Food Waste, Animal Products, And Greenhouse Emissions

Researchers at the University of Michigan set out to calculate the greenhouse gas (GHG) emissions associated with the production of food that is lost and/or wasted at the retail and consumer levels. They also evaluated the potential effect on GHG emissions resulting from a shift to the dietary recommendations noted within the 2010 Dietary Guidelines for Americans.

The large impact that agriculture and food production have on resource use and environmental sustainability has been well-established. But, we still face major food security concerns worldwide. Direct emissions from agriculture represent 10–12% of overall global GHG emissions. The figure rises to 17–32% when we account for the impact of agricultural fertilizer, chemical production, fuel use, and land-use change. Many consider transportation and housing as the largest contributors to household carbon footprints. Yet several researchers argue that dietary changes are among the most economically effective changes that each of us can make to curb our CO₂ emissions.

Food waste is one such area in which most of us play a role. According to the United Nations’ estimates, roughly one third of the food produced worldwide for human consumption is lost or wasted. This amounts to 1.3 billion tons per year. Researchers estimate food losses in Germany, for example, to be 100–180kg per person per year. And 61% of these losses occur at the household level. Researchers from the U.S. Department of Agriculture (USDA) estimated food loss at the retail and consumer levels to be 124kg per person per year in the U.S. back in 2008. In recent years, the European Commission set a target to halve food waste in Europe by 2025.

In this study, the researchers produced an updated account of the GHG emissions associated with U.S. food losses at the retail/institution and consumer levels. They used data that they collected from other literature. The researchers also explored the implications for GHG emissions resulting from a shift toward the food patterns recommended within the 2010 Dietary Guidelines for Americans.

Shockingly, food losses account for 31% (by weight) of food at retail and consumer levels. In terms of the GHG emission contribution, the meats category dominates. This is due to the high GHG emissions resulting from beef, lamb, and (to a lesser extent) pork production. And although beef accounts for only 4% (by weight) of the retail-level food supply, it contributes to 36% of the associated GHG emissions. The total wasted food at retail and consumer levels is roughly equivalent to the emissions generated by 33 million average passenger vehicles annually.

The researchers compared the current U.S. dietary preferences to those recommended in the 2010 Dietary Guidelines for Americans. They point out that the U.S. population as a whole is currently under-consuming fruits and vegetables, while over-consuming meat and eggs among other food items. For a 2,000kcal diet, the researchers estimated the GHG emissions resulting from the standard food pattern diet, a lacto-ovo vegetarian diet, and a vegan diet. The GHG emissions equate to 3.6, 2.4, and 1.7kg CO₂ per person per day, respectively. There are significant differences in these emission levels. But the 30% decrease when comparing standard and lacto-ovo vegetarian diets is roughly the same as the decrease that could be achieved by eliminating all retail- and consumer-level food losses (28%).

It is certainly not possible to eliminate all food losses. But efforts to reduce food waste could be combined with efforts to reduce meat consumption. This could achieve significant reductions in the overall carbon footprint of our food system. The researchers highlight the need to align both environmental and health objectives of food systems through dietary recommendations. Real and important opportunities exist to improve the efficiency of resource use and to lessen the environmental impact of the U.S. food system. And these opportunities do not require increased yields or shifts in production practices. They are instead dependent on improved consumer behaviors.

This study suggests that shifts from the current U.S. diet to the USDA recommended diet would not correspond to significant reductions in diet-related GHG emissions. So, advocates will find that this research confirms that only slight reductions in GHG emissions are possible when following the USDA diet recommendations. On the other hand, moving closer toward nutritionally adequate vegetarian and vegan adaptations of the diet recommendations show promise.