Is walking more polluting than driving?

On August 4, The Times quoted UK parliamentary candidate Chris Goodall who claims that walking 3 miles (4.8 km) adds four times more CO2 to the atmosphere than driving the distance in "a typical UK car". The calculating behind this statement assumes that a person has to eat about 100g of beef to power the walk, and beef production is polluting. The question that jumps to mind is, what about the car's fuel? Where did that come from?

Here are another few questions that might balance the statement a little (I don't know the answers to them, so maybe they don't add any balance whatsoever. And although thinking requires energy and thus adds to my emission of CO2 today, I find them both amusing and worthwhile to ask):

• Who lives solely on beef? I don't question that meat production requires a lot of energy--I recall having heard already in secondary school (about 20 years ago) that producing one kilo of meat consumes 10 kilos of fodder. The problem is that I can't think of anyone who only eats meat--perhaps with the exception of people who follows the Atkins diet...
• How much CO2 does the walking person emit directly into the atmosphere, not considering that she (or he) have to eat in order to walk? This is probably an over-simplified way of ruling out the cost of producing and transporting petrol, but nevertheless an interesting way of putting things into perspective...
• Or what if we start off from the beginning, and compare 1) how much energy and emission it takes to raise a human being ("a typical UK citizen") with 2) the energy and emission it takes to produce "a typical UK car"-- including putting shoes and clothes on the human being, and mining and transporting metals for the car, etc...?
• And finally: How much energy and emission does it take to bring the person back to nature (the concept of "earth to earth, ashes to ashes, dust to dust") compared to decomposing the car (no similar expression for the car, as nobody have yet witnessed a car become earth, ashes or dust--without help from mind-bending amounts of energy).

Of course, nobody can give definite answers to any of the questions above, with perhaps the last being the exception. However, it wouldn't hurt if journalists spent two extra calories to ask questions that might help people (like me) to better understand what is actually going on.

Or maybe not, as it would require extra energy, contributing to even more emissions of CO2...?

Update:
Even more alarming than the journalists lack of questions is the teeny-weeny white-paper beef.pdf that is supposed to support Mr. Goodall's statement--it clearly says that the question about where the car's fuel comes from is in fact not at all taken into consideration...

But it gets even better, as the document actually says that "we have gradually become aware of the huge amounts of grain needed to feed our animals". I don't know the definition of "gradually", but someone actually thought this out and delivered the message to me and a lot of other kids some twenty years ago...

The one good point in the document is that sharing a car is still good, although with an incredible argument: "if there are two of you, and you share the car, then walking would be eight times as bad for the climate". In other words, although we've known it all the time, it is good to share a car-ride, but now because it would be twice as bad (for the climate) to walk! Go figure.

All these negative comments aside, there is in fact one underlying positive message in Mr. Goodall's statements: Modern food production is very energy-consuming, with the brute example being prefabricated food conserved in refrigerators. So the moral is: grown your own food, or buy it fresh from your neighbour.

Bon appétit!