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August 5, 2007
More fun with carbon footprints
This earlier post generated some comments. Let's see what happens this time. I tip my hat to Marginal Revolution for the link. (TimesOnline UK)
Walking does more than driving to cause global warming, a leading environmentalist has calculated.
Food production is now so energy-intensive that more carbon is emitted providing a person with enough calories to walk to the shops than a car would emit over the same distance. The climate could benefit if people avoided exercise, ate less and became couch potatoes. Provided, of course, they remembered to switch off the TV rather than leaving it on standby.
The sums were done by Chris Goodall, campaigning author of How to Live a Low-Carbon Life, based on the greenhouse gases created by intensive beef production. “Driving a typical UK car for 3 miles [4.8km] adds about 0.9 kg [2lb] of CO2 to the atmosphere,” he said, a calculation based on the Government’s official fuel emission figures. “If you walked instead, it would use about 180 calories. You’d need about 100g of beef to replace those calories, resulting in 3.6kg of emissions, or four times as much as driving.
...
Catching a diesel train is now twice as polluting as travelling by car for an average family, the Rail Safety and Standards Board admitted recently. Paper bags are worse for the environment than plastic because of the extra energy needed to manufacture and transport them, the Government says.
Fresh research published in New Scientist last month suggested that 1kg of meat cost the Earth 36kg in global warming gases. The figure was based on Japanese methods of industrial beef production but Mr Goodall says that farming techniques are similar throughout the West.
What if, instead of beef, the walker drank a glass of milk? The average person would need to drink 420ml – three quarters of a pint – to recover the calories used in the walk. Modern dairy farming emits the equivalent of 1.2kg of CO2 to produce the milk, still more pollution than the car journey.
So I guess we are supposed to sit really still and not eat meat or drink milk.
Isn't this just an extension of my previous post? Rail is more fuel efficient than automobile. Automobiles are apparently more fuel efficient than cellular respiration.
Oops, but did he say that "catching a diesel train is now twice as polluting as travelling by car for an average family"? Does that shoot a hole in my theory? Read to the end of the article...
Diesel trains in rural Britain are more polluting than 4x4 vehicles. Douglas Alexander, when Transport Secretary, said: “If ten or fewer people travel in a Sprinter [train], it would be less environmentally damaging to give them each a Land Rover Freelander and tell them to drive”
Nope. It sounds like my theory is still ok as long as more than 10 people are on the train. Yes, volume matters. You want to be able to spread those carbon emissions over as many people as possible to minimize the average carbon footprint. For what it's worth, I live in a rural area and occasionally take the train. I would estimate that the number of riders on every trip that I've taken probably peaked at around 100 (sometimes quite a bit more). I don't know how our trains compare with Britain's for fuel efficiency, but I like to think that I'm helping the environment.
Mr. Goodall continues:
“We have industrialised our food production. We use an enormous amount of processed food, like ready meals, compared to most countries. Three quarters of supermarkets’ energy is to refrigerate and freeze food prepared elsewhere.
...
The ideal diet would consist of cereals and pulses. “This is a route which virtually nobody, apart from a vegan, is going to follow,” Mr Goodall said. But there are other ways to reduce the carbon footprint. “Don’t buy anything from the supermarket,” Mr Goodall said, “or anything that’s travelled too far.”
I think there is something very important to remember here, and it applies to my previous post on the subject as well. Taxing carbon is not the same as taxing the food or the mechanism that transports the food. If the point is to reduce carbon usage, then tax carbon. Let the market adjust to the new energy prices and continue to bring the food to market in the least costly way. If it's still cheaper to bring large volumes of food long distances than small volumes short distances, then a carbon tax does not equate to a "buy locally" campaign. A carbon tax probably isn't going to mean the end of supermarkets either. In fact, if Mr. Goodall is right, it's probably better for the planet to load up the minivan at the supermarket than to carry the same amount of food (which might take you several trips if you're walking) from the corner grocer.
If you're going to tax carbon, then tax carbon. Don't make judgments about which uses of carbon are better. Tax carbon and let the market sort out which uses have the most social value. Don't let carbon be a back door for protectionist or other agendas. If foreign fruit from the supermarket is still a good buy for the consumer (relative to the alternatives) even with a carbon tax, then so be it.
