The World Health Organization said Sunday that more than 1,300 excess deaths recorded across Europe since June 21 have been linked to the extreme heatwave that has sent temperatures soaring from the upper 90s to low 100s Fahrenheit across the continent since at least mid-June.

WHO Director-General Tedros Adhanom Ghebreyesus called heat stress the “silent killer” in a statement and noted that European infrastructure was not designed for such conditions. “European homes, workplaces and schools were not built for these temperatures,” he said. Tedros urged countries to “implement heat health action plans” as part of broader efforts to protect citizens against climate change.

Europe is the fastest-warming continent on Earth, heating at twice the global average, Tedros said, adding that 150 million people are currently living under extreme heat that has shuttered schools, buckled power grids and killed hundreds. “Driven by climate change and global warming, the phenomenon of the ‘once-in-a-generation’ heatwave is now occurring nearly annual,” he said. “We were warned.”

France’s Health Ministry reported about 1,000 additional deaths since Wednesday compared to previous months, with the increases most pronounced in regions under a red alert for high temperatures, including Normandy and Pays de la Loire. About 85% of the fatalities were in people 65 and older, and the ministry recorded a roughly 40% increase in deaths occurring at home. “This observation serves as a reminder of the need for measures of solidarity toward people who are isolated or experiencing profound loneliness, including in highly urbanized areas,” the ministry said.

The heatwave has broken records in Germany, Belgium and the Netherlands, prompting officials to cancel outdoor events and issue warnings. The event follows a rapid attribution study earlier this month that found the heat gripping Europe would have been virtually impossible without human-caused climate change.

U.N. Climate Change Executive Secretary Simon Stiell said in an online statement that “Europe’s savage heatwave has the fingerprints of the climate crisis all over it.” He added: “Until humanity stops burning coal, oil and gas, extreme heat will keep getting worse. The solutions are clear: a faster shift to renewables, protecting forests and boosting climate resilience.”