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The Eco(Logical/Nomical) Impact of Food in the UK


People say that procrastination is a counter-productive thing. Who knows, maybe it is. To find out, I endeavoured to look up research on procrastination. Not exactly the most fascinating read, so I wandered off and ended up reading some of the blogs on thesimpledollar.com. One of the articles that peeked my interest was titled buying foods based on cost per calorie. A great idea, since we all have to eat and consume a certain number of calories each day, so why not do so as economically as possible? However, as is often the case, this was entirely based on US prices. And it completely overlooked the ecological cost of food.

The ecological cost takes into account how much stress we put on our one and only planet to produce any given type of food. If you don’t believe in global warming and the incredibly destructive impact humanity has on our planet, then you can probably skip this article and read something else (or maybe you can just assume this is an alternate fact and read on?). If you do believe that global warming is happening and that humans are causing in, like an overwhelming majority of climate researchers1, then taking the ecological cost into account is something that can help you guide your purchases and help save our planet.

The idea is rather straightforward. Instead of looking at the cost of the food in itself, we manipulate the cost to also reflect how much $CO_2$ is produced in producing that food. Vegetables that grow naturally in our own backyard will tend to have a rather low impact. Fruit that needs to be flown in from another continent has a high impact. The food that has the worst impact is meat from grazing species, such as beef and lamb. The problem is the huge amount of land they need to graze, the even bigger amount of land we need to grow food for these animals, and the tremendous amount of methane they produce – ok, you want it simple? cows fart a lot. One thing that complicates these calculations is that every continent is different. The UK, for example, is a great place to grow grains. But it is not the best place to grow Mediterranean vegetables such as most green leaf vegetables and tomatoes.

Luckily, the ecological impact of our food is something that is reasonably well-studied. By combining a couple of different (scientific!) sources and some meta-analyses I was able to gain a clear picture of the impact the food we buy in the UK has on our environment. For each food group, this gave me the number of grams of $CO_2$ that is exhausted (in production, processing, transportation, and waste) for every kcal of food. Similarly, it is rather straightforward to collect prices of different foods, figure out how many kcal we get from these foods, and come up with a number that tells us how costly each food is for every useful kcal. The question then becomes how we can marry these two measures; how do we combine the kost per kcal with the $CO_2$ exhausted for every kcal of that food?

To address this, I created a formula with a number of properties. First, the price of foods that have no ecological impact remains the same; second, the price of the worst offenders is quadrupled; and third, there is an exponential increase in how much the ecological impact boosts the price. Given that the grams of $CO_2$ for every kcal range from 0 to 14, this gave me the formula:

[ m = 1.15^{(x-5)}+(1-1.15^{-5}) ]

where the first half of the equation gets us the exponential formula, and the second half ensures that for $x=0$ (i.e. an item without an ecological impact) we obtain $m=1$ (the price is multiplied by 1, i.e. it remains the same).

The formula looks as follows when plotted:

magnifier formula plot
The formula maps the CO2 output (on the x axis) to a magnifier (on the y axis).

As briefly mentioned before, the output $m$ of this formula is a multiplier that will be applied to the original price per kcal to give us the eco impact measure. For example, if the price we obtain for 100 kcal of a product is $1.2$, and the multiplier is $2.5$, then the eco impact of the product is $1.2 \times 2.5 = 3$. This eco impact measure not only reflects the immediate (financial) cost, but also the (ecological) cost of producing the food. The eco impact measure can simply be read as a value in £. Indeed, it reflects both the immediate and ecological cost in one value. All that is left is to collect all the data (in most cases supermarket-brand products were chosen), put it through the formula, get a nice infographic ready, and we’re all done. 2

magnifier formula plot

You can find the high-resolution, finger licking gorgeous infographic here. A few things are exactly as you would expect them to be. (Most) vegetables are good. Locally grown fruit is good. Fruit that is transported slowly and ripens here is good. Beef and lamb are bad. Fish is expensive. It gets interesting though when you look at the things that stand out. For example, green salads and tomatoes are a pretty poor choice (for a vegetable). The reason is that they either have to be imported, or be grown in expensive greenhouses. When it comes to meat, pork is a much better choice than beef or lamb. Once again, a bit of reasoning is all it takes to work this one out. Pigs are omnivores, so they eat, well, everything! This ensures that they don’t leave a massive ecological impact due to the land needed to grow their food. The final one worth pointing out is the last one on the last list. The beans with the lowest eco impact are the famously popular beans in tomato sauce. Talk about a culturally biased infographic!

I hope this infographic will help you guide the food choices you make. For example, to get your daily 2,200 kcal you could spend 77 on beef sirloin or 0.66 on rice. Of course, no one wants to just eat beef or just eat rice. Yet the choices you make will have a profound impact on both your wallet and the planet. Personally, I will try hard to only chose those products with an eco impact of 0.5 or less. I will also grow those tomatoes and greens myself in the house as this is already heated anyway to accomodate its inhabitants. Yet I’m not here to tell you what you should do, so do make your own conscious choices and chose whichever level or budget you feel comfortable with. And do feel free to share the infographic with whomever would be interested in it!

As a rather nice side-effect of this endeavour, I also answered my original question. No, procrastination is not counter-productive. You’re welcome.

  1. Unlike in politics – where 52/48 is considered an “overwhelming” majority – the criteria in science are somewhat more stringent. When it comes to climate change, 97% of climate researchers believe that humans are the dominant cause of global warming since the 1950s. 

  2. All prices were collected on the 4th February 2017 from the leading supermarket in the UK. Whenever possible, the supermarket-brand products were chosen (not the Everyday Value series, nor the Finest series). The only branded product in this list are the cornflakes. While the infographic is mostly based on the original infographic that only listed prices per kcal, there is one marked change; fruits and vegetables are prices for half cups rather than full cups. This seems to offer a fairer and more direct comparison with the other bar charts. As a bonus, every half a cup you eat counts as one of your daily 5 portions of fruit and vegetables.