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What Happened with Mortality Due to Temperature during the COVID-19 Pandemic in Europe?

15.7.2025
Covid calor Edu Bayer Ajtm Bcn
Photo: Edu Bayer / Barcelona City Council

New data show a rise in heat-related deaths during the COVID-19 pandemic in Europe and expose inequalities in climate adaptation.

Global warming is raising average temperatures, leading to a decline in cold-related deaths and an increase in heat-related deaths. This trend is expected to keep worsening if no strong adaptation and mitigation strategies are put in place. A recent study estimated that in 2023, heat-related deaths in Europe would have been 80% higher in the absence of historical adaptation efforts.

But here's the catch: these estimations do not consider global and regional events, such as the COVID-19 pandemic, which significantly impacted public health and the broader socio-economic landscape. Such disease caused over 7 million deaths and 777 million cases worldwide, thus impacting health systems, economies, and societal structures.

Missing a huge part of the picture

Given the clear intersection between climate-related and pandemic-related health risks, you would expect more studies to explore what happened with the temperature-related vulnerability during the COVID-19 pandemic. Surprisingly, this hasn’t been the case. A key challenge explaining this gap has been the lack of reliable data on COVID-19 deaths during the early months of the pandemic due to underreporting, as well as the complexity of analysing such mortality disruptions. As a result, many previous studies either excluded data after 2020 or directly removed the COVID-19 deaths from the total mortality counts, with the limitations that this entails.

Many studies either excluded data after 2020 or directly removed the COVID-19 deaths from the total mortality counts, with the limitations that this entails

Nonetheless, researchers can not keep omitting post-2020 data. Someone had to look into this, and at ISGlobal, we have been working on just that

Photo: Isaac Planella / Barcelona City Council.
 

In our latest study, we developed an innovative methodology to adjust for COVID-19 deaths, allowing us to take a more accurate assessment of temperature-related mortality. We believe this approach highlights the need for including pandemic data and adjusting for COVID-19 deaths in future research; ignoring it means missing a huge part of the picture.

For instance, to give you an example, other articles predicting pandemic and post-pandemic years, such as the one from Ballester et al, 2023, which estimated a total of 61,672 heat-related deaths during the summer of 2022, used pre-pandemic fittings that no longer capture current vulnerabilities. When comparing this number with the updated methodology, the heat-related mortality in that same period was 14.42% higher, reaching approximately 71,400 deaths.

Who is adapting better in Europe?

However, this wasn’t all! We also explored the change in the mortality risk over time to assess whether the European population has adapted to heat and cold before and after the onset of the COVID-19 pandemic. What we found was concerning: there has been a maladaptation to heat in southern and western Europe, meaning the population in those regions is becoming more vulnerable to high temperatures. On the other hand, we observed some adaptation to cold in northern, eastern, and western Europe.

There has been a maladaptation to heat in southern and western Europe, meaning the population in those regions is becoming more vulnerable to high temperatures. On the other hand, we observed some adaptation to cold in northern, eastern, and western Europe

This paints a clear picture of how adaptation isn’t happening evenly across the continent, thus highlighting the regional differences in temperature adaptation and emphasising the urgent need to strengthen heat-related adaptation and mitigation measures in Europe. These may include early warning systems, public health campaigns and targeted science communication efforts. Most importantly, our results suggest that these adaptation strategies should be targeted to the needs of the most vulnerable regions, particularly in southern Europe, where countries like Spain or Italy are facing increasing heat-related risks.

More effective and responsive temperature-related adaptation plans

Ultimately, I believe the methodology we developed in our study better reflects the current vulnerability, shaped not only by climatic conditions but also by societal responses to crises like the COVID-19 pandemic. This approach offers robust and context-sensitive evidence for policy-makers and institutions to support the design and implementation of more effective and responsive temperature-related adaptation plans.

Adaptation strategies should be targeted to the needs of the most vulnerable regions, particularly in southern Europe, where countries like Spain or Italy are facing increasing heat-related risks

With the hope of supporting well-informed and inclusive action from stakeholders, future adaptation strategies will not only need to be responsive but also equitable to the challenges of our time.

Reference

Paniello-Castillo B, Quijal-Zamorano M, Gallo E, Basagaña X, Ballester J. Regional changes in temperature-related mortality before and during the COVID-19 pandemic: a continental modelling analysis in 805 European regions. Environmental Research 278, 121697 (2025).