When does heat become deadly? | ABC News

Fifteen years ago, scientists proposed an environmental threshold at which no person would be able to survive for six hours. But these conditions have never been tested on humans. Until now. A world-first study by researchers at the University of Sydney is challenging our understanding of how humans cope with extreme heat.
“This study is all about human survivability,” Dr Cheng says.
“So we are the first to actually put people in these environments to actually see, physiologically, what is happening to their core temperature or to their heart rate.
“What is happening to a real human when we put them in these environments?”
Tyne Logan reports.

00:00 - Intro
00:51 - Why heat is deadly
01:29 - The experiment
03:20 - What is wet bulb temperature?
03:40 - How humans cool down
04:08 - How humidity impacts your ability to sweat
04:55 - Examples of wet bulb temperatures in Australia
05:26 - Lab conditions
06:24 - Trying out the heat chamber
07:22 - Checking in on the participants
08:12 - Occurances of these temperatures in real life
09:07 - Global heat deaths
09:38 - Is the heat limit actually lower?
10:10 - Implications

References:
5 seconds:
Steven C Sherwood and Matthew Huber (2010), An adaptability limit to climate change due to heat stress. PNAS, Vol. 107 | No. 21

54 seconds:
Lucinda Coates et al. (2014). Exploring 167 years of vulnerability: An examination of extreme heat events in Australia 1844–2010. Environmental Science and Policy, Volume 42, 33-44

8 minutes 38 seconds:
Raymond et al.(2020). The emergence of heat and humidity too severe for human tolerance. Science Advances, Vol 6. Updated by Colin Raymond 2024

9 minutes 09 seconds
Elisa Gallow et al. (2024). Heat-related mortality in Europe during 2023 and the role of adaptation in protecting health. Nature Medicine

9 minutes 13 seconds:
Jennifer Vanos et al. (2023), A physiological approach for assessing human survivability and liveability to heat in a changing climate. Nature Communications

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