Is it steak?
An average individual is making hundreds of consumption decisions a day - a 2006 Cornell study found that study respondents made an average of 221 daily decisions on what to eat and drink alone. All those decisions relate to a judgements about price, quality, calories, presentation, and potentially, environmental impact.
To help consumers make more conscious decisions about the impact of their purchases thus means answering two questions:
- Which are the purchase decisions with highest environmental impact within my lifestyle?
- For each of those decisions, which (if any) do more environmentally friendly alternatives exist?
Not all emissions are made equal. Large purchases like furniture, appliances or a new car can have very high-emissions but are spread over many years to come. Flights or travels, on the other hand, are consumed “on the spot”. Yet other items, like food, drinks or, cosmetics are small but frequently recurring and rack up over time.
To determine how relevant a consumption habit is, we should thus not only find not how much emissions it causes at the time of purchase - but how much is it does the course of a whole year.
For example, at 8.3kg of CO2 buying a new Apple Watch might have the same emissions as a single car trip of about 20 kilometers. But if the car trip constitutes a daily commute, whereas the watch is used for years to come, the former is much more important to account for.
But how do you know either of the two are really relevant in the first place? In other words, can we determine some kind of cut-off that tells us which emissions are relevant to account for and which are not.
Food and Drinks
Regarding food choices, the primary environmental concern on many people’s mind is either “is it local?” or “is it organic?”, with the belief being that the lack of chemical treatment and shorter transportation paths would account for much of the environmental damage done by food production.
On first glance, this makes a lot of sense - with so much emphasis placed on the emissions from shipping and air travel, an avocado from Peru can’t possibly be better for the environment than a beef steak from the farmer next door, can it?
Let’s look at the numbers, we see a different picture. Largely due to methane emissions, one kilogram of beef comes in at between 20 and 60 kg of CO2eq emissions - depending on whether it comes from a dairy herd. In comparison, avocados emit a meager 3kg on average, less than 10 percent of which come from shipping.
In the extremely unlikely case that it was shipped via air - only 0.16% of food is transported that way - it would still only come in at only 10kg per kg of product, or about half of the lowest estimate for beef.
The more one looks at this chart, the more striking it becomes that to account for the vast majority of the variability on food emissions, it is enough to track the consumption of a handful of items, first among which beef, lamb, coffee, cheese, and chocolate.
This leads us to two interesting observations.
- It is crucial to be specific about individual products rather than generalizing about categories as such. A heavily dairy-based vegetarian diet might be, for example, more emitting than a chicken-heavy non-vegetarian one.
- At an average carbon footprint of about 10kg, a steak (250g) can be more emitting than a weekly commute. In fact - it is more emitting than an entire Eurostar round trip from Paris to London - for two people.
With this in mind, we realized that “is it steak” is a pretty good measurement - not just for grocery emissions, but for with any kind of purchase decision.
Transportation
Below is a chart of the carbon impact of various transportation methods per kilometer, based on data from the United Kingdom. Unsurprisingly, the Eurostar stands out as the by far most efficient option, coming in at only 4 grams of CO2 per kilometer travelled - or about 98% less than a comparable flight.
At the average TGV emission factor, one could travel 2857 kilometers until reaching the emissions of a single steak - or about the distance from Paris to Istanbul.
But how does this compare against other options?
In the London Tube, a person would have to travel almost 400 kilometers to reach 10kg of emissions - or a little over one kilometer a day - in a local bus, it would be only 120 kilometers.
In Paris, the contrast is even more stark with 2631 kilometers by metro vs 105 by bus - based on 2019 data before the wide-scale introduction of electric buses. It is likely that this number has doubled since.
In general, for buses and cars, the numbers can vary vastly, depending on the engine type and the number of passengers. Whereas for a single passenger in a petrol car, we only get ~60 kilometers for 10kg of emissions, the range could go as high as 800 kilometers for a modern electric car with four passengers.
Flights, for well known to be among the least climate-friendly ways of transportation. This is true for several reasons which we will explain in detail in an upcoming article - least among them is the lack of efficiency for air travel. At 50km for a 10kg of emissions, a standard flight is no more carbon intensive than a solo car trip - however is it likely to cover much longer distances.
Charting various available modes of transport shows us that railways easily eclipse all other available modes of transportation - including walking, which (assuming that burned calories will be replaced) turns out to be among the least efficient.
Outliers for cars (electric cars with multiple passengers) and planes (using commercially available biofuels) highlight the opportunities of technological progress and are often held back by a mix of higher prices and lack of affordability to a wider number of consumers.
Housing
“Turn off the lights when you leave the house” is one of the first environmental gestures many people learned as a child - but just how does it really help?
A standard LED lightbulb consumes between 4 and 8 Watts, making for between 35kWh and 70 kWh in a year - or about 1.5kg to 3kg of emissions over that time, at a price of 10-20 Euros. In other words - leaving the light on doesn’t come at as high a price anymore, neither for us, nor for the climate. It has the equivalent impact of eating one less steak - every five years.
<< data-preserve-html-node="true" chart on average consumption of different appliances over a year >>
For comparison, a typical 2000W electric heater can burn through that in a single night. In a typical year, a French electrically-heated household consumes a total of 4 312 kWh of electricity for heating. That’s over one metric ton of emissions - or as much as a long-distance flight.
Fashion
Lastly let’s have a look at another much-discussed industry
Below you will find two common fashion items from the French brand “Maje” - both come at a premium price point 235€ and 355€ respectively. What would you guess their footprint to be? Both as a one-off purchase, or annually, spread over a course of four years.
Whereas the jeans emit 7.8 kg of CO2eq at the time of purchase, the cashmere sweater emits a whopping 218.7 kg - or about as much as a short-haul flight (e.g. Paris-London).
Annualized over four years, the emissions come in at 55kg of CO2eq, that’s not just “steak” but more than buying a new iPhone each year (48kg of CO2eq for the iPhone 16e).
For another example, let’s have a look at the three earrings below, showing similar earrings in three metal options: silver, gold, and platinum - how big would the difference in emissions be?
While the silver earring comes in at only 0.34 kg of CO2eq at purchase, gold and platinum lie at 31kg and 90kg respectively. For the platinum version, when used over a course of 50 years, that’s still 2kg a year - or about as much as a Paris-Marseille train ride.
Cases like these show just how vastly different emissions for seemingly similar purchases can be. But beyond these illustrations, is there a way to find out before purchasing a product?
Conclusion
To answer this question, we created Colibri - a first of a we kind personal carbon tracker, built on the largest publicly accessible product catalogue for carbon emissions factor which we compiled over the course of the past 18 months.
Within the Colibri App, you can look for emission factors of thousands of real-world products, from the latest iPhone over a pair of new jeans to a serving of your favorite meal.
Download our app now and become a beta tester of Colibri. On the Colibri app, you not just browse emissions but easily compare items before purchase and monitor your personal carbon footprint evolution over time for a more climate-friendly lifestyle.