by Ruggiero Corcella
While Italy and other European countries are struggling with the problems caused by excessive temperatures, the effects on the Indian subcontinent appear to be more moderate.
People continue to die from heat, but are they dying less? And if so, for what reason? Are the reports wrong or are we facing a new trend in humanity, more resilient to extreme phenomena caused by climate change? These are some of the questions David Wallace-Wells attempts to answer in an article published in The New York Times.
war report
Here and in Europe, the heat emergency is now a war bulletin: African high pressure is coming for at least 10 days, which will bring further heat and drought to the bitter end. France and Spain are burning and the fires are countless. A yellow alert has been issued in the UK for forecasting record temperatures of up to 40 degrees Celsius. An exceptional situation involving a meeting of the Cobra (Cabinet Office Briefing Rooms), the UK Government’s coordination and strategy committee set up to respond to a national or regional crisis. On the other side of the world, however, the monsoon season has arrived. A moment that allows us to take stock of the consequences of the heat waves that have hit South Asia in exceptional succession since this spring.
The situation in India
From late March to late June, a nearly 100-day period, the grueling heat spread across much of the Indian subcontinent, often blanketing more than a billion people and reaching over 50 degrees (Celsius) in some places. In May, the World Weather Attribution Initiative, a research alliance that links extreme events to global warming in real time, said climate change had made the first wave 30 times more likely. According to the scientists, the maximum survival limit for humans is when the combination of heat and moisture produces a so-called wet-bulb temperature of 35 degrees Celsius for six hours. Above this level, it is believed that exposure would also kill young and healthy people.
However, according to the NYT report, an initial estimate of the death toll is as low as 90 in India and Pakistan, a fraction of the more than a thousand people killed by the heatwave that hit the Pacific Northwest (including western Canada) last summer. where the lowest temperatures hit millions for a much shorter period of time. an even smaller fraction of the number of deaths in the 2003 and 2010 heat waves in Europe and Russia, which killed 70,000 and 55,000 people respectively. During these heat waves, only a handful of locations surpassed 40 degrees.
How our body reacts to heat
Why did so few people die (but definitive data are still lacking) given such high temperatures, lasting well beyond the canonical six days that science has suggested as the maximum tolerable limit for humans? What’s happening? To understand this, we must first make a premise and explain human physiology. Basically, the topic is as follows: The high temperature with high humidity is dangerous. With a relatively low level of humidity and a minimum of ventilation in the environment where the heat wave occurs, the health risk is much lower, since human thermoregulation allows it to survive even a certain number of consecutive days of high temperatures unscathed. explains Professor Alessandro Miani, President of the Italian Society for Environmental Medicine (Sima).
Because sweating is our first form of internal temperature regulation. So when the relative humidity is low and we manage to perspire, our sweat has time to evaporate and thus draw heat away from the human body, allowing all important vital functions to be kept active. In windy conditions, this facilitates the evaporation of sweat. On the other hand, when the relative humidity is very high, this mechanism tends not to work or works much more slowly, leading to very serious situations that can lead to death. This is independent of any area of the world, adds the expert.
The five hypotheses
So much for the mechanisms that regulate human response to extreme heat. But what are the explanations for the phenomenon that, if confirmed by epidemiological data, could shed new light on the relationship between humans and climate change? At the NYT, five are accepted: issues with dates; dry heat wave; the role of cultural practices and adaptation; the hottest parts of the world may already be relatively acclimatized to extreme heat; Our occasional use of wet-bulb temperature measurements can be misleading as to actual mortality risk.
The data problem
Let’s start with the first hypothesis: in reality, the deaths recorded in India and Pakistan are underestimated. We are certainly seeing that now, for example with Covid. The security of the data depends on the level of preparation and the capacity of collection also of epidemiology centers able to detect a death for a specific cause or possibly reported for causes other than death – explains Miani -. Thus, the deaths attributable to these phenomena often pass not as deaths from heat but as deaths from other pathologies, which is why they are not marked with a specific classification. a predominantly cultural issue of preparation and also the capillarity of healthcare in a country and cultural preparation to understand that a collapse, a heart attack, rather than another, say, cause of death, is due to high temperatures or perhaps a level of dehydration even small.
Extremely hot but dry
The second hypothesis instead refers to the greater presence of a hot, dry climate. So: Dry heat makes life possible, humid heat makes it extremely difficult because the human body cannot have sufficient thermoregulation, emphasizes the President of Sima. Third likely answer, cultural practices and adaptation. Absolutely yes. Populations that have a life practice or are used to living in less comfortable conditions than we Europeans certainly have an innate adaptability. Could the world’s hottest countries be relatively less prone to heat? I have some doubts about that, because the hottest countries in the world have to suffer less. Certainly a country where populations that have been accustomed to higher temperatures for centuries have not acquired such an adaptation – for human adaptation to change is not a matter of hundreds of years but of thousands or tens of thousands of years and unfortunately today the environment is running very much faster than our adaptability – but more of a cultural issue.
Are we more resilient?
The last hypothesis states that the wet-bulb temperature parameter for defining the limits of human thermal resistance is not as accurate. To date, I have not read any article that would be of significant importance in terms of determining this parameter – replies Miani -. So it probably should be better studied and perhaps better studied in countries where the science is good for you. The point always remains, in my opinion: a question of humidity and ventilation. We can also spend a month or two months or three months at 33 if the weather is dry and there is some ventilation. We think of the nomadic peoples who live in the desert. My opinion that this could be a topic that we could maybe do some research on as well.
The future
How should we behave in the face of the dangers of climate change? Climate change was not born yesterday, we have been seeing its effects for seventy years, it affects everyone and affects everything and we must – very quickly, without discussing possibilities or not and special interests or not – focus on the fossil ones as much as possible Sources refrain because it is the main cause of climate change and rising temperatures, Miani concludes.
July 15, 2022 (change July 15, 2022 | 13:43)
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