Extreme heat killed more than 47,000 people across Europe last summer, marking the continent’s second deadliest year on record for heat-related mortality after 2022.

The figure was estimated by scientists at the Barcelona Institute for Global Health in a study published by Nature Medicine on Monday.

The study also found that more women died of heat-related illnesses than men, with southern Europe, which has been scorched by record temperatures and rising wildfires due to climate crisis, hit the worst.

Scientists analysed mortality data from 823 regions in 35 European countries and temperature records to arrive at the estimate.

Greece recorded the highest mortality rate at 393 deaths per million, followed by Bulgaria, Italy and Spain. More than 40 per cent of southern Europe was affected by extreme heat in July.

The total death toll for the year reached 47,690, with 57 per cent of the deaths occurring during two major heatwaves in mid-July and late August.

This was the second-highest heat-related death toll in Europe after 2022, when heatwaves contributed to more than 60,000 deaths.

The study’s authors pointed out that the actual number of heat-related deaths in 2023 could be higher than reported. Due to the lack of daily mortality data, researchers had to rely on weekly death counts, which may have led to underestimates. They suggested that the true death toll was closer to 58,000.

Women were more vulnerable to heat-related deaths, with a mortality rate 55 per cent higher than men.

The elderly were also at extreme risk, with those over 80 experiencing a 768 per cent higher death rate compared to those aged 65-79.

While the study noted a decrease in heat vulnerability over the years, thanks to improved public health measures and socioeconomic progress, it warned of the limits of adaptation.

“Our results show how there have been societal adaptation processes to high temperatures during the present century, which have dramatically reduced the heat-related vulnerability and mortality burden of recent summers, especially among the elderly,” said Elisa Gallo, the study’s lead author.

Researchers estimated that without these societal changes, the death toll could have been 80 per cent higher, exceeding 85,000. However, they cautioned that human physiology and societal structures have inherent limits, meaning further adaptation may not be enough to protect against increasingly high temperatures.

As Europe continues to warm at twice the global average, the study highlighted the urgent need for both adaptation and mitigation strategies.

“We need to take into account that inherent limits in human physiology and societal structure are likely to set a bound to the potential for further adaptation in the future,” said Joan Ballester Claramunt, principal investigator of the study.

“There is an urgent need to implement strategies aimed at further reducing the mortality burden of the coming warmer summers.”

The year 2023 was the hottest on record. In fact, research estimating past temperatures before the records began found that it was the hottest in the northern hemisphere over the past 2,000 years.

Last year’s extreme temperatures continued until the middle of this year, with July breaking the record streak with a slight drop in mercury.

Scientists from the European climate change agency Copernicus said the continent saw a record number of days with “extreme heat stress” when temperatures felt hotter than 45C due to humidity even if mercury was lower.

Europe is the fastest-warming continent in the world.

While the global mean near-surface temperature between 2013 and 2022 was 1.13 to 1.17C warmer than the pre-industrial level, making it the warmest decade on record, European land temperature increased by 2.04 to 2.10C.