Should Carbon Footprint Labeling Be Mandatory for All Food Products? Rct Shows No Benefit Beyond Labeling the Top Third

Carbon footprint labels have been shown to lead consumers to choose food products with lower CO2 emissions, but an unresolved issue is what proportion of food products must be labeled for labeling to be effective. We asked 1,081 American consumers to shop in an experimental online grocery store and choose one frozen meal among the full assortment of a major American grocer in a control (no label), 33% labeled (the third of products with the lowest carbon footprint were labeled), 67% labeled (the top two thirds were labeled) and all labeled condition. A 16.5% reduction in emissions was achieved by labeling the top third of products, with no statistically significant improvement gained by further increasing the proportion of labeled products. Mandating all products, including the least virtuous, to be labeled may therefore not be necessary to promote sustainable diets if the most virtuous products self-select into labeling