Measurement and communication of greenhouse gas emissions from U.S. food consumption via carbon calculators

Food consumption may account for upwards of 15% of U.S. per capita greenhouse gas emissions. Online carbon calculators can help consumers prioritize among dietary behaviors to minimize personal "carbon footprints," leveraging against emissions-intensive industry practices. We reviewed the fitness of selected carbon calculators for measuring and communicating indirect GHG emissions from food consumption. Calculators were evaluated based on the scope of user behaviors accounted for, data sources, transparency of methods, consistency with prior data and effectiveness of communication. We found food consumption was under-represented (25%) among general environmental impact calculators (n=83). We identified eight carbon calculators that accounted for food consumption and included U.S. users among the target audience. Among these, meat and dairy consumption was appropriately highlighted as the primary diet-related contributor to emissions. Opportunities exist to improve upon these tools, including: expanding the scope of behaviors included under calculations; improving communication, in part by emphasizing the ecological and public health co-benefits of less emissions-intensive diets; and adopting more robust, transparent methodologies, particularly where calculators produce questionable emissions estimates. Further, all calculators could benefit from more comprehensive data on the U.S. food system. These advancements may better equip these tools for effectively guiding audiences toward ecologically responsible dietary choices.