Because roughly one-third of all greenhouse gas emissions that cause climate change come from food production, adopting a climatarian diet is one of individuals’ most powerful tools to help mitigate climate change.  At Cherwell Collective, we believe that one technique that restaurants, cafes, and canteens can use to help consumers adopt a climatarian diet and choose meals with a lower carbon footprint is to price those meals using their Carbon Cost, or a Carbon Costed menu.

Carbon Cost is a metric that transparently shows the car miles equivalent greenhouse gas emissions associated with each menu item. Carbon Cost pricing sets menu prices based on the Carbon Cost of each item, such as 1£ per car mile of emissions.

We recently conducted a Carbon Costed menu pricing trial that demonstrates how using this tool successfully encourages consumers to make choices more sustainable food choices

Carbon Cost Pricing Promotes Climatarian Choices

Cherwell Collective runs a yearly Carbon Cost campaign supporting food businesses in using this pricing to increase transparency for consumers.  Year-round, at our Climatarian Kitchen, we Carbon Cost our menus–even those that are “pay what you can”. If our cafe offers a serving of rice and beans, we set a price of £3, because that meal represents 3 car miles worth of emissions.  Meanwhile, for a cheeseburger, we suggest paying £10, because making a cheeseburger produces the same emissions as driving about 10 car miles.

In these annual campaigns, we have observed that Carbon Cost pricing can change behavioral patterns when ordering food.  When the environmental consequences of a dish are made apparent in its pricing, people tend to select more climatarian dishes.

However, when cafes typically participate in our Carbon Cost campaigns, these are not controlled experiments that compare the same menu without Carbon Cost with the same menu using Carbon Cost pricing.  The menus differ, and the observed effects could be related to other variables like the particular taste of diners. We could learn more through a more controlled experiment in which exact menus were replicated with and without Carbon Cost pricing.

Experiment at Lady Margaret Hall Shows Effect of Carbon Costed Menus

For our annual Carbon Cost of Food Week in 2024, Cherwell Collective partnered with Lady Margaret Hall.  This year we wanted to try a more controlled experiment to compare the same menu in the same place with the same audience, with Carbon Cost and without.  This will help us understand the scale of the impact of this pricing.  Our partners at Lady Margaret Hall, one of the University of Oxford Colleges, have a 4 week menu they run twice during each 8-week term. This year they used Carbon Cost pricing on their menu during our campaign week, and we compared that to ordering patterns for the exact same menu at another time in the 8-week term using normal pricing. 

Lady Margaret Hall serves only plant-based menus on Wednesdays and very limited options on Saturdays, so we excluded those days of the week from our comparison.  Overall we found that during the week that used Carbon Cost pricing, relative to the week using regular pricing, sales of plant-based meals, which have a significantly lower footprint of greenhouse gas emissions, jumped by 20%, while meals that included meat saw a 10% decline.

To make Carbon Costing visually intelligible, we designed a simple odometer graphic for menu items. Please note that individual dish prices differed each day, and below we discuss average patterns across dish types: fully plant-based (vegan), and dishes that contain animal products including both vegetarian (contains dairy and eggs) and meat-based dishes.

Example of a Carbon Costed Menu from Lady Margaret Hall

Screenshot

Carbon Costed Menus Saw More Plant-Based Meals Ordered

Lady Margaret Hall served 1,048 total dishes during Carbon Cost of Food Week in February 2024. The college then ran the exact same menu of items during a week in March using their regular pricing scheme where they served 985 dishes. We compared ordering patterns to evaluate the impact of the Carbon Cost pricing.

During the Carbon Cost of Food Week, meal choices that include meat-based animal products, such as buttermilk chicken, BBQ glazed salmon, and pasta carbonara, saw lower quantities ordered than the follow-up week of ordinary pricing. Meanwhile, Carbon Cost prices helped boost the sales of plant-based (vegan) meal items such as a vegetable-based stir fry and a bean chili compared to the week of normal prices. 

Vegetarian Meals Can Have a High Carbon Cost Too

We also looked at ordering patterns for “other dishes”  offered, those vegetarian but which contain animal products such as eggs or dairy, such as such as mushroom ravioli in a cheese sauce or spinach omelettes with cheddar cheese. These dishes typically have a Carbon Cost that falls in between the meat and plant based mains but we also saw an increase in demand for these types of dishes off the Carbon Cost menus relative to regular pricing.

Consumers are often surprised to learn that many vegetarian dishes, which can contain dairy and eggs, have a higher Carbon Cost than some dishes that contain animal meat. Take, for example, the vegetarian Spinach, Cheddar, and Tomato omelet in the above menu, with a Carbon Cost of 6 miles, compared to the meat-based fish and chips main, with a Carbon Cost of 3 miles.  Carbon Cost takes into account the entire life-cycle of the animal, and products such as cheese, which comes from cows, can have an even higher Carbon Cost than some animal products like chicken or fish.

Impact of Menu Pricing on Portion of Dishes Sold

Lady Margaret Hall’s canteen is only open to its student and faculty community, and it offers subsidised dishes compared to those at a restaurant or facility open to the public. We suspect that if consumers had to bear the full price for these menu items, the impact of Carbon Costing would be even greater.

During this trial, there was no meal choice that included beef, which typically has the highest Carbon Cost of any animal-based meat product.  We speculate that if the menu had included such an item, it would have led to an even more pronounced shift in meal choices during the Carbon Cost trial. Nevertheless, the carbon-based pricing model drove a wedge between the cost of plant-based and meals that contain animal products (both meat and vegetarian) compared to the period of normal pricing.

Carbon Cost PricingRegular Pricing
Plant Based (Vegan)£1.00£2.75
Animal Based£3.50£3.08
Other (vegetarian meals with egg or dairy) £3.50£2.54
Average£2.67£2.79

Carbon Costed Menus Change Consumer Behavior to Help the Environment

Our limited trial at LMH suggests you can immediately change consumer demand by using Carbon Cost as a pricing tool. This pricing scheme had a significant impact on consumer choices that went beyond what is typical when you simply present carbon footprint information without altering the prices.

It is important to note that in this trial Carbon Costing does not necessarily harm a food service facility’s overall revenues.  Since many habits are sticky, most consumers will continue to eat meat-based dishes even at higher prices.  We believe the higher pricing has potential to compensate for a reduction in orders of meat-based menu items.  At Lady Margaret Hall, when we instituted Carbon Cost pricing, overall revenues were slightly higher £3,183 (£3.03 per diner), compared to just £2,888 (£2.93 per diner) during the period of normal pricing.

This trial was part of our Carbon Cost of Food Week, a special event with numerous participants in and around Oxford, UK.  We provide a tool to help participants estimate the carbon footprint, or Carbon Cost, of their food choices in car miles, and we encouraged local food businesses to increase transparency of the carbon footprints of their menus. Participation in 2024 tripled compared to 2023. We look forward to other opportunities to test out the power of the Carbon Cost.