systems. So if LCA is to contribute to the local
food debate, it will be necessary to utilise spatially explicit
coefficients which reflect the reality of production in differ-
ent localities. While this is theoretically possible in some of
the newest LCA methodologies, severe difficulties remain in
practice, as discussed below.
Greenhouse gas emissions from on-farm activities
Emissions of CO
2
from soils represent one of the major
fluxes in the global carbon cycle, and through the biological
and chemical processes that occur within them, agricultural
soils are responsible for releasing significant amounts of
GHGs into the atmosphere (Schlesinger & Andrews,
2000). Gaseous emissions from soil are not considered by
consumers when making food choices, and even when
they are accounted for in LCAs, the assumptions made
are often incorrect. The discussion below highlights the un-
certainties which surround GHG emissions from soils and
the difficulties inherent in representing these emissions in
integrative analyses.
The release of CO
2
from soil occurs mainly from re-
spiring plant roots and from soil microbes decomposing
organic matter in soil (Farrar, Hawes, Jones, & Lindow,
2003). A second GHG, N
2
O, is produced naturally in soils
by microorganisms through the processes of nitrification or
denitrification. Nitrification is the aerobic oxidation of
ammonium to nitrate; denitrification is the anaerobic
reduction of nitrate to nitrogen gas. Both processes are
enhanced by the increased availability of nitrogen in the
soil, such as through additions of fertilisers, faeces, slur-
ries, manure, ploughed in leys, arable residues etc., all
of which have the potential to increase N
2
O emissions.
As large quantities of nitrate fertiliser are added to most
agricultural systems, the potential for emissions is large.
There are also indirect emissions of N
2
O due to the vola-
tilisation, leaching and run-off of nitrogen from managed
soils. Major sources of emissions of the third main
GHG, CH
4
, are animal wastes and severely anaerobic soils
(e.g. rice paddies), although in most agricultural systems
CH
4
is much less important as a GHG than CO
2
and
N
2
O(Conrad, 2002).
The magnitude of GHG emissions from soil depends on
an extremely diverse range of biological, chemical, physical
and management variables making measurement or predic-
tion of the net GHG budget for agricultural soils extremely
5.0
August OctoberApril
8.0
EU1
EU2
NZ
OSH
EU1
EU2
NZ
OSH
EU1
EU2
NZ
OSH
EU1
EU2
NZ
OSH
Scenarios
1.0
2.0
3.0
4.0
6.0
7.0
9.0 January
Primary Energy Use
(MJ/kg apples in retail outlet)
Median
10%-90%
Min-Max
Fig. 2. Primary energy use per kilogram of apples from European and
southern hemisphere suppliers for the different seasons. EU1 indicates
an apple produced in a country within the European Union (EU) and
eaten in the same country. EU2 indicates an apple produced in a coun-
try within the EU and eaten in another EU country. NZ indicates an ap-
ple produced in New Zealand and eaten in an EU country. OSH
indicates an apple produced in another country within the southern
hemisphere, not NZ, and eaten in an EU country (Mila
`i Canals
et al., 2007).
269G. Edwards-Jones et al. / Trends in Food Science & Technology 19 (2008) 265e274
Author's personal copy
difficult (Christopher & Lal, 2007; Kebreab, Clark, Wagner-
Riddle, & France, 2006). This also implies that single GHG
emission values cannot be ascribed to broad agricultural
system types but are moreover likely to be highly context
specific and dependent upon local conditions. This contrasts
strongly with the relatively fixed carbon emissions associ-
ated with subsequent food processing and transport/
distribution.
One major issue which is rarely appreciated, and which
fundamentally remains poorly understood, is that soils can
also be major sinks for greenhouse gases. In the case of
CO
2
, all crop plants sequester atmospheric CO
2
in photosyn-
thesis. Some of this is returned to the soil when roots die and
at the end of the season in crop residues left behind in the
fields. Both of these are important in replenishing soil organic
carbon stores. In addition, soils can also act as sinks to signif-
icant quantities of both N
2
O and CH
4
(Castaldi, Costantini,
Cenciarelli, Ciccioli, & Valentini, 2007; Chapuis-Lardy,
Wrage, Metay, Chotte, & Bernoux, 2007; Suwanwaree &
Robertson, 2005).
