An unusually intense and early summer heat wave across Europe is believed to have caused more than 10,000 excess deaths, with health experts warning that the true toll may be even higher as heat-related fatalities are often not officially recorded.
Preliminary figures from mortality monitoring agencies across Europe show a sharp rise in excess mortality — the number of deaths above what would normally be expected — during the final week of June, when record-breaking temperatures swept across much of the continent.
Researchers say many heat-related deaths are never directly attributed to extreme temperatures because victims often die from conditions such as heart attacks or respiratory illnesses that are worsened by prolonged heat exposure.
The findings point to one of Europe's deadliest early-summer heat events in recent years, although the devastating 2003 heat wave, which claimed an estimated 70,000 lives, remains the continent's worst on record.
According to EuroMOMO, a European mortality monitoring network covering two dozen countries, an estimated 14,260 excess deaths were recorded during the week ending June 28. More than 12,000 of those deaths involved people aged 65 or older. The network reported that France, Belgium and Germany experienced the highest levels of excess mortality during the period.
Lasse Vestergaard of Denmark's Statens Serum Institut, which coordinates EuroMOMO, said the heat wave was the most likely explanation for the unusually high number of deaths, noting there was no other significant event that could account for the spike.
Several countries have also released their own estimates of heat-related deaths.
Germany recorded the highest national toll, with the Robert Koch Institute attributing 6,830 deaths to extreme heat through early July, including 6,470 among people aged 65 and above. The country experienced record temperatures of 41.7 degrees Celsius on June 28.
In the United Kingdom, the Met Office estimated that around 2,700 people died from heat-related causes during heat waves in May and June across England and Wales, including approximately 2,200 deaths during the late-June heat wave.
France's public health authority reported at least 2,000 more deaths during the week of June 22-28 compared with the previous week, as much of the country endured temperatures above 40 degrees Celsius.
Spain's Carlos III Health Institute estimated that 937 deaths in June were linked to excessive heat after the country experienced its second-hottest June on record.
Belgium reported 1,747 excess deaths during the heat wave that lasted from June 18 to July 1, with health authorities describing the event as exceptionally widespread.
In the Netherlands, public health officials estimated 480 more deaths than expected during the June heat wave, particularly in the eastern and southern parts of the country, where temperatures were highest.
Scientists say climate change, driven largely by the continued use of fossil fuels, is increasing both the frequency and intensity of heat waves, making such deadly events more common across Europe. They also warn that older adults and people with underlying health conditions remain especially vulnerable during prolonged periods of extreme heat.