Monday, December 21, 2009

That exercise carbon-footprint study

Remember that study? Maybe, like me, you heard it on the radio while driving home from work a couple of years ago (yes, I sometimes drive to work; usually about once every two weeks). It reached the conclusion that walking to do our shopping actually carries a larger carbon footprint than driving a car to shop does, because of the extra calories burned by walking and the extra carbon emissions the extra food needed to replace them requires. So, walking makes us tired, and destroys the environment in the bargain? Lots of people want to believe that! The study (if you can call something that superficial a study) made the mainstream news by virtue of being so outrageous... and no doubt pleasing the global-warming doubters.

Pretty funny, huh! Here we ride along, all happy about our contribution to the environment, when in fact we may be the worst destroyers of it? Well, the study (by a British Green Party parliamentary candidate, ironically enough) didn't mention our more-efficient biking, but still.

The basic concept was that the extra food we have to eat for fuel to walk (or perhaps ride our bikes) requires more energy to produce, transport and cook than car-driving to the store (and thus eating less) does. Think of the farmer's tractors, chemical fertilizers, food transportation, refrigerators, stores and ovens involved to produce our extra food: the more we eat, the larger our carbon footprint. What's funny is that it seemed very plausible to me! Well, on the surface of it anyway.

But, like so many studies, this one was pretty flawed. The largest error was in the assumption that the extra calories we'd need to consume all came from British beef. Uhhhh... I thought the extra calories came from doughnuts! Real experts were able to easily reach real conclusions and debunked the study.

The fact is that some methods of transportation are more efficient than others, and car-driving isn't one of them. A UC Berkeley study, by Teresa Zhang, concluded that car driving accounts for a majority of a person's carbon footprint over a lifetime. It's important to consider all of the energy required to build, maintain and support cars; millions of people work in auto-related industries and their footprints could arguably be attributed to autos, in part at least. Think of all of those big roads and bridges too, and the carbon footprint they have. Sidewalks and bike paths require far less energy to build and maintain. That study neglected those details too.

So that just goes to show that studies are only as good as the people who make them. If I stopped riding and drove to work instead, I'd burn more gas, and become fat! But both of these studies help raise awareness, which is good. It certainly made me think!

So one thing I've done differently over the years is to try to buy local foods as much as possible. Local foods require less fuel for transportation (and taste better too because they can be picked closer to their ripe state). And I have always been careful not to waste food, unlike your average U.S. citizen (being a child of Great Depression-era parents who also grew up in Occupied Europe during WWII gets some credit) In fact, I'm kind of a Hoover. I always grab the leftovers nobody else wants, eat the food that's past it's expiration date (slightly expired food is usually perfectly safe, maybe just a bit less fresh, according to the experts). A human garbage disposal in short, not a beef-eating gourmet.

And I now use a basic rule of thumb: the more something costs, the bigger its carbon footprint. It makes a lot of sense, up to a point. Higher costs usually are related to the labor, transport and storage of goods: all carry a carbon footprint price tag. Think of a Mercedes vs. a Hyundai. The Mercedes costs more because the R&D time to design it is longer, the labor costs higher, there's a lower economy of scale due to lower production volume, etc. And people in developed countries usually have a larger carbon footprint already (higher labor costs reflect that). The same concept can apply to things like out of season produce, expensive clothes etc.

Save money, save the planet. Good thing I'm a cheap-skate too.

See, even flawed studies can help us make positive changes!

2 comments:

Anne said...

interesting post...

I read somewhere that buying local was actually less fuel efficient because typically, smaller, less efficient means of transportation were used to get the food to market. I wasn't sure what to make of it. But I assume that if the majority of people ate locally produced food (when possible), transporting it would become a more efficient process.

I can't remember where I heard that discussion; probably it was NPR or similar. I would be interested in a flushed out study of the matter...

-Anne

Dennis the Mennis said...

Very possible! Usually there's a complicated relationship between these factors. My Masters-in-Math brother once read an article dissecting how sheetrock manufacturers decide where to build factories. It was a complex math problem to factor the raw material locations in with the transportation costs and the customers' locations. No doubt there's a similar "sweet spot" with regards to buying food. Argentina may be too far, but maybe the farmer in Prunedale who drives his '64 pickup to the farmer's market is too close.