Food Loss and Waste (FLW) Greenhouse Gas Emissions.

Introduction

Fig. 1: Percent of the total amount of GHG emissions produced by US FLW by supply chain stage. [1] (Image source: I. Barrow)

The goal of this report is to investigate the potential of reducing food waste and loss (FWL) as a means of lowering greenhouse gas emissions (specifically in the U.S.). Greenhouse gases (GHG) are gasses that trap a portion of the Earth's outgoing energy, which in turn retains heat in the atmosphere. Some of the gasses considered greenhouse gases include carbon dioxide, methane, nitrous oxide, and some synthetic chemicals, including chlorofluorocarbons. Human activities are increasing the concentrations of greenhouse gasses, and this process has been the primary cause of the 1°C increase in global air surface temperature over the past 115 years. [1] Climate change's effects on global natural systems include increases in land, water, and air temperatures, variation in precipitation timing and amounts, reduced snowpack, sea level rise, and wildfires and hurricanes. The Paris Agreement has set global targets to limit global warming below 2°C and with aspirations to keep warming to 1.5°C because warming beyond 1.5°C is likely to lead to catastrophic outcomes. [1]

FLW in the US

A major contributor to greenhouse gas emissions is "food loss and waste" (FWL). The term "food loss and waste" is defined as food intended for human consumption but is not eventually consumed. Food grown primarily for animal consumption, biofuel, and any other uses besides human consumption is excluded from our definition. Any food that is donated to food banks or upcycled into new food products is also excluded from our definition. [1]

Different amounts of GHG emissions are produced during the different stages of the U.S. cradle-to-consumer food supply chain. Approximately 170 million MTCO₂e GHG emissions (excluding landfill emissions) are emitted every year in the U.S. as a result of FLW. [1] The EPA report of 170 million tonnes of GHG does not identify how much was a result of fossil fuel consumption, food rot, or other causes. To put the amount of CO₂ released from FWL into perspective, in 2021, the mass of crude oil produced globally totaled 4.22 billion tonnes. [2] With a mass ratio of 44/14, this results in 13.3 billion tonnes of CO₂ from consuming crude oil. In comparison to FWL in the U.S., crude oil consumption produces approximately 78 times as much CO₂.

There are four different stages of the U.S. cradle-to-consumer food supply chain: Primary production, distribution and processing, retail, and consumption. [1] As shown in Fig. 1, among the four stages of food production, primary production accounts for the most GHG emissions (48%), followed by distribution and processing (26%), retail (22%), and finally consumption (4%). [1]

In regards to global warming potential, the gases emitted from FLW are more potent than carbon dioxide. While carbon dioxide is a significant contributor to GHGs, methane is a GHG with more than 25 times the global warming potential of carbon dioxide. The most significant GHG with global warming potential is nitrous oxide, which has approximately 265 times more impact than carbon dioxide. Food production in the United States is responsible for approximately 39 percent of its methane emissions and approximately 80% of its nitrous oxide emissions. Combined, these emissions are approximately 4.72 kg CO₂e (CO₂ equivalents) per person per day. [1]

Different amounts of GHG emissions are released per food category. Per The Food and Agriculture Organization (FAO), when examining FLW by quantity, fruits and vegetables top the list at 40% of FLW. The significant FLW of milk, dairy, and eggs at 20% and 16%, respectively, was noted by the FAO. [1] The biggest food group contributing to the GHG of FLW is animal products, specifically ruminant-based. Beef, veal, and lamb were the biggest contributors to GHG. Animal products were responsible for 73% of GHG from retail and consumer stages despite only comprising 33% of FLW by weight and 23% by calories. [3]

Conclusion

The data presented in this report demonstrates that reducing food loss and waste in the US may be helpful but is not a significant means to help combat global warming. Even assuming a 100% reduction of FWL in the US, the amount of CO₂ produced is minimal in comparison to global GHG emissions, especially compared to the amount of CO₂ produced as a result of global fossil fuel consumption. However, the data supports that GHG emission reductions can still be achieved by primarily targeting reducing FLW production during animal product production. Initiatives towards reducing beef, veal, and lamb FLW should be implemented specifically because they produce the most GHG emissions. Because most FLW occurs during primary production, reducing FLW produced during primary production should take priority. Enacting policies that incentivize farms to reduce FWL during primary production appears to be the most promising method of lowering GHG emissions caused by FWL.

© Ian Park Barrow. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.

References

[1] "From Farm to Kitchen: the Environmental Impacts of U.S. Food Waste," U.S. Environmental Protection Agency, EPA 600-R21 171, November 2021.

[2] "BP Statistical Review of World Energy 2022," British Petroleum, June 2022.

[3] M. C. Heller and G. A. Keoleian, "Greenhouse Gas Emission Estimates of U.S Dietary Choices and Food Loss," J. Ind. Ecol. 19, 391 (2015).