Attributing heatwave mortality to human-induced climate change in Greece: a case-crossover and attribution analysis for 2000–2019
File(s)
Article in press
Author(s)
Konstantinoudis, Garyfallos
Type
Journal Article
Abstract
Background
Heatwaves increasingly threaten public health in the Mediterranean region, and Greece is among the hardest hit countries. Yet evidence on long-term adaptation, spatial vulnerability, and the contribution of human-induced climate change to heatwave-related mortality in Greece remains limited.
Methods
We analysed 2,144,957 all cause deaths in Greece (2000-2019) in people older than 65 years using a time stratified case crossover design. We derived population weighted daily maximum temperatures at NUTS3 level from ERA5 reanalysis and WorldPop. We applied six heatwave definitions (HD1–HD6) varying by duration (≥2 or ≥3 days) and thresholds (90th, 95th, 99th percentiles).
We fitted Bayesian hierarchical Poisson models to estimate heatwave-mortality associations varying by space and time. We additionally adjusted for relative humidity and national holidays. We then combined these estimates with probabilistic climate attribution methods to quantify the number and proportion of heatwave-related deaths attributable to human induced climate change.
Results
Heatwaves raised mortality consistently, with relative risks from 1.08 (95% CrI (Credible Interval): 1.07–1.09; HD1) to 1.15 (1.12–1.19; HD6). Risks increased with heatwave intensity and duration, with particularly high risks observed among females and older adults. We did not detect a consistent temporal decline in risk or marked spatial heterogeneity. Human induced climate change accounted for 46-80% of heatwave related deaths across definitions. The proportion attributable to climate change rose over time.
Conclusions
Heatwaves already impose a major mortality burden in Greece, with more than half driven by anthropogenic climate change and little evidence of population level adaptation. These findings call for rapid emissions reductions and targeted adaptation, including stronger heat health warning systems and protection of vulnerable groups.
Heatwaves increasingly threaten public health in the Mediterranean region, and Greece is among the hardest hit countries. Yet evidence on long-term adaptation, spatial vulnerability, and the contribution of human-induced climate change to heatwave-related mortality in Greece remains limited.
Methods
We analysed 2,144,957 all cause deaths in Greece (2000-2019) in people older than 65 years using a time stratified case crossover design. We derived population weighted daily maximum temperatures at NUTS3 level from ERA5 reanalysis and WorldPop. We applied six heatwave definitions (HD1–HD6) varying by duration (≥2 or ≥3 days) and thresholds (90th, 95th, 99th percentiles).
We fitted Bayesian hierarchical Poisson models to estimate heatwave-mortality associations varying by space and time. We additionally adjusted for relative humidity and national holidays. We then combined these estimates with probabilistic climate attribution methods to quantify the number and proportion of heatwave-related deaths attributable to human induced climate change.
Results
Heatwaves raised mortality consistently, with relative risks from 1.08 (95% CrI (Credible Interval): 1.07–1.09; HD1) to 1.15 (1.12–1.19; HD6). Risks increased with heatwave intensity and duration, with particularly high risks observed among females and older adults. We did not detect a consistent temporal decline in risk or marked spatial heterogeneity. Human induced climate change accounted for 46-80% of heatwave related deaths across definitions. The proportion attributable to climate change rose over time.
Conclusions
Heatwaves already impose a major mortality burden in Greece, with more than half driven by anthropogenic climate change and little evidence of population level adaptation. These findings call for rapid emissions reductions and targeted adaptation, including stronger heat health warning systems and protection of vulnerable groups.
Date Issued
2026-07-11
Date Acceptance
2026-07-02
Citation
Environmental Health, 2026
ISSN
0340-0131
Publisher
BMC
Journal / Book Title
Environmental Health
Copyright Statement
© The Author(s) 2026. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Publication Status
Published online
Date Publish Online
2026-07-11