The net release of GHGs from agricultural soils is there-
fore a delicate balance of CO
2
,N
2
O and CH
4
gains and los-
ses across an entire growing season. Consequently, it is
important to measure all three of these gases simultaneously
to reliably estimate GHG emissions. Further, it can be ex-
pected that over a cropping cycle an agricultural field will
fluctuate from being a source to a sink for these gases. Stud-
ies have demonstrated that these net fluxes can change
dramatically within a day depending upon the prevailing
weather conditions and management regime (Wagner-
Riddle, Thurtell, King, Kidd, & Beauchamp, 1996). There-
fore, accurate estimates of GHG emissions from food
production systems require measurements to be made over
long time periods (ideally a full calendar year) on a continu-
ous, or very regular, basis (e.g. hourly). This intensity of
measurement poses severe practical challenges and is rarely
undertaken. Even if it were undertaken for a whole calendar
year, variation in weather between years may render the
results from a single cropping cycle unrepresentative of
long-term GHG emissions.
The IPCC approach to this problem was to undertake
a meta-analysis of all the available experimental data and
to produce standard emission factors, which describe, for
example, the proportion of nitrogen fertiliser that is emitted
as N
2
O from crop production (Bouwman & Taylor, 1996).
This emission factor approach is based on a limited number
of data points and is applied worldwide for agricultural
soils regardless of variations in soil characteristics, land
management or climate (Roelandt et al., 2005). This is ob-
viously a crude approach that can have little relevance to
local conditions (Smith et al., 2002). To address this issue,
many researchers have developed mathematical modelling
approaches that attempt to simulate net GHG emissions
from soil at a range of temporal (days to decades) and spa-
tial scales (field to continental level) (Levy et al., 2007;
Vuichard et al., 2007). Ultimately, however, these models
are only as good as the knowledge that underpins them
(Tonitto, David, Li, & Drinkwater, 2007). Although scien-
tific knowledge of carbon and nitrogen dynamics is far
from complete for many agro-ecosystems, simulation
models of GHG emissions from soil such as DNDC (Li,
Frolking, & Frolking, 1992) and soil carbon stocks
CENTURY (Sanford, Parton, Ojima, & Lodge, 1991) have
been widely accepted and partially validated. However, in
many situations there may be poor agreement between
modelled outputs and actual measured emissions, and further
refinement of these modelling approaches is required before
they can be used to make informed judgements pertinent to
the local food debate.
Conclusion on LCA and GHG emissions from local
food production
It is clear from the above discussion that in order to
quantify the GHG emissions from local and non-local
food, it is necessary to conduct spatially explicit LCAs
which include emissions from agricultural systems along-
side those emanating from food processing, transport and
retailing. Unfortunately, due to the many different defini-
tions of the phrase ‘local’ it remains difficult to identify
the precise scale of analysis which would best inform con-
sumers and/or policy-makers. Given the paucity of studies
published at any scale which analyse emissions from across
the entire food chain, it is currently impossible to state cat-
egorically whether or not local food systems emit fewer
GHGs than non-local food systems.
Other environmental hazards in the food chain
The impact of food production on climate change is not
the only environmental issue that needs to be considered
when comparing ‘local’ and ‘non-local’ food. For example,
in some locations horticulture can have aesthetic impacts on
the landscape through the use of glasshouses, poly-tunnels,
field scale mulches and fleeces, particularly when there is
a clustering of horticultural farms in one area. Buying
food from such areas may support these production
methods, and thereby perpetuate the visual impact.
Another potentially polluting practice relates to the use of
pesticides, and again the hazard arising from pesticides may
vary with location. The types and amounts of pesticide used
on a given crop relate to the pest and disease pressure which
vary between growing regions (BCPC, 2007). Different pes-
ticides have their own toxicological profiles, and therefore
pose different levels of hazard. In general, herbicides tend
to pose low hazards to human health, while insecticides
demonstrate higher hazards (Cross & Edwards-Jones,
2006). For these reasons, the actual hazard posed to the
environment and society from the use of pesticides varies
with location.
In addition, there are a range of other potential environ-
mental hazards posed by agriculture whose severity may
also vary with location. These include gaseous emissions,
e.g. ammonia (Havlikova & Kroeze, 2006), pollution of
270 G. Edwards-Jones et al. / Trends in Food Science & Technology 19 (2008) 265e274
Author's personal copy
surface and ground water (e.g. nitrate leaching, phosphate
pollution (Almasri & Kaluarachchi, 2007; Powers, 2007)),
soil erosion (Van Oost, Govers, de Alba, & Quine, 2006)
and impacts on biodiversity (Butler, Vickery, & Norris,
2007). These hazards are not discussed in detail here, but
they do serve to highlight that growing the same crop in dif-
ferent places will pose different environmental hazards,
which may result in different levels of impact. Further,
the importance of these impacts can only be assessed in
the context of the locality in which the impact occurs.
