Tropical and subtropical areas, including Brazil, may have temperatures considered “dangerous” to human health for most of the year, as the climate crisis progresses through the 21st century. Places on the planet with billions of people, such as India and Sub-Saharan Africa, may experience more days with “extremely dangerous” temperatures.
This is what a research published this Thursday (25) in the scientific journal Communications Earth & Environment shows.
The planet has already warmed, in relation to the pre-industrial period (taken as the time span between 1850-1900), by just over 1°C. The authors of the research say that, if no drastic changes are implemented, by 2050 we will reach a 2°C increase, the warming limit set as a target in the Paris Agreement – according to which, preferably, we should stay at up to 1, 5°C, which currently seems like a lost target.
In the research, the scientists used a heat index, which takes into account, in addition to temperature, humidity. Such data is summarized in a temperature. Basically, you can take the index as the wind chill. This is important because one of the ways the human body regulates temperature is through sweat. However, when the humidity is higher, the evaporation of sweat is more difficult and the body ends up warmer.
According to the US climate service, a heat index of 39°C is already considered “dangerous”. In this situation, it is already possible to experience cramps and exhaustion, and, in cases of prolonged exposure or physical activity, there is a risk of strokes associated with temperature.
51°C, again following the index, marks the entry into the “extremely dangerous” zone. In this situation, heat strokes are likely, according to the US climate service, and can lead to death.
Scientists have applied this index to different parts of the globe to understand the impact of the climate crisis on regional heat stress.
Based on historical data from 1979 to 1998, the scientists observed that situations where the index entered the hazard level occurred on only about 5% of days annually in tropical and subtropical areas. In the subtropical African area, the Indian subcontinent and the Arabian peninsula, the same occurred on about 10% to 15% of days each year.
In mid-latitudes regions, such as Europe and part of the USA, the index classified as dangerous was still rarely reached. In some of these regions, this was an extreme event, with an occurrence restricted to less than once a year.
But thanks to the climate crisis caused by human action, the situation is expected to heat up around the world. In tropical and subtropical areas, until 2050, days with dangerous heat index should occupy, for certain populations, from a quarter to half of the year. By the end of the century, most of these regions will be able to live with dangerous rates on most days of each year, the researchers estimate.
On the other hand, mid-latitude regions may have 15 to 90 days a year with heat indices considered dangerous.
By the end of the century, the rare days with extremely dangerous rates could become regular, occurring on more than 15 days a year, in sub-Saharan Africa, in parts of the Arabian Peninsula and in much of the Indian subcontinent.
In high emission scenarios (when talking about climate projections, scientists always estimate several possible scenarios for human emissions of greenhouse gases), some tropical and subtropical regions may experience 15% to 25% of the days of the year with extremely dangerous rates. for human health.
The concern with extreme heat situations is related to the risk of deaths and the need for society to adapt to the future climate we will face.
“The health consequences of regular high temperatures, particularly for the elderly, the poor and people working in the sun, outdoors, can be profound and necessitate basic reorientation of risk, even at mid-latitudes,” they conclude. the scientists.
_183224.jpg?fit=%2C&ssl=1)