UPDATE: On a similar note, here's a New York Times article on recycling plastic bags.
“It was illustrated vividly at a hearing where a stack of 500 paper bags was two feet high and heavy and 500 plastic bags was two inches high,” Mr. Christman said. “It requires seven times as many trucks to move an equivalent number of paper bags. The environmental profile of plastic is better than alternatives. It is an environmentally responsible choice to reuse them and recycle them.”
Posted by William Polley at August 5, 2007 10:36 PM
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Comments
I would distinguish carbon producing fossil fuels from carbon neutral biofuels though.
Posted by: Lord at August 6, 2007 2:53 PM
Sure. A carbon tax would encourage that sort of substitution across the spectrum which would be beneficial. That would be a long run shift though, and the full general equilibrium effects would be more complicated to work out.
Posted by: William Polley at August 6, 2007 3:07 PM
Fun is fun but lets just color me skeptical here:
"Food production is now so energy-intensive that more carbon is emitted providing a person with enough calories to walk to the shops than a car would emit over the same distance."
Now if I could just send my car to the store without me then maybe this works. But you continue to burn calories even while seated behind a steering wheel. Does the net caloric burn of walking over resting really emit more carbon than the combination of resting and driving? You would hate to think this guy just left the driver out of the calculation just to make a cheap point. Which I guess would make me a hater.
Posted by: Bruce Webb at August 10, 2007 1:48 PM
He used 3 miles as his distance. Say that takes 10 minutes to drive (that matches my time and distance to the supermarket almost exactly). How many calories do you burn sitting still for 10 minutes? I used this calculator
http://exercise.about.com/cs/fitnesstools/l/blcalorieburn.htm
to come up with about 15 calories for watching TV for 10 minutes for a 180 pound person.
So even if he did make that mistake (and the article doesn't give us enough info to say for sure), it makes less than a 10 percent difference in the number of calories, and so doesn't change the result.
There are probably better grounds on which to criticize the study. He assumed the calories were replaced by eating beef or drinking milk which are sort of worst case scenarios carbon-wise.
There is certainly a grain of truth in what he claims, but the danger here--as is the danger so often with things like this--is in the extrapolation. Ultimately he comes to the conclusion that you shouldn't buy anything from the supermarket or anything that's traveled too far. Honestly, and I am not trying to make a cheap point here, I'm serious... how different is that in concept from Mrs. Edwards' tangerine example--which also has a grain of truth but doesn't scale up very well?
Posted by: William Polley at August 10, 2007 2:59 PM
I would want to know how many more calories pedestrians actually eat vs drivers -- they aren't necessarily increasing caloric intake to maintain middle-age spread parity with SUV drivers.
The New Scientist article referenced in the Times story --
http://environment.newscientist.com/channel/earth/
mg19526134.500-meat-is-murder-on-the-environment.html
-- references research to the effect that organic grass-fed beef involves considerably less GHG emission vs. 'factory' methods. That's presumably because the grass-fed cows are less flatulent, as it's their, er, tailpipe emissions that are responsible for most of the 3.6 kg of GHG. That itself is significant, because the carbon in that methane wasn't sequestered hundreds of millions of years ago. The question, in effect, is whether more human-powered transportation implies a bigger (aggregate) herd of cows.
I also wonder what, in this view, one would make of someone idling their SUV at a McDonald's drive-through while waiting for delivery of 114g (or more) of beef.
Posted by: Tom Bozzo at August 10, 2007 4:07 PM
There are two issues. One is the efficiency of the engine. The other is the efficiency of the process by which we get the fuel. The efficiency of the engine is the easy part. Science can tell us everything we need to know about the internal combustion engine and the way the body converts food into energy so we can make those comparisons. That's the easy part.
Tracing the efficiency of the production of fuel is harder because there are so many processes in use. If the goal is to reduce carbon emissions, then tax carbon emissions. (And get as detailed as you can on significant sources of emissions--even cow flatulence--and tax that appropriately.) Then the market should reward the more efficient processes. That is better than guessing which processes to ban or limit.
Posted by: William Polley at August 10, 2007 5:16 PM