Global warming now pushing heat into territory humans cannot tolerate
The explosive growth and success of human society over the past 10,000 years has been underpinned by a distinct range of climate conditions.
But the range of weather humans can encounter on Earth – the “climate envelope” – is shifting as the planet warms, and conditions entirely new to civilisation could emerge in the coming decades. Even with modern technology, this should not be taken lightly.
Being able to regulate our temperature has played a key role in enabling humans to dominate the planet. Walking on two legs, without fur, and with a sweat-based cooling system, we’re well designed to beat the heat.
But hot weather already limits our ability to work and stay healthy. In fact, our physiology places bounds on the level of heat and humidity we can cope with.
The normal temperature you see reported on weather forecasts is called the “drybulb” temperature. Once that rises above about 35°C, the body must rely on evaporating water (mainly through sweating) to dissipate heat.
The “wetbulb” temperature is a measure that includes the chilling effect from evaporation on a thermometer, so it is normally much lower than the drybulb temperature. It indicates how efficiently our sweat-based cooling system can work.
Once the wetbulb temperature crosses about 35°C, the air is so hot and humid that not even sweating can lower your body temperature to a safe level. With continued exposure above this threshold, death by overheating can follow.
A 35°C limit may sound modest, but it isn’t. When the UK sweltered with a record drybulb temperature of 38.7°C in July 2019, the wetbulb temperature in Cambridge was no more than 24°C.
Even in Karachi’s killer heatwave of 2015, the wetbulb temperature stayed below 30°C. In fact, outside a steam room, few people have encountered anything close to 35°C. It has mostly been beyond Earth’s climate envelope as human society has developed.
But our recent research shows that the 35°C limit is drawing closer, leaving an ever-shrinking safety margin for the hottest and most humid places on Earth...
Dr Tom Matthews, of the School of Social Sciences and Humanities, and Colin Raymond, a Postdoctoral Researcher at the California Institute of Technology, discuss their latest study in the Conversation.
Read the full article here.
Their research paper, titled 'The emergence of heat and humidity too severe for human tolerance', can also be found here.
Notes for editors
Press release reference number: 20/80
Loughborough University is equipped with a live in-house broadcast unit via the Globelynx network. To arrange an interview with one of our experts please contact the press office on 01509 223491. Bookings can be made online via www.globelynx.com
Loughborough is one of the country’s leading universities, with an international reputation for research that matters, excellence in teaching, strong links with industry, and unrivalled achievement in sport and its underpinning academic disciplines.
It has been awarded five stars in the independent QS Stars university rating scheme, named the best university in the world for sports-related subjects in the 2019 QS World University Rankings, University of the Year by The Times and Sunday Times University Guide 2019 and top in the country for its student experience in the 2018 THE Student Experience Survey.
Loughborough is in the top 10 of every national league table, being ranked 4th in the Guardian University League Table 2020, 5th in the Times and Sunday Times Good University Guide 2019 and 8th in The UK Complete University Guide 2020.
Loughborough is consistently ranked in the top twenty of UK universities in the Times Higher Education’s ‘table of tables’ and is in the top 10 in England for research intensity. In recognition of its contribution to the sector, Loughborough has been awarded seven Queen's Anniversary Prizes.
The Loughborough University London campus is based on the Queen Elizabeth Olympic Park and offers postgraduate and executive-level education, as well as research and enterprise opportunities. It is home to influential thought leaders, pioneering researchers and creative innovators who provide students with the highest quality of teaching and the very latest in modern thinking.