Abstract
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-1 day-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.
Generated Summary
This research article investigates the greenhouse gas (GHG) emissions associated with U.S. dietary choices and food loss, utilizing a life cycle assessment (LCA) approach. The study examines the GHG emissions from food production, retail, and consumer-level losses, as well as the potential impact of shifts towards dietary recommendations, as outlined in the 2010 Dietary Guidelines for Americans. The methodology involves a meta-analysis of emission factors for various food types and the use of U.S. Department of Agriculture (USDA) food availability data. The research aims to quantify the environmental effects of food waste and the potential benefits of adopting healthier eating patterns.
Key Findings & Statistics
- Food losses at the retail and consumer levels contribute 1.4 kg of carbon dioxide equivalents (CO2-eq) per capita per day, which accounts for 28% of the average U.S. diet’s carbon footprint.
- In total, this is equivalent to the emissions of 33 million average passenger vehicles annually.
- Beef accounts for only 4% of the retail food supply by weight, but it represents 36% of the diet-related GHG emissions.
- A shift to USDA dietary recommendations could result in a 12% increase in diet-related GHG emissions.
- A shift that includes a decrease in caloric intake, based on population needs, results in a small (1%) decrease in diet-related GHG emissions.
- Food losses in the US retail and consumer levels in 2008 were 124 kg per capita per year.
- Total purchase value in 2008 was US$165.6 billion.
- The energy embedded in food waste in 2007 was 0.00214 exajoules, which is approximately 2% of annual energy consumption in the United States.
- Approximately one quarter of the produced food (on a food energy basis) is lost, accounting for 24% of total freshwater resources used in food crop production, 23% of global cropland area, and 23% of total global fertilizer use.
- Beef represented the single largest contributor from wasted food, with 16% of the total emissions.
- Production of food lost at retail and consumer levels in the United States in 2010 contributed an additional 160 MMT CO2-eq of GHG emissions.
- Emissions from food production total 573 MMT CO2-eq per year, or 8% of the total U.S. GHG emissions in 2010.
- A shift to a 2,534-Calorie recommended diet would cause a 12% overall increase in GHG emissions, whereas a shift to a 2,000-Calorie recommended diet would result in a 1% overall decrease in GHG emissions.
- At a 2,000-Calorie diet basis, the estimated GHG emissions from producing the standard food pattern diet, a lacto-ovo vegetarian adaptation, and a vegan adaptation are 3.6, 2.4, and 1.7 kg CO2-eq capita-1 day-1, respectively.
Other Important Findings
- Retail and consumer-level losses account for 31% (by weight) of the food available at the retail level.
- Grain products, fresh fruit, fresh vegetables, fluid milk, and added sugars make up the largest contributions to food loss.
- The distribution of GHG emissions is dominated by the meats category.
- The U.S. population is currently underconsuming fruits, vegetables, seafood, and dairy and overconsuming meat, poultry, and eggs, nuts, seeds, and soy, oils, and solid fats, and added sugars.
- A vegetarian diet shows a considerably lower carbon footprint (CF).
Limitations Noted in the Document
- The study uses a meta-analysis approach, drawing on existing LCA data, which may vary in system boundaries and methodologies.
- The USDA LAFA data set is a top-down approach to estimating food loss and consumption, which may overestimate per capita caloric intake.
- The study excludes losses from primary production weight to retail weight.
- The inability to consistently separate cooking losses from uneaten (wasted) food is a limitation in the LAFA data set.
- The study does not explicitly account for GHG emissions associated with disposal of food wastes.
Conclusion
The research underscores the significant environmental impact of food waste and the potential for dietary changes to mitigate GHG emissions. The production of food lost at retail and consumer levels in the United States generates substantial GHG emissions, comparable to the impact of millions of vehicles. While shifting to USDA dietary recommendations alone may not significantly decrease emissions, a vegetarian diet demonstrates a considerably lower carbon footprint. The study emphasizes the need to consider the environmental costs of food production when formulating food patterns. The current U.S. diet shows overconsumption of certain food groups, highlighting the potential benefits of aligning dietary choices with environmental goals. The complexity of dietary choices and the various factors influencing them underscore the need for collaborative efforts among businesses, governments, and consumers to address the environmental impact of the food system. The findings suggest that initiatives to reduce food waste and promote sustainable dietary patterns could significantly contribute to climate change mitigation. This includes exploring the synergy between nutritional guidelines and environmental sustainability to foster a more efficient and environmentally responsible food system. The research suggests that to meaningfully reduce GHG emissions, reducing food waste is a priority, alongside reducing meat consumption. It emphasizes that a shift towards a more sustainable diet is possible, but it requires a comprehensive approach that considers both nutritional and environmental aspects.