Carbon Footprint of a Bowl of Cereal: Your Morning Fuel
Gotta love those inane little newspaper infographics. Even when the topic is serious or important, their chart-junkiness is just too cute to bear. You’d think newspaper editors would be onto this by now, what with Edward Tufte and The Onion out there. But no. This one was printed, USA-Today-style, on the bottom left hand corner of today’s Metro rag, in New York:
Metro cites “NewScientist” as its source, and indeed, in September 2008, New Scientist magazine ran an article titled What is your dinner doing to the climate? by Bijal Trivedi.
The article describes the painstaking mechanics behind the popular desire for easy-to-understand analogies. Here is an excerpt, my emphasis in bold:
The calculations can become “fiendishly complicated“, says Astrid Scholz, an ecological economist at Ecotrust, a think tank based in Portland, Oregon. Scholz led the development of a carbon calculator for the Bon Appétit Management Company Foundation, which developed a Low Carbon Diet for its 400 plus cafeterias in the US.
For example, to calculate the CO2eq impact of eating an industrially raised chicken breast, you would factor in the following. First, there’s the emissions from preparing the feed pellets. This would include the fertiliser, growing and processing the grain, and finally transforming it into bite-sized pellets that will feed the chicken while it sits in a hut with 250,000 other birds. Add to that the energy for heating the structure, the fuel for transporting the chicken to the slaughter facility, and the emissions from running the slaughtering facility and manufacturing the packaging.
Then there are emissions from transporting the animal to the wholesaler, the refrigeration costs of storing the meat, the trip to the retailer, and further refrigeration in the shop. Then you drive to the store, buy your chicken, drive home and cook it – all those emissions count too. Chicken is a relatively simple example, but the more stages involved in a food’s production, the harder it becomes to calculate its true CO2eq footprint.
Scholz found that until recently there had been no wide scale effort to calculate CO2eq for foods in the US. In Europe, however, there are fledgling programmes that have calculated CO2eq emissions for some foods, so she used these figures to create a carbon calculator that she says gives comparable figures for the US. “We took a Dutch chicken farm and plopped it in Texas and assumed that it worked in a similar way,” she explains.
She describes the resulting carbon calculator as “version 1.0 of a good idea”. It doesn’t give you the derivation of the figures, but it will tell you that 333 grams of CO2eq is emitted to make one hard-boiled egg. Compare that with a bowl of cereal with milk: 1224 grams of CO2eq – equivalent to driving a typical SUV 6 km.
The main culprit in the bowl isn’t the cereal, it’s the milk. That’s because the most emissions-intensive foods are red meat and dairy products. In general, red meat emits 2.5 times as much greenhouse gas as chicken or fish, since rearing cows and other livestock requires a lot of energy. It takes 2.3 kilograms of grain to make every kilo of chicken meat, 5.9 kg of grain for a kilo of pork, and 13 kg of grain plus 30 kg of forage for a kilo of beef. Worse still, they produce methane and their manure releases nitrous oxide.
However, Peter Tyedmers, an ecological economist at Dalhousie University in Nova Scotia, Canada, warns that such calculators should be taken with a pinch of salt. Tyedmers and his students provided much of the raw data for the calculator, and while he agrees it is a good idea in principle, he says the figures they came up with are specific not just to the precise types of foods they measured, but to every detail of where and how they were produced, so cannot be generalised. For example, regional differences in farming practices can make a big impact on the final figure, he says. Simply changing an animal’s feed can have a huge impact on its CO2eq footprint too. “It’s all very fluid,” says Tyedmers. “There’s a tremendous hunger for these sorts of numbers and this has created the assumption that any existing figures are robust. They’re not.”
Then, in October 2008, New Scientist ran the following correction:
• Our cover said that a bowl of cereal has the same carbon footprint as a 7-kilometre journey in a 4×4 (13 September). That was derived from emissions of the best-selling sports utility vehicle (SUV) in the UK; the 6 km figure inside (13 September, p 28) was for the average US SUV. Oops!
Well, excuse me. In terms of public awareness efforts, there’s seems to be this gulf between two extremes in approach, with these enviromental-impact-analogies. On the one hand you’ve got boring, extreme nitpicking, and on the other hand, you’ve got stupid-looking oversimplification. And the two approaches hurt each other’s credibility and efficacy.
Meanwhile, the original article included this very interesting and informative looking graphic:
But of course, it was the magazine’s cover that informed the look and feel of the infographic chosen by Metro: