Young children exposed to extreme heat show reduced literacy and numeracy skills, according to a new study using UNICEF data from six countries. Temperatures above 30°C hinder developmental milestones from age three to four. The findings highlight how climate change exacerbates vulnerabilities in early human growth.
A study published in the Journal of Child Psychology and Psychiatry reveals that extreme heat significantly affects children's early learning abilities. Researchers, led by Jorge Cuartas at New York University, analyzed data from 19,600 children surveyed by UNICEF in Georgia, the Gambia, Madagascar, Malawi, Sierra Leone, and the State of Palestine. The Early Childhood Development Index assessed skills such as naming letters, reading simple words, and recognizing numbers from 1 to 10.
The team compared these results with climate records, accounting for factors like poverty, maternal education, and local baseline temperatures. Children experiencing average monthly maximums of 32°C (90°F) or higher were 2.8 to 12.2 percent less likely to be developmentally on track than those in areas up to 26°C (79°F). Even 30°C (86°F) began to impair literacy and numeracy, with lesser effects on social, emotional, and physical development.
"This is the first time that is shown in the literature that excessive heat not only affects physical health, but also these developmental skills," says Cuartas. He notes that prenatal exposure also matters: temperatures of 33°C (91°F) in the first trimester reduced on-track development by 5.6 percent. Early deficits can compound, as a child knowing fewer numbers might struggle with arithmetic later.
The impact is amplified among poorer, urban households without water access. "Climate change and excessive heat act as threat multipliers [on] children who are already facing disadvantages," Cuartas adds. Heat stress already causes nearly half a million weather-related deaths annually, including 2,300 from a recent European heatwave.
Julia Pescarini at the London School of Hygiene & Tropical Medicine cautions that the study might not fully control for issues like violence or instability. She calls for more research into mechanisms, such as lack of air conditioning or parental stress, to inform adaptation strategies.