Food
Miles
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FOOD
MILES
A
Farmscape Ecology Program
Consumer Education Project
'Food Miles' refer to the distance that your food has been transported
between its source farm and where you buy it. (Actually, you should add
the distance from store to home onto that mileage or else eat it in
your car or use a bicycle.) Food miles are one measure of the amount of
energy used to transport your food and the consequent pollutants
released by that transport. Estimates vary but transport may account
for 10-20% of the total energy use associated with the provision
of a given food item. Foods with much higher total energy input (e.g.,
grain-fed meat) have a lower proportional transport
cost (say, <10%), while foods requiring relatively low inputs
and no
preparation (e.g., fresh apples) have a higher proportional transport
cost (e.g., >50%).
As such, Food Miles are a relatively simple
(yet certainly incomplete) statistic that can be used to demonstrate
the ecological importance of
local foods. They can also serve as an indicator of "localicity",
which, in turn, may be tied to socio-economic aspects aside
from
those related to energy use. As the numbers above suggest and a recent
debate in the press has highlighted (e.g., recent NY Times commentary),
food miles alone do not fully describe the energy consumption and
resulting pollution associated with a foods 'life cycle'. One can come
up with scenarios under which a distant food has a lower overall energy
requirement than a similar local one. This was done in the
study
at the heart of the NYT article. Researchers found that for a
Brit
pasture-raised New Zealand lamb was more energy conscious choice than
the native grain-fed British lamb. True enough, although, as
others have pointed out, locally and organically
raised
British lamb would, due to the transportation, likely win out over the
New Zealand equivalent. Furthermore, examples of foods for which
transport costs are a key determinant of the most ecological choice are
well-documented if less frequently cited of late.
A full Life-Cycle Analysis of the energy-use and pollution consequences
of a food would certainly paint the most complete picture of its
environmental repercussions. However, those calculations are complex
and daunting. Although one English supermarket chain has said it will
calculate the carbon footprint of all its foods, food miles remain a
useful statistic for us mere mortals and, as mentioned, also serves to
describe how local a food is, a factor with broader implications. The
issues highlighted in the paragraph above suggest that we should not be
too lazy in the accepting food miles as a complete descriptor of food
quality, but it's a worthy descriptor just like all the nutritional
details appearing on a packaged food.
The Farmscape Ecology Program has been developing an
in-store food mileage education and research program to help customers
understand this aspect of their purchasing habits. Our goal is to make
each customer (or at least some customers) informal sociological
researchers, giving them the tools to follow and change their own
buying habits. We want to provide them with the information and
incentives to reduce their dependence on non-local foods.
Any move towards increased marketing of local foods will need to be a
two-way process with markets providing the possibility for such
purchasers and customers providing the demand. Our emphasis is not on
creating guilt (which might deter customers), but rather on presenting
the issue and then proposing the purchase of local foods as an
attractive and highly possible solution. To help encourage this
process, we have designed several tools. You are invited to review the
materials provided here and give us your feedback. Thanks!
For further information on these concepts, we highly recommend the
work of Rich Pirog and associates, and the detailed
discussion presented by the Life Cycles Project.
However, please note this is a WORK IN PROGRESS. If you're
missing something, please
email us.
Our Food Mileage
Tools (click on the title link for more information):
The
Green Checkout Report -
The idea is to give each interested customer feedback on their
purchases - their average food mileage and the associated energy use
and pollutant production. In addition, we also provide information on
their contribution to local economics and a map of their purchase
sources. This is a rather complex form that may only be used in
conjunction with educational programs. Currently, we are exploring the
possibility of simply adding food mileage to the traditional register
receipt, and then providing incentives for reducing that value. The
form shown in this link is now the "second edition", we tried to revamp
our earlier, drier, more number-heavy report into something that was
more positive and more directly related to encouraging local purchases.
Mockup
of Green Checkout Receipt (the
image has sufficient resolution so that it can be enlarged and read)-
While the above report has lots of info., it's probably unrealistic
to assume that any store would ever consider printing it out for their
customers. But how about just incorporating the food miles info. into
the store's receipt? While we haven't conquered all the technological
glitches of integrating such information into a POS (point-of-sales)
system, it should not, theoretically at least, be difficult. POS
systems are the industry name for those checkout systems that spit out
a total and receipt after your items have been scanned. This draft is
still a bit nerdy but heck, if you're going to read your receipt... The
poster which has been miniaturized in
this link explains how to read the receipt, values used in
the calculations are listed in the caveats below.
