RE: [asa] CO2 in Food Production...

From: Jon Tandy <>
Date: Mon Dec 07 2009 - 11:12:15 EST

I think this response, while interesting, misses the point. The fallacious
argument on food consumption, at least a more advanced version of it,
doesn't just compare the energy consumed by eating and walking vs. driving.
The question below talks about the energy consumed in "food production", not
just the amount of energy in the food being consumed. And yes I do consider
it a fallacy, a typical urban legend unless it's backed up with hard data
about the amount of CO2 released in growing, producing, selling and
distributing a 2000 calorie meal to my plate, as compared with the amount of
CO2 released in driving my car to work. In my case, I would have to walk 70
miles round trip, so I might need quite a bit more than 2000 calories (not
to mention needing an extra 18 hours per day).

Oh, another potential fallacy in the statement that would need to be backed
up by data: it would need to take into account the differential amount of
food consumed by walking, not just the 2000 total calories consumed per day
but only the difference in food consumed as a result of walking vs. driving.
It might not be negligible, but it might be. Then there are the health
benefits that could result, including lower expenses and therefore energy
consumption in the health care system, etc. It's one of those complex
calculations that I can't image the (presumably) "urban legend" has fully

Jon Tandy

-----Original Message-----
From: [] On
Behalf Of Merv Bitikofer
Sent: Monday, December 07, 2009 7:11 AM
To: John Walley; asa
Subject: Re: [asa] CO2 in Food Production...

The trivia you mention below is a fallacy. From David McKay's "Sustainable
Energy - Without All the Hot Air"
(Book is available on-line)

Here is an excerpt from his "Mythconceptions" section on p. 79:

"I heard that the energy footprint of food is so big that "it's better to

Whether this is true depends on your diet. It's certainly possible to find
food whose fossil-fuel energy footprint is bigger than the energy delivered
to the human. A bag of crisps, for example, has an embodied energy of
1.4 kWh of fossil fuel per kWh of chemical energy eaten. The embodied energy
of meat is higher. According to a study from the University of Exeter, the
typical diet has an embodied energy of roughly 6 kWh per kWh eaten. To
figure out whether driving a car or walking uses less energy, we need to
know the transport efficiency of each mode. For the typical car of Chapter
3, the energy cost was 80 kWh per 100 km. Walking uses a net energy of 3.6
kWh per 100 km - 22 times less. So if you live entirely on food whose
footprint is greater than 22 kWh per kWh then, yes, the energy cost of
getting you from A to B in a fossil-fuel-powered vehicle is less than if you
go under your own steam. But if you have a typical diet (6 kWh per
kWh) then "it's better to drive than to walk" is a myth. Walking uses one
quarter as much energy.

<end of excerpt>

... and the "typical cars" he refers to are probably including European cars
which are better on average then U.S. cars. Also, bicycling (I know this
from personal experience) involves even less energy expenditure than walking
or running. But of course, this is just the activity itself and doesn't take
into account the carbon footprint of building the needed bicycle. But if we
are to take production footprints into account then the car falls even more
dismally behind. So bicycling probably has cars beat no matter how many
hamburgers & cheese crisps you eat. Beating the auto transport industry's
carbon footprint is like taking candy from babies. We would have to
seriously try in order to be any worse. Shoot, --even loaded 747 jetliners
can do it if the alternative was to put each driver into his own S.U.V.
(which would nearly be typical here in the U.S.)


John Walley wrote:
> Here is an interesting tid bit of trivia I found while researching this.
Does anyone know if this has any basis to it or not?
> John
> Here's a fun fact for you: If you live within walking distance of work,
which do you think would put more CO2 into the atmosphere, driving to work,
or walking to work? Contrary to what most would expect, the correct answer
is walking to work! The food production that would be necessary to replace
the calories that you would burn would put three times as much CO2 into the
atmosphere than driving your car the same distance! Thus, if you buy into
this global warming stuff, you better not exercise, because you are "causing
global warming!!"
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Received on Mon Dec 7 11:13:19 2009

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