Extreme heat may render planet too hot for human survival – Report

Says 260,000 people died from condition in 5 years   A study published in the journal, Nature Reviews Earth and Environment has indicated that rising global temperatures may render extensive regions of the planet too hot for human survival over the coming decades. The new study led by King’s College London, shows that if worldwide warming […]

• Says 260,000 people died from condition in 5 years

 

A study published in the journal, Nature Reviews Earth and Environment has indicated that rising global temperatures may render extensive regions of the planet too hot for human survival over the coming decades.

The new study led by King’s College London, shows that if worldwide warming surpasses 2°C above pre-industrial levels, the proportion of land experiencing unsurvivable heat will triple, spanning an area nearly as large as the United States.

“These extremely high temperatures would endanger healthy young adults (aged 18–60), pushing their bodies past the point where they can regulate internal heat – even with adequate shade and hydration. Moreover, older adults (60+) would be at high risk across nearly 35% of the global land surface.”

The study lead, Tom Matthews, a senior lecturer in Environmental Geography at King’s College, London said: “Our findings show the potentially deadly consequences if global warming reaches 2°C. Unsurvivable heat thresholds, which so far have only been exceeded briefly for older adults in the hottest regions on earth, are likely to emerge even for younger adults.”

“In such conditions, prolonged outdoor exposure, even for those in the shade, subject to a strong breeze, and well hydrated, would be expected to cause lethal heatstroke. It represents a step-change in heat-mortality risk.”

With 2023 recorded as the first full year averaging more than 1.5°C above pre-industrial norms, many scientists caution that 2°C could be reached by the middle to latter half of this century if present trends remain unchecked.

The researchers connect physical climate science to human heat-mortality risks by focusing on uncompensable heat, a critical point where the human body cannot effectively release heat, resulting in a perilous increase in core temperature and unsurvivable heat, the point at which core body temperature rises to 42°C within six hours, invariably resulting in fatal outcomes.

It said between 1994 and 2023, about 2% of earth’s land area exceeded the uncompensable threshold for healthy adults under 60. By contrast, over 20% of global land already reached those levels for older adults during periods of intense heat.

According to the experts, since 2000, more than 260,000 people have died from extreme heat during major heatwaves, a finding highlighting the scale of heat-related dangers.

Although 2°C of warming carries serious risks, the study also indicates that a 4–5°C rise could be catastrophic.

“Moreover, at 4°C above pre-industrial levels, around 40% of the globe would regularly endure uncompensable heat, restricting tolerable conditions largely to high-latitude and cooler mid-latitude areas.”

He said such projections place regions like Saharan Africa, South Asia, and parts of the Middle East in particular jeopardy, where even limited outdoor exposure might become life-threatening.

“At around 4°C of warming above pre-industrial levels, uncompensable heat for adults would affect about 40% of the global land area, with only the high latitudes and the cooler regions of the mid-latitudes remaining unaffected,” Matthews explained.

While suggesting rapid cuts in greenhouse gas emissions, the study emphasised the need to protect vulnerable groups through measures such as revamping urban design to mitigate heat via increased greenery and reflective surfaces, boosting cooling infrastructure, from widespread air conditioning to designated cooling centers and ensuring sufficient water and resource availability in heat-prone regions.