Extreme heat creates 'non-survivable' conditions for humans, study finds

As summer approaches, blistering hot temperatures are set to be more than just a minor inconvenience.

What's happening?

According to a study published in March in the journal Nature Communications, extreme heat has already created what the co-authors called "non-survivable" conditions for human beings, leading researchers to find that people may be more susceptible to rising temperatures than previously thought.

In an effort to reexamine the impact of heat waves as they become increasingly severe, the researchers looked at humidity and body temperature regulation data from six extreme heat waves between 2003 and 2024, The Guardian reported.

While previous research had suggested that humans can survive for six hours at a wet-bulb temperature of 35 degrees Celsius (95 degrees Fahrenheit), six major heat waves had contributed to thousands of deaths despite never reaching that limit. Wet-bulb temperature accounts for both humidity and temperature.

With the new model of human survivability taking into account the body's ability to regulate temperatures and cool down, researchers could determine that all six heat waves were "non-survivable" for older individuals who could not get access to shade.

"My first thought was 'Oh s***' — I really didn't expect to see that, especially when you zoom in to individual cities," lead author Sarah Perkins-Kirkpatrick told The Guardian.

Why is extreme heat concerning?

As heat waves continue to last longer and become more severe in temperature, the zone of "non-survivable" conditions is expanding. There, older individuals without access to shade are among the more vulnerable groups but certainly not the only groups at increased risk.

Extreme heat has been linked to heat stroke, dehydration, and even death, making it especially dangerous to work or exert excessive amounts of energy outside during high temperatures.

Beyond the overt health impacts of extreme heat, the economic consequences can also be severe. 

Many communities and cities worldwide do not have the infrastructure or set protocols to handle oppressive heat waves. Damage to infrastructure, like buildings and sidewalks, can cost people and businesses a significant amount of money to repair. 

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Temporary preventative measures to beat the heat, such as fans and air conditioning units, can also threaten electric grids, influencing the likelihood of power outages during already precarious times.

What's being done about extreme heat?

As extreme heat becomes more prevalent, it is crucial for officials to implement regulations and infrastructure for systemic resilience. 

Fortunately, many cities utilize comprehensive heat response planning to prepare and protect citizens from forecasted heat waves. And development of passive cooling strategies — building designs that can cool interiors without mechanical systems — can improve access to safer and more comfortable living and working conditions.

On an individual level, it is important to seek shade, keep skin protected, and be wary of exerting energy in times of extreme heat and humidity. Hydration is especially critical for vital bodily functions and internal temperature regulation.

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