People in India and Pakistan suffer extreme weeks.

A temporary peak of the brutal heat wave was reached at the weekend: the weather station in Jacobabad, Pakistan, reported 51 degrees on Saturday, a new record was just missed.

These are unimaginable values ​​for Central Europeans, but the dry, scorching heat pushes even people who are used to the high temperatures in the densely populated region to their breaking point.

The heat wave is unprecedented because of its duration, since March one record has been chasing the next.

Climate researchers are concerned about what is to come – in the short term this early summer, but above all in the future.

Sixty degrees and more no longer seem unthinkable on planet earth, climate change could turn South Asia into a sauna from which there is no quick escape.

Andrew Frey

Freelance author in the science section of the Frankfurter Allgemeine Sunday newspaper.

  • Follow I follow

Even scarier is a scenario that has received significantly less research: extreme humidity.

Humid heat puts a greater strain on the organism than dry heat, and everyone feels that during steamy thunderstorms like this week: the higher the humidity in summer, the louder you can complain.

The only thing that helps is drinking and sweating.

However, if the outdoor sauna is transformed into a veritable steam sauna, even that no longer helps.

Hot and fully saturated air no longer absorbs water, sweat droplets on the skin's surface can no longer evaporate.

The natural cooling of the human being fails, and so humid heat becomes a killer: Without sweating, the body overheats, the core body temperature rises by more than one degree per hour.

Death occurs after a few hours.

This horror scenario does not come from a Hollywood script, but could become bitter reality in a climate that is heating up.

It occurs when the air is very hot and the humidity is very high at the same time - meteorologists speak of a very high wet-bulb temperature.

This measure of mugginess indicates the maximum temperature to which a moist surface, such as a person's sweaty skin, can be cooled by evaporation.

At 35 degrees, a critical value is reached, then a person is no longer physically able to dissipate heat to the environment because the temperature of the skin's surface corresponds exactly to the wet temperature.

Physiologists therefore speak of the maximum load limit of humans.

How much can a body endure?

The climate researcher Steven Sherwood from the University of New South Wales in Sydney published a comprehensive study on the subject twelve years ago in the journal "PNAS" and caused a great deal of scientific discussion.

At the time, he explained the thermodynamic view of this deadly phenomenon: "The limit of human endurance is the point at which you would overheat even if you were soaking wet and naked in the shade in front of a large fan."

A healthy person can endure something like this for half an hour, then it becomes life-threatening.

However, the extreme stress on the body does not begin at a hostile wet temperature of 35 degrees Celsius, but much earlier.

Even at values ​​of around 30 degrees, as they are currently being determined in India and Pakistan, it becomes dangerous for the elderly, infants and those with previous illnesses.

A current American study two months ago, even with young, healthy subjects, came to the conclusion that wet temperatures of 31 degrees are already critical.

According to the study, which was published in the "Journal of Applied Physiology", the core body temperature of the test subjects increased from this value.