By Abbas Nazil
Climate change is exposing 583 million children under the age of 10 to at least 20 additional heat-stress days every year, with South Asia, Southeast Asia and West Africa recording some of the highest levels of childhood exposure to dangerous humid heat, a new study has found.
The study, published in Science Advances, combined climate models with demographic data to examine how human-caused warming has affected exposure to hot and humid conditions across different age groups and regions.
Researchers found that children under 10 are currently experiencing more additional climate-change-driven heat-stress days than any other age group, raising concerns about the growing impact of extreme heat on children in vulnerable communities.
The research found that 44% of children under 10 globally, equivalent to about 583 million people, are already exposed to at least 20 additional heat-stress days annually as a result of human-caused climate change.
In comparison, about 190 million people aged between 60 and 69, representing 30% of that age group, experience at least 20 additional attributable heat-stress days each year.
The researchers attributed the particularly high exposure among children partly to population structure, noting that there are about 1.3 billion children under 10 globally compared with approximately 600 million people aged between 60 and 69.
They also found that many countries in Africa and Asia have rapidly growing populations with a relatively large proportion of young children, while many cooler countries in the Northern Hemisphere have older populations.
The study measured heat stress using indoor wet-bulb globe temperature, which accounts for both temperature and humidity.
A heat-stress day was defined as a day when wet-bulb globe temperature exceeded 28°C, the threshold identified for moderate heat stress.
Researchers compared conditions under the present-day climate, represented by 2023 when human activity had contributed about 1.3°C of warming, with a simulated pre-industrial climate without human-caused warming.
The difference between the two scenarios was used to estimate the number of additional heat-stress days attributable to climate change.
The study found that countries located in the tropics experience the largest increases in attributable heat-stress days.
For example, Côte d’Ivoire currently experiences an average of 112 heat-stress days annually, with about half attributed to human-caused climate change.
Germany, by comparison, records an average of just 0.1 heat-stress days annually under the study’s measure, although researchers cautioned that the analysis focuses specifically on humid heat and does not capture some local factors such as the urban heat-island effect.
The researchers also examined how exposure could change under future warming scenarios of 1.5°C and 2°C.
They found that 11% of children under 10 currently experience at least 100 additional heat-stress days each year due to climate change.
That proportion is projected to rise to 13% in a 1.5°C warmer world and 23% under 2°C of warming.
Among people aged 60 to 69, the corresponding figures are currently 6%, rising to 9% at 1.5°C warming and 17% at 2°C warming.
The findings indicate that greater warming will expose more people to heat stress, with younger age groups generally facing the greatest increase in exposure.
However, researchers and outside experts cautioned against viewing children’s greater exposure as evidence that older people face little risk.
Qinqin Kong, a researcher at Stanford University who was not involved in the study, said older adults can also be highly vulnerable because some live alone, have limited mobility or face difficulties accessing cooling and emergency assistance during extreme heat.
The study’s lead author, Rosa Pietroiusti, said the research could strengthen discussions around climate justice, children’s rights and intergenerational equity.
She noted that children in developing countries facing some of the greatest increases in heat-stress exposure have generally contributed the least to historical greenhouse gas emissions.
Researchers also called for closer cooperation between climate scientists and health experts to develop heat-stress indicators that better reflect the specific health and educational impacts extreme heat can have on children.
The study further highlights potential gaps in global heatwave reporting, particularly in Africa, where inadequate news coverage and formal reporting can result in extreme heat events being underrepresented in disaster databases.
Experts said climate-data-based research could help fill some of these gaps and provide stronger evidence for protecting populations facing increasing heat exposure.
As global temperatures continue to rise, the researchers warn that children in low-latitude regions are likely to remain among those most exposed to dangerous humid heat, reinforcing the need for stronger climate adaptation, heat-health planning and protection for vulnerable populations.
