Full Story Graham Readfearn steps into our climate future
Feb 17, 2026
Graham Readfearn, an environment and climate correspondent who tested extreme heat in a thermal chamber. He describes the treadmill trial at 43°C and how added humidity and solar load make heat much worse. He talks about sensors, rising heart rate and cognitive decline under unmanageable heat. He warns that near-term warming is already changing survival risks and city readiness.
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Self-Experiment In A Thermal Chamber
- Graham Readfearn entered a thermal chamber wired with sensors and walked on a treadmill to simulate future heatwaves.
- He described being weighed, fitted with skin sensors, a chest strap and a core thermometer placed internally for continuous monitoring.
Sunlight Amplifies Heat Stress
- At 43°C and 18% humidity a slow walk raised Graham's heart rate as his body pumped blood to the skin to cool down.
- The lab added solar lamps to simulate sun exposure, which notably increased thermal stress beyond shaded
Humidity Turns Sweat Into Liability
- Doubling humidity from 18% to 36% at 43°C raised the 'feels like' temperature to about 49°C and trapped sweat on the skin.
- High humidity prevented evaporative cooling, making core temperature keep rising despite heavy sweating.