Supply chain emissions from food are between 3.5 and 7.5 times higher than previous estimates because the contribution of transport has been massively underreported, according to a study.
The study of 74 regions, 37 economic sectors, four transport modes (water, rail, road and air) and more than 30m trade connections (journeys of a single food from one place to another) found 19% of global food system greenhouse gas emissions are caused by transportation.
Researchers used a framework called FoodLab to gauge “food miles” emissions at around three gigatonnes annually.
This far exceeds transport emissions of other sectors – industry and utilities transport, for example, contributed just 7%. Taking into account transport, production and land use change, global food chains contribute about 30% of total human-produced greenhouse gas emissions, or 16bn tonnes annually.
Some 36% of food transport emissions were caused by the global shipping of fruit and vegetables – almost twice the emissions released during their production. Vegetables and fruit require temperature-controlled transport which pushes their food miles emissions higher.
Additionally, high-income countries were greater contributors – despite being 12.5% of the global population, they generate 46% of international food miles emissions. Low-income countries, with around half the global population, cause only 20% of food transport emissions.
The largest net exporter of food miles was Brazil, followed by Australia, India and Argentina. Australia is a primary producer of fruits and vegetables that are exported to the rest of the world.
Professor David Raubenheimer, nutritional ecologist and co-author, said: “Prior to our study, most of the attention in sustainable food research has been on the high emissions associated with animal-derived foods, compared with plants. Our study shows that in addition to shifting towards a plant-based diet, eating locally is ideal, especially in affluent countries.”
Eating food grown and produced locally helps mitigate emissions associated with food transport. “Locally” means eating food grown within a 161km radius of one’s home.
The study suggests four further courses of action for businesses and governments to help reduce food transport emissions:
Increase carbon pricing and import duties
Invest in less-polluting vehicles
Cut emissions in production and distribution chains
Introduce planning laws that allow urban agriculture projects