Many of our foods are imported and sometimes come from far away. But it is precisely the transport of food that is responsible for a surprisingly large proportion of global greenhouse gas emissions, as a study reveals. According to this, the international and national transport of fruit, vegetables, grain, meat and co. generates CO2 emissions of around three gigatonnes worldwide, which corresponds to around 30 percent of the total emissions from food production without land use. These values are not only significantly higher than previously estimated, they are also significantly higher than when transporting other goods, as the research team reports. A more regionally and locally oriented diet could therefore benefit the climate.
Our diet not only affects our health, but also has consequences for the global environment and climate. This is because forests and other natural landscapes are being modified for the cultivation of food crops and animal feed, which affects their ability to absorb CO2. Processing and transporting food consumes energy and generates greenhouse gas emissions. Due to the increasing globalization of retail chains, the transport routes are becoming longer and longer, and food is often produced in areas that are not actually suitable for intensive cultivation, for example due to water shortages. This is one of the reasons why climate and nature conservationists have long been calling for more regional consumption.
Transport emissions higher than any other sector
Mengyu Li from the University of Sydney and her colleagues have now examined in more detail what role the transport of food from its place of production to the consumer plays in the ecological balance of the food sector. To do this, they developed a computer model that reconstructs the global food trading network based on global and national data on supply chains, emissions and transport routes. Using this model, the scientists determined the CO2 balance and transport routes for food globally and in 74 countries, for 37 different economic sectors and four modes of transport. In total, they evaluated around 30 million direct trade connections. From this, the team was able to determine the length of the transport routes and the volume of the goods transported for a wide variety of foods and countries.
The evaluation showed that the food sector is responsible for around 15.8 gigatonnes of CO2 per year, which corresponds to around 30 percent of global CO2 emissions. The climate impacts of land use changes for agriculture are not yet included, as the researchers explain. Of these food-related emissions, around three gigatonnes are attributable to the national and international transport of food alone. “This value is 3.5 to 7.5 times higher than previous estimates,” Li and her colleagues report. At the same time, the comparative analyzes showed that transport accounts for 30 percent of the total greenhouse gas budget for food production; if you add the land use effects, the figure is 19 percent. “This means that the transport emissions in the food sector are far higher than those of other goods: In general, freight is only responsible for around seven percent of the CO2 balance of industry and goods production,” explains the team.
Rich countries in particular drive long-distance food transport
According to the data, CO2 emissions are particularly high for fruit and vegetables: Because they are heavy, often transported over long distances and have to be cooled, the transport of these foods has a disproportionately large impact on the greenhouse gas balance. “Transportation of vegetables and fruits more than doubles their production-related emissions from 0.5 gigatonnes of CO2-equivalent to 1.1 gigatonnes annually,” Li and her colleagues report. If you compare different countries and regions, there are clear differences in terms of the transport routes of imported or exported food and the associated carbon footprint. According to this, the USA, China, India and Russia have the highest share of transport-related emissions from the food industry, but smaller, rich countries also make a major contribution: “The richest countries represent around 12.5 percent of the world population, but are responsible for 46 percent of the world’s population food kilometers traveled internationally and the associated emissions,” writes the research team.
According to the scientists, not only meat consumption should be reduced for a more climate-friendly food production, but also the extent of long-distance transport of food. “So far, research into more sustainable food production has focused primarily on comparing animal-based with plant-based nutrition,” says Li’s colleague David Raubenheimer. “Our study now shows that, in addition to switching to a more plant-based diet, the change to a more regional and local diet makes sense.” In addition to politics and business, consumers are also asked here: If they accept that seasonal fruit and vegetables are not available locally all year round, this could save many long-distance transports of such food. At the same time, it is also the task of retailers, food chains and other providers to increase the proportion of locally produced food in the shops and make them more attractive to customers. “If we change the attitudes and behavior of individuals towards sustainable nutrition, then this will benefit the environment on a large scale,” says Raubenheimer.
Source: Mengyu Li (University of Sydney) et al., Nature Food, doi: 10.1038/s43016-022-00531-w