Here’s what you need to know: A UK café experiment shows that making oat milk the default option can slash the carbon footprint of cafe drinks by up to 34%. Researchers at Plymouth Marjon University tested this by switching oat milk to the default at one campus café, while a second café served as a control. The results? Plant-based milk use tripled in just weeks, with carbon savings matching the scale of the shift.
The study, published in Global Environmental Psychology, used an ABAB design to track changes over time. Before the default nudge, plant-based milk accounted for just 16.6% of orders. When baristas announced oat milk was now the default—framed as an environmental choice—usage spiked to 51.9%. Even after the nudge was removed, the rate held steady at 46%, far above the 16-18% baseline at the control café. The carbon footprint per drink dropped by 25-34%, depending on the data set used, with milk alone responsible for 0.79kg of CO2-equivalent in the baseline and 0.56kg under the nudge.
This isn’t just about milk. The study highlights how subtle changes in choice architecture can steer consumers toward sustainable habits without overt persuasion. By framing the default shift as an environmental win, the café turned a simple operational tweak into a powerful tool for reducing emissions. The university’s “net-zero” goals became a real-world testbed, proving that small interventions can yield measurable impact.
The takeaway? Default nudges work. They don’t require complex messaging or radical behavior change—just a shift in what’s offered first. For cafes, this means rethinking menus to align with sustainability without sacrificing customer choice. For consumers, it’s a reminder that the way options are presented shapes decisions, often without us realizing it.
Would you trade cow’s milk for oat.
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Questions & Answers
How does the default nudge affect oat milk sales?
The nudge tripled plant-based milk use, with 51.9% of orders switching to oat milk. Sales remained high even after the nudge was removed, at 46%.
What’s the carbon footprint reduction from the nudge?
The nudge cut the carbon footprint of cafe drinks by up to 34%, matching the scale of the shift to plant-based milk.
Information sourced from industry reports and news outlets.
