The unprecedentedly large scale research included analyzing health and climate data for 107,000 children under 5 from 19 different countries across six regions in Africa, Asia, and Latin America. Most previous work linking climate to diet diversity was focused on individual countries or regions, according to Meredith Niles, an assistant professor at the University of Vermont and lead author of the study. The new study takes a big data approach to encompass a much broader geographic and temporal scope.
“The relative impact of climate compared to some of these other factors like wealth, sanitation, education—that was surprising to me for sure,” said Niles.
By using a statistical technique called hierarchical modeling, the researchers were able to compare the relative significance that different groups of variables had on diet diversity. One cluster of variables controlled for agroecological conditions of the children’s environment, such as the amount of tree cover in an area or the time it would take to get from the household to a source of water. Other clusters controlled for geographic and socioeconomic factors such as local population density and household wealth.
For the climate variables, researchers collected data on the long-term averages of temperature and precipitation over 30 years for each survey location, as well as the temperature and precipitation anomalies prior to the survey year. Diet diversity was measured from 1 to 10, depending on how many food groups the child consumed in the 24 hours prior to the survey.
The researchers found that hotter temperatures, both long-term averages and short-term anomalies, were significantly correlated with low diet diversity in five of the six regions studied. On the flip side, years with higher-than-average rainfall were associated with greater diet diversity in the following year for three of the six regions. And in West Africa, this positive effect appeared to actually counteract the negative effects of hotter long-term temperatures. But even with these regional differences, researchers still concluded that hotter long-term temperatures have already had a negative impact on the diet diversity of children all across the world, and decisionmakers will need to consider the profound influence of these climate impacts on future adaptation efforts.“The more evidence we have the easier it will be to convince decisionmakers to support on-the-ground work for these complex issues,” wrote Brendan Fisher, coauthor of the paper and director of the Environmental Program at the Rubenstein School of Environment and Natural Resources at the University of Vermont, in an email.
Higher diet diversity is a reasonable indicator of good nutrition and food security, both of which are part of the United Nations’ Sustainable Development Goal 2, to achieve zero hunger by 2030. But according to a 2020 report on global food security and nutrition by the Food and Agriculture Organization, world hunger has been on the rise since 2015. By studying how climate affects global food systems, Niles and her colleagues are part of a wider research effort to turn this trend around.
“I think that these results are very interesting because they call for adaptation efforts that consider seriously the relationship between temperature, precipitation, and diet diversity,” said Ana Loboguerrero, an economic policy expert who was not involved with the study.