There is currently no study which has quantified and map-
ped the full range of environmental impacts arising from
fruit and vegetable production at a local, national or global
level. To do so would be a mammoth task, and while such
a dataset may have some value to Governments it is unclear
how consumers and producers would react to such a mass
of information.
Local food, quality and nutritional value of fruit and
vegetables
Determinants of quality
The commercial and nutritional quality of fruits and veg-
etables is determined by a range of characteristics, attributes
and properties (Schro
¨der, 2003). Commercial quality stan-
dards include cleanliness, firmness, lack of damage, freedom
from disease, colour, size and shape, freshness, appearance,
texture, aroma, consistency, origin and use-by-date (UN-
ECE, 2007). Nutritional quality relates to essential nutrients
(carbohydrates, amino and fatty acids) and biologically ac-
tive compounds (vitamins, dietary fibre, flavonoids, caroten-
oids, phytosterols, phenolic acids and glucosinolates). Both
of these aspects of quality may be affected by the various ac-
tivities that occur along the supply chain. For example, fresh
vegetables can experience deterioration in their marketing
quality during transportation due to mechanical damage
caused by handling and transit vibrations (Hinsch, Slaughter,
Craig, & Thompson, 1993). Storage can also reduce vegeta-
ble quality due to microbial spoilage and nutritional losses,
with the most susceptible nutrient compounds being ascor-
bic acid, niacin, folic acid, phenolics, carotenoids and flavo-
noids (Goldberg, 2003).
Preservation methods such as refrigeration, gas and
controlled modified atmosphere, chlorination, electrolyzed
water treatments, ionizing radiation, application of film
packaging and surface coating aim to reduce the nutri-
tional losses and to increase the shelf-life of fresh vegeta-
bles (Alzamora, Tapia, & Lopez-Malo, 2000). While
consumer knowledge of these processes may be limited,
preservation by freezing is familiar to most Western con-
sumers. The application of quick freezing technologies
combined with blanching, a thermal treatment, can mini-
mise both nutritional losses and physical damage of frozen
vegetables. Unfortunately though, freezing is not suitable
for all vegetables and cannot be used effectively to pre-
serve salad items such as endives, cucumbers and radish.
However, although frozen vegetables retain most of their
nutrients and vitamins (including ascorbic acid, folic
acid and thiamine), the freezing process does not guaran-
tee retention of the full nutritional quality of the produce.
The major risk of nutrient loss for frozen vegetables
occurs during blanching prior to freezing (Puupponen-
Pimia
¨et al., 2003). Nevertheless, blanching is a necessary
activity as it deactivates the enzymes responsible for unde-
sirable changes in odour, flavour and colour during
defrosting and reduces the microbial activity and oxidation
processes that cause spoilage.
If consumers collected produce from a farm within a few
hours of its harvest, then it could be expected that its nutri-
tional quality would be high. However, if quality was only re-
lated to time since harvest, then given that produce grown in
Kenya can be available for sale in some parts of northern Eu-
rope 24e30 h after harvest, this produce too may be of high
nutritional quality. For these reasons, it is not possible to state
categorically that locally produced fruits and vegetables will
always be of higher nutritional quality than non-local pro-
duce. Rather their quality will depend on time since harvest
and the type of processing to which they are subjected.
Thus, the characteristics of the supply chain are probably
more important in determining quality of fruits and vegeta-
bles than is the distance between producer and consumer.
Assessing impacts on health
Scientific evidence of quality differences between local
and non-local food could be derived by measuring the
chemical constituency of food from different supply chains
throughout the year. If the health status of consumers who
ate food from the different supply chains were also as-
sessed, then any changes in their health status could, in the-
ory, be related to the chemical constituency of their food.
However, such an approach faces several challenges.
Firstly, a large amount of analytical effort would be needed
in order to chemically characterise all food items from the
different supply chains. Secondly, despite a large amount of
information being available on this topic, the nutritional
quality of all fruits and vegetables has not yet been defined.
