A new analysis from researchers in the Center for Sustainable Systems at the University of Michigan calculates that food waste in the US is associated with greenhouse gas emissions equivalent to more than 13% of the US automobile fleet. The good news is that the researchers also find that “real and important opportunities exist to improve the resource use efficiency and environmental impact of the U.S. food system that do not require increased yields or shifts in production practices, but are instead dependent on consumer behaviors”.

The researchers findings include that:

• Food losses at the retail and consumer levels contribute 1.4 kilograms carbon dioxide equivalents per person per day.
• Food losses add 28% to the overall carbon footprint of the average U.S. diet.
• An iso-caloric shift ( a shift in dietary intake that does not change the total number of calories consumed) 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.
• Globally, direct emissions from agriculture represent 10% to 12% of overall greenhouse gas (GHG) emissions; when including the impact of fertilizer and chemical production, fuel use, and agriculturally induced land-use change (which carries large uncertainty), the figure rises to 17% to 32%.
• Though transportation, housing, and food (in that order) are the largest contributors to the carbon footprint of the typical U.S. household, dietary changes are among the most economically effective abatement options.
• Food overconsumption and obesity contribute not only to human health dangers, but also translate directly and indirectly
  into increased agricultural demand, excess resource utilization, and concomitant environmental impacts.
• Dietary choices ultimately drive the makeup of food purchases and consumption patterns, which will also affect the GHG emissions associated with food losses.

While GHG emissions are only one of numerous environmental impacts to be considered, this research speaks to the need to incorporate the environmental costs of food production into dietary recommendations. Increasing the efficiency of our food system by reducing food waste and improving diets is an important strategy for climate change mitigation and requires collaborative efforts by businesses, governments, and consumers.

The 10 page paper is available at http://onlinelibrary.wiley.com/doi/10.1111/jiec.12174/full