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A new report from the United Nations Children’s Fund (UNICEF) has used climate data from the EU’s Copernicus Climate Change Service (C3S), implemented by ECMWF, to build the most detailed global picture to date of climate hazards affecting children worldwide.
The Children’s Climate Risk Report (2026) incorporates the latest precision data from the new UNICEF Global Child Hazard Database, which uses ERA5 climate reanalysis data, to assess where children are exposed to multiple, overlapping climate hazards including drought, floods, storms, wildfires, and extreme heat.
By combining climate hazard exposure with information on children’s vulnerability – including access to healthcare, water, nutrition, education, and social services – the report provides policymakers with a more detailed understanding of where climate-related risks are most severe and where interventions may be most urgently needed.
Delphine Deryng, ECMWF’s Partnership and User Engagement Specialist, said: “This initiative is an important example of how state-of-the-art ERA5 reanalysis data can be applied to strengthen climate risk assessment. By deriving child-specific heat stress indicators, it makes climate risks more robust and meaningful, providing crucial evidence for better-informed decision-making.”
Tracking heat hazards with ERA5 data
The use of ERA5 is particularly important for heat-related risks, where local conditions determine whether temperatures become dangerous for children and communities.
To analyse the specific threats of extreme heat and heatwaves in the study, the scientific team at UNICEF used daily average temperatures from the ERA5 reanalysis dataset, which provides a continuous spatially explicit global climate record from 1940 to the present.
The report defines a heatwave as a period of three or more consecutive days in the top 10% of the local 15-day average. The scientific team measured three heatwave dimensions: annual frequency, total duration, and severity, defined as degrees Celsius above the local average. These were assessed alongside extremely hot days exceeding 35°C.
Using the ERA5-Land dataset, detailed temperature patterns were analysed globally at around 10 km resolution to identify locally relevant heat extremes based on historical conditions. Because what constitutes a severe heatwave depends on what communities are accustomed to, this approach ensures that climate risks are assessed in a locally meaningful way.
To better represent small island developing states (SIDS), the study also uses the coarser 25 km ERA5 dataset, which includes ocean areas. While less detailed, this broader coverage is essential for capturing small island contexts. This reflects ongoing discussions with UNICEF to ensure these particularly vulnerable communities are more accurately represented in climate risk assessments.
To calculate child exposure, heatwave hotspots (where heatwave indicators exceeded long-term average) were overlaid with a high-resolution global child population map. The results were then mapped onto national and regional boundaries to pinpoint exactly how many children are exposed within each country, for four indicators: heatwave frequency, duration, severity, and extreme temperature.
Climate data informing global resilience planning
The report demonstrates how high-quality climate datasets, such as ERA5, enable organisations to assess where and how climate hazards affect vulnerable populations, and to use that evidence to support more targeted resilience planning and decision-making.