Britain could become too hot to endure within the next three decades, warns new research.
The limit for human endurance may be as low as 104F (40C) which is set to become the norm by 2050.
An “upper critical temperature” has been identified at which resting metabolic rate increases – compromising the body’s ability to keep ticking over.
It lies between between 40 and 50° C (122.00 °F) – when people are exposed to warm and humid conditions.
Lead author Professor Lewis Halsey, of the University of Roehampton, southwest London, said: “Quite a lot of work has been done on the range of temperatures that different animal species prefer to live at in terms of their metabolic rates being minimal and thus their energy expenditure being low.”
“But, weirdly, information is much less available for humans when considering the upper limits of our thermal neutral zone.”
Professor Lewis Halsey as a participant in an experiment led by PhD student Chris Wolfe.
The hottest temperature in UK history of 104.54F (40.3°C) was recorded at Coningsby, Lincolnshire, 12 months ago.
Such heatwaves are set to become the norm in the coming years because of the burning of fossil fuels and other activities.
The study has implications for working conditions, sport, medicine and international travel
Halsey said: “This research provides fundamental knowledge about how we react to suboptimal environments, and how ‘optimal’ differs between people with different characteristics.”
His team is also investigating how heart function is affected by extreme temperatures – and how it varies due to age, physical fitness and other factors.
Halsey said: “We found some considerable changes in heart function responses to the heat between categories of people, the most novel being between the sexes.
“That is, on average, men and women display some key differences in their cardiovascular responses to the heat.”
Halsey and colleagues measured detailed heart function using a state-of-the-art ultrasound scan.
He said: “It was not easy to operate this kit in the heat. The sort of equipment you would see in hospitals but rarely in research laboratories.”
The ongoing investigations were presented at a meeting of the Society for Experimental Biology in Edinburgh.
Halsey said: “We are steadily building a picture about how the body responds to heat stress, how adaptable it can be, the limits to those adaptations, and – crucially – how varied responses are between individuals. In a warming world, this knowledge becomes ever more valuable.”
Last month was the hottest June on record in the UK.
Produced in association with SWNS Talker
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