Study: High emissions could make healthy diets unaffordable to millions

Climate-driven changes in crop yields could leave an additional 119 million people unable to afford a healthy diet by the end of the century under a high-emissions scenario, according to a modeling study published in the journal The Lancet Planetary Health.

The research shifts the focus from a question scientists have long asked — whether the world can produce enough food — to one they have rarely quantified on a global scale: whether people can actually afford nutritious meals as the climate changes.

To answer the question, an international research team from institutes in China, France, the United States, and Germany built a coupled modeling framework. They used global gridded crop models to simulate how climate change affects the yields of major crops, then fed those results into GCAM — a global integrated assessment model — to simulate the resulting changes in agricultural production, land use, and food prices.

Building on this, the study applied the Food and Agriculture Organization's framework for measuring the cost and affordability of healthy diets, combined with regional income distributions under different socioeconomic pathways, to assess how people's ability to afford healthy diets will change globally and regionally.

The results showed that the impact of climate change on diet affordability is highly dependent on the emissions trajectory the world follows. Under low- and medium-emission scenarios, the global ability to afford a healthy diet remains relatively stable.

However, a high-emission scenario would see climate-driven changes in crop yields significantly increase the number of people unable to afford a healthy diet in the future. The model projects that by 2100, around 119 million additional people worldwide could lose the ability to afford healthy diets as a direct result of these climate-driven yield changes.

Additionally, the burden falls unevenly, according to the study. Some regions with lower baseline economic development, slower income growth, and more fragile food systems face disproportionately larger increases in diet unaffordability. Often, these are the same regions that contribute less to global greenhouse gas emissions.

The study's co-first authors are Jiang Yongye, a doctoral student at Peking University's College of Urban and Environmental Sciences, and Fu Bo, an associate researcher at the university's School of Public Health. Li Bengang, a professor at the College of Urban and Environmental Sciences, is the corresponding author of the study.