What contributes more to life-cycle greenhouse gas emissions of farm produce: Production, transportation, packaging, or food loss?

The food production and supply systems are some of the biggest contributors to climate change, and food loss from the entire food chain aggravates the problem. We developed a model to estimate the GHG emissions from the entire food cycle (production, packaging, transportation, refrigeration, and waste management), and applied it to cherries, onions, and plums, the first time these produce have been assessed comprehensively in the United States. We pulled into the analysis 6 additional fruits and vegetables for which California accounts for more than 50% of U.S. production and which we have assessed at least partially earlier: strawberries, avocados, lemons, celery, oranges, and tomatoes. We assessed uncertainty for 34 parameters through Monte Carlo simulation. The total life-cycle food losses for one unit of cherries, onions, and plums produced are 66%, 57%, and 44%, respectively. The consumer stage contributes most of the food loss for eight of the nine produce. The results show that food loss contributes 19–61%, transportation 14–46%, packaging 11–31%, and farm production 7.7–30% to the total emissions. Alternative packaging was also explored. Polyethylene produce bags substituted with PLA bags can lower the total food-loss-inclusive emissions by only 7%, 5%, and 4% for tomatoes, oranges and onions, respectively. Forgoing retail-provided PE bags for produce that are not pre-packaged could reduce total GHG emissions by 12%, 10%, 6%, 6%, and 4% for one unit of tomatoes, onions, lemons, plums, and oranges, respectively. The GHG emissions for the 9 produce can be significantly reduced by decreasing consumer-level food loss. For tomatoes and onions, more than half of the emissions due to food loss can be offset by forgoing packaging at the retail stores.