Total greenhouse gas emissions from producing and delivering a food item, measured in kg CO2-equivalent per serving or per kg.
A food's carbon footprint is its cradle-to-fork greenhouse gas emissions β from land use and feed production through farm operations, processing, packaging, transport, retail, and cooking β measured in kg CO2-equivalent (CO2e, a unit that combines CO2, methane, and nitrous oxide into a single number).
Ranges vary enormously: beef averages 27 kg CO2e/kg (methane from cattle dominates); lamb 24; cheese 21; pork 7; chicken 6; fish 5; eggs 4.5; tofu 3; root vegetables 0.4; nuts 0.3. Transport ("food miles") is usually under 10% of the total β land use and livestock dominate.
Quarter-pound beef burger
~3 kg CO2e per patty (land + methane)
Same weight of lentils
~0.1 kg CO2e