To date, around 50,000 chemical compounds have been elu-
cidated in plants (Fiehn, 2002), most of which have un-
known function in humans. Thirdly, the actual health
impact on individuals who choose to consume either local
or non-local produce could only be assessed in relation to
the rest of their diet. So any nutritional advantage gained
by eating one type of produce could be enhanced or coun-
teracted by the quality and quantity of other elements of the
diet. Finally, the relevance of this type of chemical informa-
tion to consumers is unclear. While some consumers seem
to value the claimed health benefits associated with certain
food products, sociological research suggests that con-
sumers normally have a multidimensional concept of qual-
ity which goes beyond chemical and physical variables, and
may include a range of social factors relating to the
traditions and experiences of people in the food chain
(see Parrott, Wilson, & Murdoch, 2002).
271G. Edwards-Jones et al. / Trends in Food Science & Technology 19 (2008) 265e274
Author's personal copy
Overall discussion and the role for interdisciplinarity
in the local food debate
The previous discussion has largely taken a natural sci-
ence perspective to the impacts of purchasing local and
non-local food. However, there are also a range of social
and economic factors which have not been discussed in de-
tail here. For example, an issue of concern to some con-
sumers is the impact that their purchasing decisions will
have on individual farmers, and also on the local and re-
gional economies in which the farmer is located (witness
the growth of Fairtrade produce). Whilst many consumers
may have the desire to use their purchasing decisions to
help poorer regions and nations, others may explicitly de-
cide not to buy produce from some countries for political
reasons (e.g. movements to boycott South African goods
in the 1980s as a protest against apartheid). So, when a con-
sumer decides to preferentially purchase local food, they
may explicitly be making a decision to benefit local
farmers, the local economy and the local political status
quo. However, simultaneously they are implicitly deciding
not to support farmers, regions and political systems be-
yond their locality. The cumulative impact of these deci-
sions may have implications for the wealth of producers
and the development of regions, which may in turn have
wider environmental and political impacts.
The interaction of the impacts of consumer choice on
natural and socio-economic systems highlights the inherent
interdisciplinarity of food chain analysis. If research is to
contribute to understanding the advantages and disadvan-
tages of alternative food supply chains, then social and
natural scientists must work closely together. However,
both sets of scientists need to recognise each other’s
perspective.
For example, natural scientists may argue that it would
be almost impossible to develop a scientific dataset which
would enable formal testing of the hypothesis that local
food is better than non-local food. The difficulties associ-
ated with this task relate firstly to difficulties in defining
each locality in a spatially explicit manner ewhich is a nec-
essary step if relevant environmental data are to be col-
lected eand secondly to the large volume of data needed
to enable all localityelocality comparisons to be made
for all relevant variables. However, social scientists may
not be surprised that reductionist natural science cannot re-
solve the local food debate, as for many consumers the at-
tractions of local food do not relate to measurable
differences in its embodied energy or nutrient status, but
rather they relate to sense of place, trust and experience.
The role of natural science in the local food debate will
probably focus around informing the wider societal debate
about technical issues (e.g. energy use of different technol-
ogies) and in highlighting emerging issues (e.g. GHG emis-
sions from soil). Social science will also play a role in
knowledge discovery in fields such as risk perception, con-
sumer behaviour and social attitudes. In addition, social sci-
entists will have an important role in understanding how
decision-makers, be they consumers, the media, food chain
professionals or politicians, can best use the emerging
knowledge to guide their actions. This does not mean that
there is no role for natural scientists in communicating
knowledge, but rather that by working together, the inher-
ent synergies in natural and social science approaches can
help bring about real change in food supply chains ebe
they local or otherwise.
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... Virtuous examples at both institutional and business levels illustrate how the entire Italian agri-food supply chain is moving toward practices that mitigate social and environmental impact. However, numerous studies show that sustainability is contextdependent, varying significantly based on local agro-food systems, technologies, and community involvement [69], from seasonality and climatic conditions [70], but also from the size of the supply chain [71,72], from the type of product, production technologies, distribution, and consumption [30,[73][74][75][76]. ...
... In our work, we highlighted how sustainability must be measured in the complex interplay of its three dimensions: economic, social, and environmental [68,70,77]. In this direction, the definition of policies and the construction of a sustainable agri-food supply chain, which considers the sustainability of the entire supply chain, represent a crucial action. ...