A Map
Study of the New
York City Foodshed
(8 MB pdf file) This is a series of maps that we assembled
illustrating the
location of various farms or other food producers who sell in NYC via
Farmers' Markets or CSA's. The maps help explore the factors affecting
the locations of these farms. They are meant to illustrate, in part,
the importance of understanding one's foodshed not just as the area
from which food 'flows' to a given point (e.g., NYC) but also as the
area where farm production is affected by 'flow back upstream' from
that given point.
Excel Spreadsheet for Food
Mile Checkout Receipt
- This spreadsheet prints out the above receipt. It
is meant to
help teachers (or even retailers who want to teach) explore food miles.
It is somewhat
clumsy but I am working on annotating it. This link gets you to a more
detailed description of the spreadsheet and a download for it.
Updates, corrections and alternate versions are welcome. We'll be glad
to post additional versions so that they can shared.
Food
Miles Poster - Illustrates roughly how much gas and
carbon
dioxide are used by various food transport methods.
To
download a 90 MB
tiff version of this poster, click here.
What Food Miles Can & Can't Tell You Poster.- Food
Miles aren't the whole story, but they are part of the story. This
poster is meant to communicate that.
To
download a 90 MB
tiff version of this poster, click
here.
Some
Caveats:
There are a few cautions that need to be included when discussing this
issue and these calculations.
1) As noted, transport is almost never the largest block of energy use
associated with a product. Even with organic produce, substantial
fossil fuels are often used during cultivation and harvesting. Once the
product is purchased, cooking can also add significant energy use and
energy expended in the act of shopping can be appreciable. For
this reason, more complete forms of analysis have been designed. Two
common approaches have been Ecological
Footprints and Life-cycle
Analysis
(links are to the web pages of other organizations). While these
methods are certainly more complete and are necessary for certain
applications, we felt food-miles were most appropriate in our case
because of their simplicity and direct linkage to the "localness" of a
product.
2) Actual energy use and pollution values are of course painful to
derive. We did not go out and ride the roads with all the store's
produce while attaching some fancy air sniffer to the truck's exhaust
pipe. Instead, we relied on an on-line road distance calculator (Mapquest)
and published estimates of the fuel use and carbon dioxide production
associated with different modes of transport (see references in Rich
Pirog's work).
We do not have the expertise to look at efficiencies in more detail
(e.g., we did not try to take into account potential differences in
efficiencies between local and long distance transporters).
Furthermore, we need to do more work identifying the shipping methods
for international cargo; whether something comes by air or sea makes
huge differences in the associated transport energies.
We can guarantee you that our fuel estimates are precisely wrong, we
can only hope that they are roughly right. Because they do not take
into account refrigeration during transport, the fact that most
transport does not take the most direct route but weaves amongst stops,
and many delivery vehicles spend part of their time travelling empty,
we believe that, if anything, we have underestimated actual energy
consumption and CO2
generation. Our most current estimates of gallons of gas equivalents
used per ton carried per 1000 miles travelled are 185.5, 26.7, 4.3
& 2.7 for airplane, truck, boat & train, respectively;
likewise, for pounds of CO2
generated per
ton carried per 1000 miles, we used 4554.0, 590.2, 94.4 & 51.3.
These values differ slightly, but probably not significantly, from
those illustrated in our poster. We used these values for our the
calculations appearing on our receipt.
3) Currently, our work has been limited to produce and dairy items.
While we could also calculate food miles for more processed foods, this
value seems somewhat meaningless given the energy involved in the
processing itself and the unknown distances that the ingredients have
already been transported by the time they reach the processing plant.
However, see estimates for Strawberry yoghurt out of the Leopold
Center.
4) Even with something as simple as fruits and vegetables, it is
sometimes not possible to know where an item comes from with any
precision. Certain distributors now mark their cartons with simply
"Product of the USA or Mexico". In our part of the country, such doubt
makes little impact on food miles considerations since "USA" almost
always means California. However, if organic fruit and vegetable
producer-distributors (e.g. UNFI) extend their national and
international reach, consumers will need to pressure for good source
accounting if they want to know where their food comes from.
Any
ideas or comments are
welcome. Please contact us if you have
questions or input. Enjoy!
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