The EuroMOMO mortality-monitoring network, supported by the ECDC and WHO, recorded more than 10,000 excess deaths across European countries during the period, the paper said.

Excess mortality counts deaths above the seasonal norm and is the key gauge of heatwave tolls.

Heat deaths often present as worsened cardiovascular and respiratory disease, easily missed in statistics yet lethal for the elderly and chronically ill.

European governments are bolstering cooling support and heat-alert systems, but climate change keeps raising heatwave frequency and intensity.

For Korea, China and Japan sweltering near 40 degrees this summer, the lesson lands close to home, underscoring protections for the vulnerable.