Greenhouse Gas Emission Estimates of U.S. Dietary Choices and Food Loss

Summary

Dietary behavioral choices have a strong effect on the environmental impact associated with the food system. Here, we consider the greenhouse gas (GHG) emissions associated with production of food that is lost at the retail and consumer level, as well as the potential effects on GHG emissions of a shift to dietary recommendations. Calculations are based on the U.S. Department of Agriculture's (USDA) food availability data set and literature meta-analysis of emission factors for various food types. Food losses contribute 1.4 kilograms (kg) carbon dioxide equivalents (CO₂-eq) capita⁻¹day⁻¹ (28%) to the overall carbon footprint of the average U.S. diet; in total, this is equivalent to the emissions of 33 million average passenger vehicles annually. Whereas beef accounts for only 4% of the retail food supply by weight, it represents 36% of the diet-related GHG emissions. An iso-caloric shift from the current average U.S. diet to USDA dietary recommendations could result in a 12% increase in diet-related GHG emissions, whereas a shift that includes a decrease in caloric intake, based on the needs of the population (assuming moderate activity), results in a small (1%) decrease in diet-related GHG emissions. These findings emphasize the need to consider environmental costs of food production in formulating recommended food patterns.