As sustainability climbs ever higher on political and societal agendas, so does awareness of the climate impact of what we eat. Scientists have long warned about the large environmental footprint of animal products, but how do you actually get consumers to change their behaviour? Tabea Krauss, PhD researcher in Law and Economics at Erasmus School of Law, investigates whether price labels that reveal the environmental damages caused by food can encourage people to make more sustainable choices. We spoke to her about her research's motivation and key findings.
From awareness to behavioural change
Krauss has been a vegetarian for many years and thus always tried to be mindful of the ethical and environmental impacts of what she ate. However, it was not until she began her PhD that she truly grasped the scale of the environmental impact of the global food system. "Researchers have found that global food supply chains account for approximately 26% of humanity’s greenhouse gas emissions worldwide," she explains.
What struck her most was discovering how big the environmental impact of even vegetarian diets still is. Krauss elaborates: "Foods from animal origin are notably more harmful to our planet than plant-based foods, and dairy products such as yoghurt and cheese also play a major role in this. In fact, of all agricultural practices, cattle farming, including dairy cows, is the most environmentally damaging one, not only in terms of emissions but also due to land use and water pollution."
When Krauss came across a database compiled by the Dutch National Institute for Public Health and the Environment (RIVM), which publishes the environmental impact of Dutch food products calculated based on lifecycle analysis, she saw an opportunity. "I wanted to use this great data source and test whether consumers would change their food choices when presented with their 'real costs'," she says.
Different prices for the same sandwich
To test this, Krauss designed a three-month field experiment in two university cafeterias. In the control cafeteria, nothing changed. In the experimental cafeteria, however, standard price tags were supplemented with an extra label showing the carbon-neutral price: the amount a product would cost if its hidden environmental costs, such as emissions, water use and pollution, and land use and pollution, were included. Krauss explains this concept is known as 'environmental true pricing'.
Customers in the experimental cafeteria could choose whether to pay the regular price or the carbon-neutral price. The additional revenue from the latter was donated to Trees for All, a Dutch registered charity organisation that plants trees and supports climate projects.
What happens when the impact becomes visible?
Krauss set out with two key research questions: would people make different food choices if they were informed about the environmental impact of their lunch, and would they be more likely to pay the carbon-neutral price for plant-based options?
Although the idea of 'paying for hidden environmental costs' is a topical issue, the observed effects on consumer behaviour were limited. Sales of both meat and vegan sandwiches rose marginally, while sales of vegetarian sandwiches slightly fell. However, to Krauss's disappointment, none of these changes proved statistically significant.
One possible explanation is that consumers did not find the environmental difference between meat or fish and vegetarian products big enough to influence their decisions. "Some customers might have thought, 'If there is not such a big difference, I might as well pick the meat option'," Krauss suggests. Meanwhile, some vegetarians may have shifted towards vegan options out of guilt over learning about the impact of dairy.
Will you choose the carbon-neutral price?
Even though purchasing behaviour barely changed, some customers were willing to pay the carbon-neutral price. Interestingly, this occurred most often for vegetarian sandwiches (32%), followed by meat (29%), and vegan (26%). Krauss suspects vegetarians may have felt a stronger sense of responsibility upon learning that dairy products are not necessarily much more sustainable than meat or fish.
A survey conducted after the experiment gave insights into which factors influence sustainable choices. People with a vegan lifestyle, strong environmental identity, or support for climate policies were more likely to opt for sustainable options. Age, gender, or whether participants were employees or students showed no significant influence.
Environmental true pricing as a policy tool
Krauss's experiment ties in with broader EU policy developments, such as the proposed and widely-debated Green Claims Directive. "Under this new regulation, EU companies would no longer be permitted to use broad or vague carbon neutrality claims in advertising but would instead be required to scientifically substantiate such claims," she explains. According to Krauss, true pricing labels based on lifecycle analysis could reflect the principles of this approach. Nevertheless, she concludes that voluntary price incentives may not be enough: "Since our study did not observe a significant shift in consumer behavior in response to voluntary price differences alone, we suggest that such compensatory price adjustments may need to be introduced mandatorily through taxes or levies in order to effectively reduce food-related greenhouse gas emissions within the EU."
A plant-based campus of the future?
At Erasmus University Rotterdam (EUR), the food offering is already a topic of debate. Since 2022, an ongoing discussion has been about whether the campus should become fully plant-based. Krauss explains: "Conversations with students and staff apparently showed that there is not enough support for this ambition yet. So instead, EUR is currently working towards adopting the Planetary Health Diet model, which allows up to 20% animal-based products."
Krauss sees this as a step in the right direction, but believes universities should go further, given that they are often seen as role models in our society. "A fully plant-based campus could significantly reduce EUR's emissions and also encourage students and staff to explore different eating habits. I think many of our daily food choices are driven by habit and familiarity, and a university is exactly the kind of space where we could question those habits and introduce more sustainable and healthier alternatives."
Krauss herself has now adopted a fully vegan diet. Nevertheless, even in the Netherlands, which is relatively vegan-friendly compared to many countries, she finds the options outside of university limited. "With everything we know about the environmental and ethical impact of foods of animal origin, plant-based options should not be rare or limited to a single 'vegan alternative' on the menu - they should be the norm."
Hope for change
According to Krauss, the key to behavioural change lies not only in policy but also in awareness, transparency, and the creation of space for new habits. "I hope I have sparked some people's interest in the environmental consequences of food consumption, and I hope I have contributed to raising awareness that, on average, plant-based foods are much less harmful to our planet than foods of animal origin."
Looking ahead, she hopes to contribute to a broader transformation of the food system, in which sustainable, plant-based choices become the standard rather than the exception. However, for now, she says: "I am incredibly grateful that my PhD gave me the chance to explore this topic and share those insights - even if they only reached a small circle of people around me, that still matters and means a lot to me."
- PhD student
