Where the numbers come from
The factors are greenhouse gases from farm to shop for each kg or litre: growing the crops, feeding animals, processing, packaging and transport. Most come from the largest study of food so far, by Poore and Nemecek (2018), as published by Our World in Data.
Animal foods weigh the most: beef and lamb because cattle and sheep emit methane, cheese and butter because they need a lot of milk. A litre of cola is mostly sugar, water, the bottle or can, and cooling.
Drinks in aluminium cans and glass bottles carry more packaging CO₂ than large plastic bottles; refillable glass bottles the least once reused.
Frequently asked questions
Why is chocolate so high?
Cocoa farms often replace forest, and the CO₂ from that land change is counted. Milk chocolate adds milk powder.
Are plant milks better?
Soy and oat milk put out about a third of the CO₂ of dairy milk per litre.
How big is 300 litres of cola?
About 120 kg of CO₂ a year, roughly what a petrol car puts out in 750 km.
Sources
- Our World in Data: environmental impacts of food ↗ – greenhouse gases per kg, from Poore and Nemecek (2018)