By AFP - Agence France Presse
Warming threatens to expand the area of the world too hot for humans
By Kelly MACNAMARA
Extreme heat will reach dangerous levels - even for younger people - in an area equivalent to the size of the United States if the Earth's global warming picks up by two degrees Celsius, scientists warned on Tuesday.
Climate change is causing an increasing number of deadly heatwaves around the world, exposing a growing number of people to conditions that test the limits of human endurance.
Last year, more than 1,300 people died during the Hajj pilgrimage in Saudi Arabia, where temperatures reached 51.8°C (125 degrees Fahrenheit).
For this study, published in the journal Nature Reviews Earth and Environment, the researchers analyzed global warming and the effects of scorching heat on the human body.
They found a significant increase in the area of the world potentially exposed to unsafe temperatures, with people in northern Africa and southern Asia most at risk.
They considered both dangerous and insurmountable levels of heat, where the body's core temperature rises to 42ºC in six hours.
The study concluded that between 1994 and 2023, heat and humidity reached unsafe levels for people under 60 in areas equivalent to around 2% of the global land area.
For the most vulnerable elderly, this figure rose to around 20% of the land area.
Lead author Tom Matthews said the research highlights the “potentially deadly consequences” of the Earth's average temperature rising by 2°C above pre-industrial levels.
The Paris Climate Agreement, a binding international treaty, aims to limit warming to “well below” 2ºC and preferably 1.5ºC.
Last year was the first to exceed 1.5°C on average.
With a warming of 2ºC, the researchers found that the amount of land mass that would become unsafe for younger adults would triple, reaching around 6%.
People over 60 would be at risk for around a third of the planet's land mass.
Insurmountable limits so far exceeded only briefly for people over 60 in the hottest regions of the planet, could also affect younger people in hot regions with very high levels of global warming.
“In these conditions, prolonged exposure to the outdoors, even for those in the shade, subject to a strong breeze and well hydrated, can cause lethal heatstroke,” said Matthews, senior lecturer in Environmental Geography at King's College London.
Heat stress occurs when the body's natural cooling systems are overloaded, causing symptoms ranging from dizziness and headaches to organ failure and death.
Even the lowest temperatures can be lethal when combined with humidity, as sweat cannot evaporate from the skin.
So far, Europe has recorded the highest number of deaths from heatwaves, with more than 70,000 deaths in 2003, 60,000 in 2022, and more than 47,000 in 2023.
Asia has also documented the high cost of rising temperatures, including several thousand deaths in India and Pakistan during heatwaves in 2015.
The researchers said that heat-related deaths in Africa were “chronically underreported”, but noted extreme heat in Nigeria in 2024.
The World Health Organization has calculated that heat kills at least half a million people every year but warns that the real figure could be up to 30 times higher.
klm/np/gil
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