Chapter
Full-text available
The agri-food sector is a strategic sector for Italy, fundamental to the Italian GDP (about 600 billion euros), but it is also one of the most sensitive and resilient sectors in the face of recent crises. In fact, ensuring that food reaches consumers in a safe, timely, and sustainable manner requires precise management of the supply chain. The pressures on the agri-food sector to source responsibly and sustainably in accordance with ESG criteria are increasing, especially in light of the growing awareness of ethical issues such as labor exploitation, animal welfare, and deforestation, according to the holistic One Health vision. Although the sector is subject to various risk factors, a controlled and quality supply chain, with a fair distribution of value, helps to keep the agri-food sector in step with global changes and consumer demands. Through several case studies, this work aims to demonstrate how the protection of workers’ rights, technological innovation 4.0, the streamlining of logistics, and sustainable sourcing are essential elements for a proactive approach to the company’s supply chain in managing negative impacts on people and the environment.
... The belief that local food possesses superior nutritional value because it is fresher fails to be true across all cases since the nutritional quality of produce reaches its highest point right after harvest and subsequently decreases (Edwards-Jones et al., 2010). The nutritional quality of local food depends greatly on proper handling and storage practices, including maintaining the cold chain because this aspect matches the importance of reducing the distance between farms and consumers (Edwards- Jones et al., 2008;Edwards-Jones, 2010). The nutritional content of frozen and canned produce matches fresh produce when the manufacturing and storage methods are implemented correctly (Miller & Knudson, 2014). ...
Thesis
Full-text available
The resilience and sustainability of local food systems are increasingly vital in addressing food security, economic vitality, and environmental stewardship, particularly in agriculturally rich regions like New Mexico. Youth agricultural programs, such as 4-H and Future Farmers of America (FFA) hold significant potential to enhance these systems by cultivating the next generation of producers, advocates, and innovators. This study provides a comprehensive assessment of the contributions of 4-H and FFA programs to local food systems in New Mexico, exploring their influence on agricultural education, community engagement, and the promotion of sustainable food production practices. The study adopted a qualitative method with utilization of semi-structured interviews to execute the study’s objectives to gather valuable insights on the impact of the program and the challenges faced by participants in developing a more resilient local food system. Snowball sampling technique was used to find and select eleven (11) participants from diverse group of people who have directly or indirectly engaged with local food systems in New Mexico, with emphasis on 4-H and FFA. Two (2) research objectives were posed for the study. Data were collected with semi-structured one-on-one interviews, where current and former 4-H and FFA members formed a key part of the data collection exercise. Data collected were analyzed using descriptive statistics in order to provide answers to the demographic information of the respondents. Data collected for the research objectives were transcribed and qualitatively analyzed using NVivo. Finding revealed that 4-H and FFA programs in New Mexico significantly enhance participants’ understanding of local food systems, shifting educational awareness and influencing family dynamics. By teaching practical skills like animal husbandry and marketing, the program fosters leadership and community engagement, supporting resilient, sustainable food systems, consistent with previous studies. Based on the findings, it is therefore recommended that 4-H and FFA in New Mexico should expand partnerships with schools and farms, diversify into crops and sustainability, boost visibility, enhance inclusivity, address climate challenges, offer internships, and incorporate feedback for continuous improvement to strengthen local food systems and youth engagement.
... Because of the complex global nature of food retail, all of these definitions are plausible, but refer to very different methods of production and distribution. Given this ambiguity it is not surprising that the benefits of local foods are debated within the research literature (e.g., Edwards-Jones et al. 2008). Because we were interested in the links between food production and consumption, in our research we defined 'local' relatively narrowly to mean food produced in the immediate locality (county or island) of our study areas. ...
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... Nevertheless, the idea is not to create an incontestable argument that 'local food is best' [72] and fresher [73] but rather to reframe the local-global food systems debate through a resilience lens [74,75] and to identify, experience and demonstrate multi advantages on short supply chains [76,77], such as the implementation of the principles of water-energy-food-ecosystem nexus in practice [78], the local capacity to plan food supply and security in the context of crises such as pandemics [79][80][81], or geostrategic conflicts, and to promote a just economy where local entrepreneurship may have the opportunity to succeed. ...
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... At the same time, different modes of transport result in different carbon dioxide emissions. It can therefore be misleading from a sustainability perspective to reduce the assessment of different options to food miles and to assume that "local food is best" (Edwards-Jones et al. 2008). In short, aggregation leads to a loss of information, whereas disaggregation increases the informational value content (Orcutt, Watts, and Edwards 1968;Proops 1987). ...
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