Background One of the most important consequences of climate change could be its impact on agriculture. While much research has focused on questions of food security, less attention has been devoted to assessing the wider health impacts of future changes in agricultural production. We estimate excess mortality due to agriculturally mediated changes in dietary and weight-related risk factors by cause of death for 155 world regions in the year 2050.

Methods We linked a detailed agricultural modelling framework, the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT), to a comparative risk assessment of changes in fruit and vegetable consumption, red-meat consumption, and body weight for deaths from coronary heart disease, stroke, cancer, and an aggregate of other causes. We calculated the change in the number of deaths due to climate-related changes in weight and diets for the combination of four emissions and three socio-economic pathways, which each included six scenarios with variable climatic inputs.

Results The model predicts that by 2050 climate change will lead to per-capita reductions of 3%, 4%, and 1% in global food availability, fruit and vegetable consumption, and red-meat consumption, respectively. Those changes were associated with 529,000 climate-related deaths globally (95% CI: 314,000–736,000), representing a 28% reduction in the number of deaths that would be avoided due to changes in dietary and weight-related risk factors between 2010 and 2050. Twice as many climate-related deaths were associated with reductions in fruit and vegetable consumption than with climate-related increases in the prevalence of underweight, and most climate-related deaths were projected to occur in South and East Asia. Adopting climate-stabilisation pathways reduced the number of climate-related deaths by 29–71% depending on their stringency.

Conclusion The health impacts of climate change from changes in dietary and weight-related risk factors could be significant, and exceed other climate-related health impacts that have been estimated. Climate change mitigation could prevent a substantial number of climate-related deaths. Strengthening public-health programmes aimed at preventing and treating diet and weight-related risk factors could be a suitable climate change adaptation strategy.