When it comes to saving the environment, things are often not as simple as they seem at first blush.
Take, for instance, the debate about paper bags vs. plastic bags. For a number of years, anyone who opted for plastic bags at the grocery store risked the scorn of environmentalists. Now, it seems that the consensus has swung the other direction — once a more careful cost accounting is done.
The same sort of uncertainty hangs over the choice of disposable diapers vs. cloth diapers.
At least some choices are beyond reproach environmentally. It is clearly better for the environment to walk to the corner store rather than to drive there. Right?
Now even this seemingly obvious conclusion is being called into question by Chris Goodall via John Tierney’s blog. And Chris Goodall is no right-wing nut; he is an environmentalist and author of the book How to Live a Low-Carbon Life.
Tierney writes:
If you walk 1.5 miles, Mr. Goodall calculates, and replace those calories by drinking about a cup of milk, the greenhouse emissions connected with that milk (like methane from the dairy farm and carbon dioxide from the delivery truck) are just about equal to the emissions from a typical car making the same trip. And if there were two of you making the trip, then the car would definitely be the more planet-friendly way to go.
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Maybe so, but it also takes energy to prospect for oil, drill it out of the earth, transport it, refine it, distribute it to the fuel station, and to keep the gas station’s electricity on while you pump the gas. Also there is wear & tear on the car from this short trip, contributing ever so slightly to an eventual repair. All of those things require energy as well and should be accounted for in the total emissions produced by that short trip.
It also matters whether the car is already warm or if it’s been sitting out for a while. Catalytic converters only work well when the exhaust has warmed them up to a certain temperature. If you cold-start a car and drive just 1.5 miles, the emissions are much higher than tacking 1.5 miles onto your trip home from the office.
To be precise, you also need to account for the wear & tear on your shoes and clothes when walking to the store vs. driving. It matters if it’s a sunny dry day, or if you have to walk through slush, possibly ruining your shoes, and so you then have a reason to buy new shoes, which have their own environmental costs to add up as well. This cost is de minimis for a short trip, but my point is that the “big picture” look gets very complicated when you factor in everything.
The glaring fault in the logic is assuming that you will “replace the calories” burned from walking to the store. If you maintain the exact same lifestyle and food consumption that you would normally, and choose to walk instead of drive, then walking is undoubtedly the better option.
Also, he’s equating the entire process of getting the milk from the cow to the consumer with just the drive to the store. If he was trying to be intellectually honest, he would have to factor in the process of drilling for, refining, and then transporting the gas to the gas station before you put it in your car. That doesn’t even factor in the production of the car itself.
There are a few logical fallacies with this analysis. I can think of two off the top of my head…
The most obvious one is the assumption that that walker will need to “replace those calories”. The vast majority of north americans currently consume more calories than are required by their activities – that’s why we’re getting fat. Marginal analyses of physical activity by people in developed nations should be based on the assumption that the decision about how many calories to consume is independent of the physical activity undertaken – because empirically this is the case.
A second fallacy is that this analysis looks only at the carbon impact rather than all of the other externalities (non-carbon pollution, congestion, impacts on neighbourhoods etc.) which uniformly are negative for car use and positive for walking.
I’ve been awaiting the following argument for quite some time:
Exercise is bad for the environment – playing recreational sports, going for hikes in the mountains, riding a bike on a warm sunny day – all bad for the environment. Whenever we partake in unnecessary physical activity of any sort, we are burning calories. Calories which must be replaced if we are to maintain the same body mass.
There is no such thing as a free lunch: If you burn extra calories through exercise, then you must replace those calories through increased food intake. The only way around this is if your exercise causes you to permanently lose weight. Anyone who is maintaining a constant body mass whilst engaging in unnecessary exercise must replace that spent energy with increased caloric intake.
Maybe in the future going on a nice bike ride will be socially equivalent to driving a Hummer.
How silly.
What if I replaced the calories with a hamburger? Then I would be eliminating the evil methane producing cow.
Why are people spending valuable time worrying about this stuff?
Chris Goodall rebuts some of the problems raised in the comments section here.
http://tierneylab.blogs.nytimes.com/2008/02/25/how-virtuous-is-ed-begley-jr/#comment-99762
“This cost is de minimis for a short trip, but my point is that the “big picture” look gets very complicated when you factor in everything.” – Posted by Scott.
And the majority of times the actual solution to that complicated big picture is counter-intuitive. So many issues are perceived in contradiction that the real solution rejected as being paradox. From error to error we stumble on our way to the future, if not to progress.
That’s it! From now on I’m drinking only gasoline!