Switching to a more sustainable diet could halve food-related emissions in cities such as Amsterdam, while in cities such as Dhaka and Delhi, the focus should be more on making food production more sustainable as they widen food access. A new database by Leiden researchers shows that different cities need different approaches to achieve a more sustainable food system.
Researchers at the Institute of Environmental Sciences (CML) examined the climate impact of dietary patterns in cities around the world. To do so, they developed a database that maps greenhouse gas emissions linked to food consumption in 12,228 cities across 159 countries.
The study shows that the world's 200 largest cities together account for almost half of all urban food-related emissions. But the drivers behind those emissions vary greatly from city to city.
Different cities, different recipes
The researchers looked at the effects of the EAT-Lancet diet, an internationally recognised dietary pattern that combines health and sustainability. In wealthier cities, adopting such a diet often leads to substantial emission reductions.
'In the Netherlands, the greatest gains can be achieved through dietary changes, such as eating less meat.'
'In the Netherlands, food supply chains are already relatively efficient,' says first-author Hongyi Cai. 'That means the greatest gains can be achieved through dietary changes, such as eating less meat. In Amsterdam, switching to the EAT-Lancet diet could reduce emissions by around 45 to 50 per cent.'
But this does not apply everywhere. In cities such as Dhaka and Delhi, following the same diet could actually increase emissions. This is because people there already eat fewer animal-based products on average.
'For these cities, we need to expand access to nutritious food while keeping the environmental costs as low as possible,' says co-author Shruti Jain. 'The main challenge is ensuring that people have access to a sufficient variety of nutritious foods, such as pulses, nuts and vegetables, while also making the supply chains that produce them more sustainable.'
Four types of cities
Dietary patterns explain around 48 per cent of the differences in emissions between the cities studied. The efficiency of the food supply chain explains a further 48 per cent. Demographic factors, such as the age structure of the population, explain the remaining 4 per cent. Based on these findings, the researchers identified four types of cities, each requiring a different approach.
1. Consumption-driven cities
Food supply chains are relatively efficient, but people consume many products with a high climate impact, such as meat and dairy. The greatest opportunities for reducing emissions lie in changing dietary habits.
Examples: Paris, Berlin
2. Production-driven cities
People already eat relatively plant-based diets, but food production, processing and transport generate high emissions. Here, the greatest potential lies in making the food supply chains more sustainable.
Examples: Jakarta, Dhaka
3. Mixed cities (cities facing two challenges)
Both dietary patterns and food supply chains contribute significantly to emissions.
Examples: Lima, São Paulo
4. Cities with limited data
These cities still lack enough data to determine exactly where the biggest problems lie or which measures would be most effective.
Example: Cairo
It is not just about what is on the plate
The comparison between Lima and Paris shows that sustainability is not determined solely by what people eat. Although people in Lima have a more plant-based diet, food-related emissions in Peru are three times higher than in the French capital.
This is because food production and distribution are less efficient in Lima, says Cai. 'It comes down to how food is produced, processed and transported.'
From insight to action
To help cities better understand their own situation, the team developed the MATILDA-City online platform. The database shows which foods and consumer groups have the greatest impact. It also shows whether people are consuming enough healthy foods, such as fruit vegetables and pulses. Cities can compare their situation with other cities and see which measures are likely to be the most effective.
'Many cities have ambitious climate targets, but lack the data needed to determine which measures will have the greatest impact,' says co-author Oliver Taherzadeh. 'Our database helps fill that gap.'
There may be no universal recipe for a more sustainable food system, but there are increasingly better ingredients for tailored solutions.
Scientific paper
Hongyi Cai et al. 2026 Environ. Res. Lett. 21 164007 DOI 10.1088/1748-9326/ae9328
This work was supported by the Horizon Europe 2020 Framework GreenGrocer project (Project No:101182025).
