Page 130 - Materials Chemistry, Second Edition

Life cycle assessment and agriculture: challenges and prospects

(AEA 2005). The ‘food miles’ idea has found its potency in the ‘local versus global’ debate, 117
which is prevalent in discussions regarding food and agriculture and beyond. The essential
thesis is that food produced locally is better for the environment than that produced remotely
and transported to market. This idea has been promoted by agricultural products producers
who are under pressure from increasing imports, and from regional producers keen to estab-
lish points of differentiation between their products and more generic, distant offerings in the
marketplace. Some environmental campaigners have also linked food miles concepts to ‘anti-
industrial’, ‘anti-globalisation’ and ‘anti-corporate’ platforms.
All other things being equal, it is indeed true that food shipped using fossil fuels over low or
no distance is likely to have a lower impact than food shipped using fossil fuels for long dis-
tances. However, there are two immediate problems with this starting point. First, all other
things are invariably not equal, especially in the case of food production. Second, the implicit
assumption in this focus on transport is that the transport part of the system dominates envi-
ronmental impact. This is generally not the case in agricultural/food production systems.
The fundamental problem with the ‘food miles’ concept from an LCA perspective is that
there is no logical environmental rationale for drawing the system boundary in such a way as to
exclude all other process steps and activities except transport to market. As we have already iden-
tified in this chapter, on-farm activities and inputs are typically responsible for large portions of
the impact burden for typical foods consumed in western countries. This is not to say that trans-
port may not form a significant part of the overall impact burden, particularly where refrigera-
tion and/or aviation are significantly involved, or where small volumes of high value food are
transported long distances in complex logistics chains. However, to focus solely on transport is
an immediate and clear error from a life cycle perspective. The major UK study on food miles
puts the matter succinctly in the first recommendation of the report: ‘A single indicator based on
total food kilometres is an inadequate indicator of sustainability’ (AEA 2005).
The DEFRA study (AEA 2005) also provides case studies suggesting that tomatoes grown
in Spain may be significantly less greenhouse gas-intensive than tomatoes grown in gas-
heated greenhouses in the United Kingdom, and that for chicken meat, the mode of process-
ing and cooking may be the most significant single factor rather than transport. While the
system boundary is truncated in these short case studies, they nevertheless illustrate the
danger of using food miles as a broader environmental impact proxy. This work was con-
ducted following rising concerns about food transport concerns in the UK – concerns that
inevitably led to scrutiny of food imports from across the globe, including Australia and New
Zealand. In particular, the idea that products such as apples and lamb should be imported
from New Zealand was questioned because these are ‘traditionally’ produced domestically in
the United Kingdom. A subsequent study undertaken by staff at Lincoln University in New
Zealand summarises the ‘food miles’ debate, and compares more complete energy analyses
for food production in Europe and New Zealand, and concludes that the globally traded
products are generally responsible for lower greenhouse gas emissions than locally grown
foods in Europe (Saunders et al. 2006). Key issues identified include: chilling requirements
for extended storage of apples (since hemispheric seasons are alternate, in-season global
transport may be more efficient than domestic production with cross-season storage); and
fewer fertilisers may be required in New Zealand, where year-round grazing is also available,
avoiding a heavy reliance on supplementary feeds.
Another important shortcoming of the food miles concept is that there is no explicit recog-
nition that different transport methods generate different levels of impact. In fact, ambient
shipping by sea is relatively highly energy efficient, and thus attracts very small proportions of a
typical life cycle energy demand profile for agricultural products using this transport method
in the production system. In contrast, extended chilled transport by road, or, more significantly,

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