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Excess mortality attributable to the 2025 Iberian Peninsula blackout
Garyfallos Konstantinoudis1, Julien Riou2
1Grantham Institute for Climate Change and the Environment, Imperial College London, London, UK. g.konstantinoudis@imperial.ac.uk.
Nature Communications
|July 20, 2026
Summary
The 2025 Iberian blackout increased mortality in Spain, particularly among elderly women, but not in Portugal. This highlights the underestimated health burden of power outages and the need for climate change preparedness.
Area of Science:
- Public Health
- Environmental Health
- Epidemiology
Background:
- Power outages pose significant health risks, ranging from direct impacts like medical equipment failure to indirect consequences such as disrupted healthcare services.
- The health burden of large-scale blackouts, especially in the context of climate change, requires further investigation.
Purpose of the Study:
- To assess the association between the 2025 Iberian blackout and mortality in Spain and Portugal.
- To identify specific demographic groups and temporal patterns of excess mortality following the event.
Main Methods:
- Utilized mortality data from Spain and Portugal.
- Employed statistical analysis to compare mortality rates before, during, and after the blackout event.
- Investigated demographic factors, including age and sex, and regional variations in mortality.
Main Results:
- The 2025 Iberian blackout was associated with increased mortality in Spain, but not in Portugal.
- Excess mortality in Spain was observed in the two days following the event (+167 deaths), particularly among women aged 85+.
- Regional differences in mortality impact were noted, though their causes remain uncertain.
Conclusions:
- Large-scale power outages represent a significant, underestimated public health threat.
- Improved preparedness strategies are crucial for mitigating the health impacts of blackouts, especially considering a changing climate.
- Further research is needed to understand regional variations and underlying drivers of differential mortality impacts.
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