Here is a strange detail to sit with. An 18-year-old who had volunteered to fight fires may have been the person who started one — at least, that is what French prosecutors suspect. The young man was placed under formal investigation after he reportedly admitted to igniting twigs with a lighter and petrol in the Fontainebleau forest, south of Paris, before withdrawing that confession. A second 18-year-old has also been formally investigated.

The blaze has now scorched more than 2,000 hectares — roughly 5,000 acres — of one of France's most celebrated landscapes, forced around 1,000 people from their homes, and partially shut the country's main north-south motorway. What makes this story bigger than one forest, however, is the world surrounding it. President Emmanuel Macron visited the scorched trees on Thursday and offered a sobering comparison: France has not seen so many fires since the Second World War. Nearly 11,000 fires have been recorded across the country since January alone.

The Palace and Park of Fontainebleau — a UNESCO World Heritage Site since 1981 — now has roughly 10% of its ancient woodland reduced to ash. Macron promised that arsonists would face no leniency, though the investigation is still ongoing. The deeper story, though, sits above any individual lighter or courtroom. According to the Copernicus climate service, Europe is warming twice as fast as the global average, making it the fastest-heating continent on Earth.