Quantifying the human-induced climate change impact on heat-related mortality events in Europe with Extreme Event Attribution Methods

Numerous Extreme Event Attribution (EEA) studies have consistently shown that human-induced climate change has increased the likelihood of extreme heat events. The increasing relevance of these studies in the context of climate litigation underscores the demand for the quantification of climate change impacts. Heat, as the primary contributor to weather-related mortality on the European continent, has caused more than 61,000 heat-related deaths in Europe during the 2022 summer. We carry out this proof-of-concept study in which we apply Extreme Event Attribution methods combined with epidemiological models to quantify how anthropogenic warming has influenced extreme heat-related mortality events in Europe. In contrast to most health impact studies, we utilize open-access mortality data from Eurostat, which is available in near-real time.

Because of the complex, non-linear relationship between temperature and mortality, we conduct separate Extreme Event Attribution analyses for (i) temperature extremes and (ii) associated heat-related mortality events in 232 distinct administrative regions spanning over 35 European countries. Our findings reveal that the probability of the maximum weekly values observed in 2022 has increased 12-fold [95^th CI 3.51-147.15] for temperature and tripled [95^th CI 1.02-18.63] for mortality compared to the pre-industrial baseline. Notably, we identify significant geographical disparities, e.g. in Spain the mortality risk is even 30 times higher [95^th CI 3.33 – 1218.14] due to anthropogenic warming.

We find a statistically significant trend in 70% [90%] of the regions at the 0.95 [0.90] significance level, and across all age and sex groups, except for women aged 65 years or less, indicating that anthropogenic warming affects almost the entire European population.

This study establishes a foundation for subsequent analyses, not only for heat-related mortality events observed on different temporal and spatial scales but also for enabling an examination of other weather events and associated health impacts. By combining climate sciences and techniques with epidemiology and health data, it is possible to calculate the contribution of climate change to changes in health risks and mortality burdens by sociodemographic categories, such as sex, age, socioeconomic level, or comorbidities, especially in vulnerable groups. This transdisciplinary work has to potential to provide key information for climate-related health lawsuits and opens the door to inter- and transdisciplinary perspectives on how to integrate geoscience and epidemiology insights in litigation.