The summer of 2023 was one for the record books — both in temperature highs and the devastating human toll it exacted. It was the hottest year on record and a testament to what’s to come with global heating. According to recent research, over 47,000 heat-related deaths may have occurred in Europe in the year 2023. However, we are not helpless: without climate adaptation, the figure would have increased by around 80%.
Climate heating is killing people in more than one way. It can worsen air quality by increasing the prevalence of pollutants and allergens, leading to respiratory and cardiovascular problems. Indirectly, climate heating can contribute to food and water scarcity, drive the spread of infectious diseases, and increase the frequency and severity of natural disasters such as hurricanes, floods, and wildfires. However, the most direct way is through extreme weather events like heatwaves.
Heatwaves strain the human body’s ability to regulate temperature, leading to heat-related illnesses such as heatstroke, dehydration, and cardiovascular problems. Vulnerable populations, including the elderly, those with preexisting health conditions, and people in regions with inadequate infrastructure or healthcare, are particularly at risk. As global temperatures rise, these extreme heat events become more frequent and severe. Estimating how many people are killed by such events is not straightforward, however.
Researchers led by Elisa Gallo from the University of Padova, Italy used mortality records representing 96 million counts of deaths from the European Statistical Office (Eurostat). They assessed the heat-related mortality burden in 2023 across 35 European countries, focusing only on direct effects.
The findings reveal a stark reality: southern Europe was hit hardest, with countries like Greece, Bulgaria, and Italy experiencing the highest mortality rates per million people. Greece alone reported 393 heat-related deaths per million people, highlighting the country’s vulnerability.
However, it’s not all bad news.
Adaptation matters
the year 2023 for the overall population. Image credits: Nature / Gallo et al (2024).
Despite the grim statistics, the study also emphasizes the significant impact of adaptation measures implemented since the early 2000s. The researchers estimate that without these measures, the heat-related mortality burden in 2023 could have been 80% higher. This translates to around over 85,000 deaths, so a great deal of harm was avoided. This underscores the effectiveness of public health strategies, infrastructural improvements, and societal changes in reducing the human cost of extreme heat.
In this context, adaptation refers to a broad range of societal and behavioral changes that reduce vulnerability to heat. These include improved building designs, widespread use of air conditioning, planting of trees, public health campaigns, and early warning systems. The research found that the most significant reductions in mortality were among the elderly, particularly those over 80 years old, who are most susceptible to the adverse effects of extreme heat.
Yet, while some of the vulnerable groups were intuitive, some findings were surprising.
The demographics of vulnerability
Age is a critical factor. The elderly, particularly those over 80, were far more likely to succumb to heat-related illnesses. The study estimates that for this age group, the mortality rate was over 1,100 deaths per million — a staggering figure that underscores the need for targeted adaptation strategies.
However, one of the most striking aspects of the research is its detailed breakdown of heat-related mortality across different demographics. Women, for instance, were found to be significantly more vulnerable than men, with a mortality rate 55% higher. This disparity is likely due to a combination of biological, behavioral, and social factors, though the exact reasons remain unclear.
By knowing which groups are most vulnerable, researchers can design careful interventions that save more lives. However, while adaptation has saved lives, it is not a panacea.
Climate heating concerns us all
The state of climate heating is increasingly alarming. Earth’s temperature has risen by an average of 0.11° Fahrenheit (0.06° Celsius) per decade since 1850, or about 2° F (1° C) in total. This relentless warning is set to continue as we also continue to pump out greenhouse gas emissions. Extreme weather events such as heatwaves, wildfires, and intense storms are set to become more common and even more intense.
As we (hopefully) work to reduce our emissions, we must also develop strategies to cope with the escalating threat of climate change. This includes not only enhancing existing adaptation measures but also investing in new technologies, infrastructure, and public health initiatives that can better protect populations from extreme heat.
The world is on track to exceed the critical 1.5°C warming threshold set by the Paris Agreement, which would lead to catastrophic impacts on global health, food security, and biodiversity. Furthermore, many inhabited places (especially cities) have become much hotter than the global average due to the heat island effect.
Although this research focused on Europe, similar trends are happening elsewhere in the world — possibly even worse.
As global temperatures continue to rise, so too must our efforts to adapt and mitigate the impacts of climate change. The lives of millions depend on it.
The study “Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health” was published in Nature Medicine.
