Even if we meet the Paris Agreement’s target, the planet will still be 2°C hotter than preindustrial times by the century’s end. Fewer regions will remain livable. Global temperatures have already climbed by 1.5°C. Scientists warn that another 0.5°C could make vast areas uninhabitable. Land the size of the U.S. could become too hot for humans due to the changing climate.
For those over 60, the danger is greater. Nearly 35% of Earth’s land could be too hot for older adults, rising from 21% today.
CLIMATE CRISIS; ESCALATING THREAT OF DEADLY HEAT
Climate expert Tom Matthews from King’s College London warns that even at 2°C warming, extreme heat will be a threat. It will endanger survival in many regions.
“At 4°C warming, nearly 40% of global land will experience uncompensable heat,” Matthews explains. Only high-latitude and some mid-latitude areas will stay habitable due to climate conditions.
Human Limits to Heat Tolerance
Humans tolerate heat only to a point. Sweating and fatigue signal early strain. Yet, beyond a certain threshold, the body fails to regulate temperature.
‘Uncompensable heat’ occurs when heat intake surpasses the body’s ability to cool itself. Firefighters and athletes frequently face this, but it’s becoming common during extreme heat waves, exacerbated by climate change.
REGIONS ALREADY EXPERIENCING EXTREME HEAT
Several areas already experience temperatures beyond human tolerance. The Persian Gulf, Indo-Gangetic Plain, southern US, Mexico, and Australia report extreme heat events that surpass human limits.
Unsurvivable heat occurs when body temperature, typically 37°C, reaches 42°C in six hours. At 2°C warming, this risk will mainly impact adults over 60.
CLIMATE CRISIS; WHAT HAPPENS IF WE EXCEED 2°C?
If fossil fuel emissions continue unchecked, we may surpass the 2°C target. At 4-5°C warming, the consequences could be catastrophic.
Older adults may experience uncompensable heat across 60% of Earth’s surface. Meanwhile, unsurvivable heat will become a serious threat in the tropics, home to 40% of the global population, particularly concerning from a climate perspective.
A LOOMING PUBLIC HEALTH EMERGENCY
Matthews warns that extreme heat will increasingly impact even younger adults. “Unsurvivable heat thresholds, once rare, will become common,” he states. “Even with shade, a breeze, and hydration, heatstroke could be fatal.”
This shift in heat-related mortality risk calls for immediate climate action.
PREPARING FOR A HOTTER FUTURE
To prevent the worst outcomes, limiting global warming is crucial. This requires switching to renewable energy and preserving carbon-absorbing ecosystems.
Preparation is also key. Many regions must adapt to a reality where being outdoors becomes hazardous to health due to the climate.
“As more areas face deadly heat, access to cooler environments will be vital,” says Matthews.
The future depends on decisive climate action. A world 2°C warmer presents challenges, but at 4°C, catastrophe looms. Without urgent intervention, entire regions may become uninhabitable.
