At forty degrees Celsius (in the shade) you can wonder how lucky it is that there are only a limited number of days with such scorching temperatures during the year. But when climatologists ask if in the future we global warming awaits more or less similar hellish days, they answer that we are actually faced with a grim choice between more or many more such days with extreme temperatures.
Ever since a NASA study in 1958, a comfort zone of temperature between 4 and 35 degrees Celsius has been established, where, when the humidity does not exceed 50 percent, people can stay indefinitely. But when it is outside this zone, how high a temperature can the human body withstand?
Despite numerous, mostly military researches, there is no general and precise answer to this question. Different people can withstand different temperature extremes, and it depends on the way of clothing, physical activities, air flow and shelter from the sun. And above all, from air humidity.
The reaction of the human body to the same temperature at different air humidity is completely different. In order to maintain the body temperature at around 37 degrees, the organism at high air temperatures releases excess heat primarily through evaporation, i.e. sweating. However, if the relative humidity around it is high, evaporation is slower and the person perceives that the outside temperature is higher than the one measured by thermometers.
At a very high relative humidity, a person can be at risk as early as 36 degrees Celsius, while in deserts, where the air is extremely dry, people can survive ten minutes at a temperature of 60 degrees.
Therefore, in such discussions about temperature and humidity, the term "humidity thermometer" is often used, which is the instrument that meteorologists normally use. Unlike the so-called dry one, which is an ordinary thermometer, the wet one is wrapped in a muslin or linen cloth soaked in distilled water. Evaporation consumes heat, so this thermometer shows a lower temperature, and the difference between wet and dry temperature is proportional to air humidity.
It is generally accepted that at a dry bulb temperature higher than 54 degrees Celsius, the human body will inevitably suffer from heat stroke. This form of hyperthermia can also occur at much lower temperatures, and it can be influenced by drugs, alcohol, age, and other circumstances. Athletes competing in the heat can be at risk, and statistics show that children left behind in uncooled cars are frequent victims of heatstroke.
Heatstroke is an extreme state of thermal stress and leads to an increase in body temperature in just a few minutes, dizziness, bleeding, collapse of the cardiovascular system, convulsions, coma, muscle and organ failure and, in the most severe case, to death.
Planet Earth is undoubtedly warming due to man's merciless burning of fossil fuels and the emission of carbon dioxide, but climate change does not mean that the temperature will rise equally everywhere.
Namely, the models show that with an increase in the average global temperature by 1,5 degrees by the end of the century (which is the limit that implies that we have managed to stop the emission of CO2 by half of the century), the number and intensity of various types of extremes will actually increase - from precipitation to heat wave. Both ice and heat waves will be more dramatic and devastating. In some regions, where heat waves last a total of 20 days a year, even half a year of extreme temperatures is predicted.
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