Climate Change Increases Heat Stress Risks for 580 Million Children Annually

More than 40% of children under 10 worldwide are already experiencing at least 20 extra days of dangerous heat stress annually due to climate change, according to a new study published in Science Advances. The research, led by scientists from institutions including Vrije Universiteit Brussel, combines climate models with demographic data to assess how rising temperatures and humidity disproportionately affect the youngest populations.

The study reveals that south Asia, southeast Asia, and west Africa are the regions where children face the highest exposure to humid heat linked to climate change. These areas combine rapidly growing populations with large proportions of young children, making them particularly vulnerable. The findings underscore a growing climate justice issue, as children in developing nations have contributed least to global greenhouse gas emissions yet bear the brunt of the consequences.

Researchers used wet-bulb globe temperature—a measure combining heat and humidity—to identify heat-stress days, defined as days exceeding 28°C wet-bulb temperature, a threshold associated with moderate heat stress. Comparing present-day conditions (based on 2023 climate data with 1.3°C warming) to a pre-industrial baseline, they calculated the number of extra heat-stress days attributable to human-caused climate change.

Globally, 583 million children under 10—44% of all children in this age group—are now experiencing at least 20 additional heat-stress days each year due to climate change. By comparison, only 190 million people aged 60–69 (30% of that cohort) face the same level of exposure. The disparity arises because younger populations are more numerous in tropical regions, where heat and humidity are most intense.

Lead author Rosa Pietroiusti of Vrije Universiteit Brussel notes that the study specifically examines humid heat, which is less commonly felt in cooler regions like Europe. She emphasizes that the data does not fully capture localized urban heat effects, meaning local experiences of heat stress may be even higher than reported.

Looking ahead, the study projects that under 1.5°C and 2°C warming scenarios, the percentage of children under 10 experiencing over 100 extra heat-stress days annually will rise from 11% today to 13% and 23%, respectively. For adults aged 60–69, the figures increase more gradually, from 6% today to 9% and 17% under the same scenarios.

The research highlights that extreme heat poses greater risks to children, older adults, and individuals with pre-existing health conditions due to their reduced ability to regulate body temperature. The findings call for urgent climate action and targeted adaptation measures to protect the most vulnerable populations, particularly in low-latitude countries where heat exposure is most severe.

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