“Life-threatening” heat and humidity occurs worldwide due to global warming

The world now regularly becomes so hot and humid during heat waves that some places exceed the “theoretical limit of human survival”.

Scientists’ forecast of the Judgment Day predicted that it would happen due to global warming, but not for several decades.

But a study found that parts of the world have already become so hot and humid during heat waves that perspiration becomes unnecessary and the body is unable to cool itself.

If someone were left outside for several hours under these conditions, they would die.

The combination of extreme heat and high humidity creates what is known as a “wet bulb temperature”.

A wet bulb temperature of 35 ° C is considered life-threatening to humans and it was previously believed that it was impossible for anywhere on Earth to reach this dangerous level of heat and humidity.

However, the latest research reveals 14 occasions where this deadly combination has been reached in the United Arab Emirates, Saudi Arabia and Qatar since 1979.

“Previous studies predicted that it would happen in several decades, but it shows that it is happening right now,” said Dr. Colin Raymond, lead author of the California Institute of Technology.

“The duration of these events will increase and the areas they affect will increase in direct correlation with global warming.”

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In Bangladesh, one of the most vulnerable countries, a crew is digging a riverbed for a new bridge. Working outdoors is a way of life in many regions of the worst heat and humidity

In Bangladesh, one of the most vulnerable countries, a crew is digging a riverbed for a new bridge. Working outdoors is a way of life in many regions of the worst heat and humidity

A so-called “wet bulb temperature” of 35 ° C, which takes humidity into account, can be fatal after a few hours, even to the fittest person.

The wet bulb temperature of 35 ° C is rarely reached, but a reading of 32 ° C or 33 ° C can also be fatal if people exercise for long periods.

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Heat waves that have reached these dangerous conditions have more than doubled since 1979, according to new research.

The temperature of the wet bulb is sometimes used in weather forecasting as the temperature of the “heat index” or the “actual temperature”.

Under these conditions, perspiration becomes useless because the air is already saturated with humidity and therefore the perspiration beads do not evaporate.

This can then trigger a chain reaction which leads to constant internal warming, overheating and potentially heat stroke. In severe cases, this can be fatal.

Readings approaching or exceeding 30 ° C on the wet bulb have doubled since 1979.

The study showed that the number of readings at 31 ° C, long considered a rare event, occurred more than 1,000 times.

The sweltering heat felt at a wet bulb temperature of 33 ° C was identified 80 times. It was previously considered almost non-existent.

According to Columbia University researchers, more than a dozen recent measurements in the Persian Gulf have exceeded the theoretical limit for human survival by 35 ° C. At the scale of actual sensation, this equates to approximately 160 °. F, or 71 ° C, depending on the study.

“It is difficult to exaggerate the effects of everything that enters the 1930s [on the wet bulb temperature scale]”Said Dr. Colin Raymond, of the California Institute of Technology, Pasadena, who participated in the research.

"Life-threatening" heat and humidity occurs worldwide due to global warming

"Life-threatening" heat and humidity occurs worldwide due to global warming

New study shows that extreme, sometimes life-threatening mixtures of heat and humidity are emerging around the world. This map shows documented examples, with warmer colors from yellow to red signifying the worst combinations measured on the “ wet bulb ” scale.

WHAT IS THE WET BULB TEMPERATURE?

The “wet bulb temperature” (TW) is measured by attaching a damp cloth to the bulb of a thermometer.

It is a direct indicator of how sweating cools the body.

It changes depending on the actual temperature and humidity, but if the TW peaks above 103 ° F, the body can no longer cool down.

These are then defined as “ dangerous ” by the National Weather Service of the United States and if they reach 124 ° F or more, they present an extreme danger.

The heat and humidity causing a “wet bulb temperature” of this enormity can lead to an intake of heat which can in turn cause damage to the brain, heart, kidneys and muscles.

At an actual temperature of only 90 ° F, if the humidity rises to 95%, it can reach the threshold of 124 ° TW for “extreme danger”.

However, if the humidity remains low, say around 45 percent, the actual temperature should increase to a roast of 104 ° F before the “extreme danger” limit is reached.

A so-called “wet bulb temperature”, which takes humidity into account, of only 35 ° C can be fatal after a few hours, even to the fittest person.

The wet bulb temperature of 35 ° is rarely reached, 32 ° or 33 ° can also be fatal if people exercise for long periods.

The temperature of the wet bulb is sometimes used in weather forecasting as the temperature of the “heat index” or the “actual temperature”.

So far, the epidemics have been limited to localized areas and have lasted only a few hours. However, they are now increasing in frequency and intensity, warn the authors.

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Dr. Tom Matthews of Loughborough University said: “ A wet bulb temperature (TW) of 35 ° C marks our upper physiological limit, and much lower values ​​have serious implications for health and productivity.

“Climate models project the first occurrences of 35 ° C TW by the middle of the 21st century.

“However, a full evaluation of the data from weather stations shows that some coastal subtropical sites have already reported a TW of 35 ° C and that the extreme humid heat overall has more than doubled in frequency since 1979.”

Dr. Raymond adds: “Heat and humidity beyond what the human body can tolerate emerge before the projections.”

The analysis is the first to show that the temperature of the wet bulb in some places has already exceeded 35 ° C, at which people can no longer regulate their own body heat.

The study collected hourly data from 7,877 weather stations between 1979 and 2017 and looked for periods of extreme weather conditions.

Dr. Matthews also found that dangerous episodes above 27 ° C have more than doubled since 1979.

These extreme temperatures had not been identified before because the events were brief and very localized.

The complete results were published in the journal Science Advances.

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