New Global Database Shows Why No Two Cities' Food Emissions Look the Same

Researchers at Leiden University's Institute of Environmental Sciences (CML) have built a database mapping greenhouse gas emissions linked to food consumption in 12,228 cities across 159 countries. Published in the journal Environmental Research Letters, the study found that the world's 200 largest cities together account for almost half of all urban food-related emissions.

The researchers examined the effect of adopting the EAT-Lancet diet, an internationally recognized dietary pattern that combines health and sustainability. In Amsterdam, switching to it could cut emissions by around 45% to 50%, said first author Hongyi Cai, because the Netherlands' food supply chains are already efficient and the biggest gains come from eating less meat. But in cities such as Dhaka and Delhi, where people already eat fewer animal products, the same diet could actually increase emissions, said co-author Shruti Jain, who argued these cities instead need wider access to nutritious food alongside more sustainable supply chains.

Dietary patterns explain about 48% of the differences in emissions between the cities studied, the researchers found, while the efficiency of food supply chains explains a further 48% and demographic factors such as age structure account for the remaining 4%. Based on this, the team grouped cities into four types: consumption-driven cities such as Paris and Berlin, where efficient supply chains mean dietary change offers the biggest gains; production-driven cities such as Jakarta and Dhaka, where largely plant-based diets are undercut by high-emission food production; mixed cities such as Lima and Sao Paulo, facing both challenges; and cities such as Cairo, where data remains too limited to pinpoint the biggest problem.

Although people in Lima eat a more plant-based diet than those in Paris, food-related emissions in Peru are three times higher than in the French capital, the researchers found, because food production and distribution are less efficient in Lima. The team has also built an online platform called MATILDA-City, so cities can compare their food emissions with others and identify the most effective measures.