This came up in class: contribution of transportation to GHG emissions
During tonight’s class, someone asked about the relative contribution of transportation to a product’s total GHG emission, and how the GHG emissions of vegetables/grains compare with meat. After a bit of digging, I found the following peer-reviewed research paper published last year – here’s the abstract (and here’s the paper):
Despite significant recent public concern and media attention to the environmental impacts of food, few studies in the United States have systematically compared the life-cycle greenhouse gas (GHG) emissions associated with food production against long-distance distribution, aka “food-miles.” We find that although food is transported long distances in general (1640 km delivery and 6760 km life-cycle supply chain on average) the GHG emissions associated with food are dominated by the production phase, contributing 83% of the average U.S. household’s 8.1 t CO2e/yr footprint for food consumption. Transportation as a whole represents only 11% of life-cycle GHG emissions, and final delivery from producer to retail contributes only 4%. Different food groups exhibit a large range in GHG-intensity; on average,red meat is around 150% more GHG intensive than chicken or fish. Thus, we suggest that dietary shift can be a more effective means of lowering an average household’s food-related climate footprint than “buying local.” Shifting less than one day per week’s worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food.
If there are any experts out there reading this, please weigh in the comments – was this study performed properly? How valid are their assumptions?