| Greenhouse gas emissions factor | kg eCO2 / kg food | Heller and Keoleian 2014, Greenhouse gas emission estimates of US dietary choices and food loss, Journal of Industiral Ecology DOI: 10.1111/jiec.12174 | https://onlinelibrary.wiley.com/doi/abs/10.1111/jiec.12174 | kg eCO2 / kg food | Greenhouse gas emissions factors were collected from Heller & Keoleian 2014 for the food categories in SIMAP. The factors in Heller & Keoleian 2014 are averages by food category based on a literature survey conducted for the paper. Transport emissions for average food miles are included in these emissions factors. | 2017, 2018, 2019, 2020, and 2021 |
| Greenhouse gas emissions factor for local food | kg eCO2 / kg food | Heller and Keoleian 2014, Greenhouse gas emission estimates of US dietary choices and food loss, Journal of Industiral Ecology DOI: 10.1111/jiec.12174; Weber and Matthews 2008, Food-miles and the relative climate impacts of food choices in the United States, Environmental Science & Technology 15: 3508-13. | https://onlinelibrary.wiley.com/doi/abs/10.1111/jiec.12174; https://www.ncbi.nlm.nih.gov/pubmed/18546681 | (kg eCO2 / kg food) * (1 - 3%) | 250 miles was selected because it is a widely used average for local food miles. The greenhouse gas emissions factors from Heller & Keoleian 2014 were modified to reduce the tranport emissions. It was assumed that final transport accounts for 4% of greenhouse gas emissions from food (Weber & Matthews 2008), so the Heller & Keoleian 2014 emissions factors were reduced by 3% overall to account for a roughly 75% reduction in transport miles. | 2017, 2018, 2019, 2020, and 2021 |
| Greenhouse gas emissions factor | kg eCO2 / kg food | J. Poore, T. Nemecek, Reducing food’s environmental impacts through producers and consumers.Science360,987-992(2018).DOI:10.1126/science.aaq0216 | https://www.science.org/doi/10.1126/science.aaq0216 | kg eCO2 / kg food | Greenhouse gas emissions factors were collected from Poore & Nemecek 2018 and align with WRI's Coolfood Pledge Calculator. | 2022, 2024, and 2025 |
| Greenhouse gas emissions factor for local food | kg eCO2 / kg food | Weber and Matthews 2008, Food-miles and the relative climate impacts of food choices in the United States, Environmental Science & Technology 15: 3508-13. | https://www.ncbi.nlm.nih.gov/pubmed/18546681 | (kg eCO2 / kg food) * (1 - 3%) | 250 miles was selected because it is a widely used average for local food miles. It was assumed that final transport accounts for 4% of greenhouse gas emissions from food (Weber & Matthews 2008), so food emissions calculations are reduced by 3% overall to account for the local transport distance. | 2022, 2024, and 2025 |
