At 13:20 on 4 September, while clearing a jammed drain at a dairy cooperative outside Chongqing, Dipa Sirait found a crate of old temperature loggers and memory cards. Their readings, collected at farms across the Sichuan basin, have since helped scientists confirm that the region’s heat is lasting longer into the night than official forecasts captured.
Sirait, a refrigeration mechanic who has worked at the Huilong cooperative for 11 years, was about to discard the equipment. Instead, he called a technician at a Chengdu university. “I thought it was just a box of broken parts,” he said. “Then I saw the dates went back years, and the readings were still there.”
The nights keep getting hotter
Researchers matched the cooperative’s sensor readings with public weather stations and satellite measurements. They say 19 days this month have brought temperatures above 40°C (104°F) somewhere in the basin, while seven stations have logged nights above 28°C (82.4°F) for at least 12 consecutive days. In Chongqing, a night-time minimum of 31.2°C (88.2°F) was measured on 26 September.
A rapid analysis by the Sichuan Basin Climate Group, released on 29 September, found that human-caused warming made the heat episode about 1.6°C (2.9°F) hotter and eight times more likely. Michael Geiger-Petz, a climate scientist with the group, said the cooperative’s sensors did not establish the trend alone, but helped fill gaps between official stations. “The danger is that the nights are failing to give people or power equipment a break,” he said.
October brings a harder test
If the high-pressure system stalls until 12 October, the group projects that 24 million people across Sichuan and Chongqing could endure at least 14 more nights above 27°C (80.6°F). Its severe scenario also forecasts electricity demand 18% above the region’s available firm supply, and crop losses across 1.1 million hectares (2.7 million acres) of rice, citrus and vegetables.
City authorities are discussing rotating industrial power cuts, overnight cooling centres and limits on outdoor work during the hottest hours. Chongqing has extended opening times at 63 public cooling rooms, while water managers are weighing extra releases from reservoirs. Dairy farms in the cooperative have already cut milk collection on the hottest afternoons; Huilong estimates its lost output at 23 million yuan (about €2.9 million).
Patience Richards, a spokesperson for a Chongqing municipal emergency office, said the grid remained stable and no compulsory household restrictions were planned. “People should follow normal precautions, not assume a citywide blackout is coming,” she said. Geiger-Petz cautioned that stable supply so far does not settle what happens if demand peaks during another fortnight of hot nights.
For Sirait, the discovery has changed the work he does. He now checks the surviving sensors each morning, before repairing chillers, and sends their readings to the research team. The cooperative had kept the loggers to predict cooling costs, not to measure climate change; some of its oldest sensors show that nights at several farms have warmed by nearly 2°C (3.6°F) since 2012.
The group says its forecast will be updated on 3 October as new readings arrive. Sirait has kept the recovered memory cards in a sealed plastic case beside his tools. “They were going to be thrown away,” he said. “Now people are using them to decide what to prepare for.”
