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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, especially 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:
- Environmental Health
- Public Health
- Epidemiology
Background:
- Widespread power outages, or blackouts, can have significant health consequences.
- These impacts range from direct effects like medical equipment failure to indirect consequences such as disrupted healthcare services.
Purpose of the Study:
- To investigate the association between the 2025 Iberian blackout and all-cause mortality in Spain and Portugal.
- To identify specific demographic groups and temporal patterns of mortality following the event.
Main Methods:
- Ecological study design analyzing mortality data from Spain and Portugal.
- Time-series analysis comparing observed mortality during and after the blackout period to expected levels.
Main Results:
- The 2025 Iberian blackout was associated with a significant increase in mortality in Spain (+167 deaths, +2.4% relative increase) in the two days following the event.
- Increased mortality in Spain was particularly notable among women aged 85 and older.
- No significant increase in mortality was observed in Portugal, nor on the day of the blackout in either country.
Conclusions:
- The study demonstrates a clear association between the Iberian blackout and increased mortality in Spain, underscoring the health risks posed by power outages.
- Findings suggest that the health burden of blackouts is underestimated and varies geographically, potentially due to differences in outage impact or local resilience.
- Improved public health preparedness for widespread power outages is crucial, especially in the context of a changing climate.
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