Southern France was slammed by a heat wave so intense in June that Celine Imart was forced to harvest rapeseed in the middle of the night to avoid searing hot tractors from sparking fires in her fields. Farmers elsewhere had reported crackling dry crops spontaneously catching fire after coming into contact with the heat from harvesters.

Record-high temperatures had brought the earliest-ever heat wave across large sections of France, as well as to Spain and parts of Italy. For Imart, a 39-year-old sixth-generation farmer near Toulouse, the dry weather so early in the year meant the harvest of durum wheat, the variety used to make pasta, was finished two weeks earlier than usual and yielded 30% below normal.

"From one day to another, it passed from too much rain to too dry,” Imart said, adding that the phenomenon accelerated the development of crops. "We see it in our farm — the time of the harvest is earlier and earlier each year, advancing all the time.”