Er Hu works in an office tower in Chongqing most days. But when forest fires erupted in the south-western Chinese city as it faced the country’s worst drought for decades, the 31-year-old visa consultant grabbed his motorbike and rode to the outskirts to help transport supplies to fight the blazes.

“There were 1,000-2,000 firefighters on the mountains but lots of motorcycle volunteers,” he said, adding that cars struggled to navigate the muddy paths.

Sichuan province started to restore power for industrial users from Sunday, but the impact on the broader economy from the heatwave, which caused temperatures in Chongqing to rise 7C higher than the average level over the past decade, has been severe. Widespread power shortages in the south-west paralysed industry in a crisis that scientists said was probably caused by climate change.