More than 47,000 individuals succumbed to high temperatures in Europe in 2023, marking it as the warmest year globally on record and the second hottest in Europe.
In 2023, more than 47,000 people in Europe died due to extreme heat, making it the hottest year ever recorded worldwide and the second hottest in Europe. This estimate comes from a study led by the Barcelona Institute for Global Health (ISGlobal), which is backed by the “la Caixa” Foundation, and was published in Nature Medicine. The research indicates that European societies have progressively become less vulnerable to heat over the current century, and suggests that without these adaptations, the mortality rate related to heat in the past year would have been 80% higher.
The study utilized the same methodology as a previous paper published in Nature Medicine last year, which indicated that heat resulted in over 60,000 deaths during the summer of 2022, marking the highest heat-related mortality impact in the last ten years. The researchers analyzed temperature and death data from 823 regions in 35 European countries from 2015 to 2019 to develop epidemiological models that estimated heat-related mortality for the whole of 2023 across Europe.
Unlike the summer of 2022, which experienced prolonged extreme temperatures from mid-July to mid-August, 2023 did not show significant temperature anomalies during those weeks. However, two separate heat waves in mid-July and late August accounted for more than 57% of the overall estimated deaths, totaling over 27,000 fatalities.
Southern European countries most impacted
The findings reveal an estimated total of 47,690 deaths in 2023 across the 35 countries, with 47,312 of those occurring during the hottest months (from May 29 to October 1). When considering population size, the countries most affected by heat-related mortality were primarily in southern Europe: Greece (393 deaths per million), Bulgaria (229 deaths per million), Italy (209 deaths per million), Spain (175 deaths per million), Cyprus (167 deaths per million), and Portugal (136 deaths per million).
Increased vulnerability among women and those over 80
The data corroborate previous findings indicating that both women and older individuals exhibit increased vulnerability to heat. Specifically, the heat-related mortality rate was 55% higher for women compared to men, and 768% higher for individuals over 80 years old than for those between 65 and 79 years.
Potential underestimation of the heat-related mortality toll
The study’s authors warn that these figures may not fully represent the actual heat-related mortality toll. Due to the lack of daily and consistent mortality data for 2023, the researchers relied on weekly death counts from Eurostat. A recent paper published in Lancet Regional Health — Europe by the same authors pointed out that weekly data can lead to an undercounting of heat-related deaths and described a method to correct this oversight. Given this context, they estimate that the actual number of heat-related deaths in 2023 could be around 58,000 across the studied countries, although a more accurate figure could be determined if better mortality databases were available to researchers.
Counteracting heat’s impact through adaptation
One key goal of the study was to evaluate whether Europe’s vulnerability to heat has decreased, reflecting a process of adaptation to rising temperatures. To assess this, researchers applied a similar model to temperature and mortality data from various years (2000–2004, 2005–2009, 2010–2014, and 2015–2019) and projected what the death toll would have been in those periods if faced with 2023’s temperatures.
Using this approach, it was estimated that had the temperatures of 2023 occurred in the 2000-2004 timeframe, the heat-related mortality would have surpassed 85,000 deaths, signifying an 80% increase compared to the vulnerability seen in 2015-2019. For individuals over 80 years of age, the expected death toll would have more than doubled, increasing from 1,102 to over 2,200 due to heat.
“Our findings illustrate that societal adaptations to high temperatures in this century have significantly lessened heat-related vulnerability and mortality, particularly among older adults,” notes Elisa Gallo, a researcher at ISGlobal and the study’s lead author.
“Since 2000, we have observed that the minimum mortality temperature—the temperature with the lowest death risk—has gradually increased across Europe, from 15ºC in 2000-2004 to 17.7ºC in 2015-2019. This trend suggests that our heat vulnerability has decreased, likely due to advances in socio-economic conditions, improved personal behaviors, and public health initiatives like heat prevention plans initiated after the extremely hot summer of 2003,” adds Elisa Gallo.
Exceeding physiological limits of adaptation
“In 2023, close to half of the days surpassed the 1.5°C threshold established by the Paris Agreement, with Europe warming at a pace twice that of the global average. Climate predictions indicate that this 1.5°C limit might be breached before 2027, drastically limiting our time to respond,” cautions Joan Ballester Claramunt, Principal Investigator of the European Research Council (ERC) Consolidator Grant EARLY-ADAPT.
“It is essential to recognize that there are inherent limits within human physiology and societal structures that may restrict our future adaptability. There is an urgent need for strategies that further decrease mortality rates during warmer summers, alongside enhanced monitoring of climate change impacts on at-risk populations. These adaptation efforts should go hand in hand with mitigation actions taken by governments and the general public to prevent reaching critical temperature thresholds,” he emphasizes.
Forecaster.health, a tool for assessing mortality risk by demographic factors
Recently, the research team introduced Forecaster.health, a publicly accessible online tool that forecasts mortality risks linked to extreme cold and heat by sex and age across 580 regions in 31 European nations. This early warning system goes beyond basic weather data, incorporating epidemiological models to provide a more accurate assessment of health risks for various demographic groups. Forecaster.health is free to use and offers forecasts that extend up to 15 days ahead.
