From beef at the top to nuts at the bottom, for each product you can see from this chart, built by Our World in Data, which stage in the supply chain a food's emissions originate. This extends from land use changes on the left, through to transport and packaging on the right.
In this comparison we look at the total GHG emissions (shown as CO2e) per kilogram of food product. CO2 is the most important GHG, but not the only one – agriculture is a large source of the greenhouse gases methane and nitrous oxide. To capture all GHG emissions from food production researchers therefore express them in kilograms of ‘carbon dioxide equivalents’ (CO2e). This metric takes account not just CO2 but all greenhouse gases.
The data in this chart came from the largest meta-analysis of global food systems to date, published in Science by Joseph Poore and Thomas Nemecek (2018).
The most important insight from this study is probably that there are massive differences in the GHG emissions of different foods: producing a kilogram of beef emits 60 kilograms of CO2e. While peas emits just 1 kilogram per kg.
Overall, animal-based foods tend to have a higher footprint than plant-based. Lamb and cheese both emit more than 20 kilograms CO2e per kilogram. Poultry and pork have lower footprints but are still higher than most plant-based foods, at 6 and 7 kg CO2e, respectively.
For most foods – and particularly the largest emitters – most GHG emissions result from land use change (shown in green), and from processes at the farm stage (brown). Farm-stage emissions include processes such as the application of fertilizers – both organic (“manure management”) and synthetic; and enteric fermentation (the production of methane in the stomachs of cattle). Combined, land use and farm-stage emissions account for more than 80% of the footprint for most foods.
In most cases, transport is a small contributor to emissions. It accounts for less than 10%, and it’s much smaller for the largest GHG emitters. In beef from beef herds, it’s 0.5%. Not just transport, but all processes in the supply chain after the food has left the farm – processing, transport, retail and packaging – mostly account for a small share of emissions.
The exception is food that travels by air. In Australia, this means anything that is perishable, which has to be flown in from overseas. Flying emits 50 times more CO2e than boat per ton kilometre.
The important take aways here are that whether you buy food from the farmer next door or from far away, it is not the location that makes the carbon footprint of your dinner large, but the fact that it is beef or lamb or peas. Plant based food is an exception. Even when shipped at great distances, its emissions are much less than locally-produced animal products.
Eating local matters for freshness, health and supporting your local economy and community, which is usually the place that supports you.
This chart is from Our World in Data and they in turn got their data from the largest meta-analysis of global food systems to date, published in Science by Joseph Poore and Thomas Nemecek (2018). In this study, the authors looked at data across more than 38,000 commercial farms in 119 countries.