A record 15 national heat records have been broken since the start of this year, an influential climate historian has told the Guardian, as weather extremes grow more frequent and climate breakdown intensifies.

An additional 130 monthly national temperature records have also been broken, along with tens of thousands of local highs registered at monitoring stations from the Arctic to the South Pacific, according to Maximiliano Herrera, who keeps an archive of extreme events.

He said the unprecedented number of records in the first six months was astonishing. “This amount of extreme heat events is beyond anything ever seen or even thought possible before,” he said. “The months from February 2024 to July 2024 have been the most record-breaking for every statistic.”

This is alarming because last year’s extreme heat could be largely attributed to a combination of man-made global heating – caused by burning gas, oil, coal and trees – and a natural El Niño phenomenon, a warming of the tropical Pacific Ocean surface that is associated with higher temperatures in many parts of the world. The El Niño has been fading since February of this year, but this has brought little relief.