When temperatures approach 50°C, as was recently the case in India and Pakistan, but also in Australia, Canada and the United States, they can become deadly. By becoming more frequent and more intense, extreme heat waves and heatwaves endanger both agricultural production and human health…
The meteorologists warned us in the IPCC reports successive: global warming risks causing waves and heat domes more and more frequent in the future. Yes, yes, even in France…
Can you really die from heat?
You can die from heat when the body is no longer able to maintain its internal temperature. To maintain the right temperature, close to 37° C, the body has two regulatory mechanisms : first, the simple air contact and, then, the sweating which absorbs a lot of energy and refreshes us.
In a dry environment, we can withstand high temperatures, above 45°C, but in a very humid environment, we are much less well equipped to resist. The tolerable limit in an environment with a humidity level of 100% is rated at 35°C.
The reason is simple to understand: as the air is saturated with water due to ambient humidity, the body sweating can no longer evaporate to cool it. Body temperature then tends to increaseone degree every 45 minutes and we see irreversible damage around 42°C.
The organism then goes through states of dehydrationexhaustion, heat cramps, and even delirium. You end up having trouble breathing, then you lose consciousness. Even in the event of relief, the death rate then becomes significant.
What to do to protect yourself from extreme heat?
In our Western societies, people most at risk Faced with extreme heat waves are first and foremost the homeless, but also people who work on the street, such as delivery men or drivers of small means of transport.
If there is a threat of extreme heat, we must react well before approaching this limit of 35° C. So what should we do?
- First, hydrate well by drinking at least one 1.5 liter bottle of water per day. The major risk in extreme heat remains dehydration.
- Seek coolness when possible and, at the very least, seek shade.
- Avoid physical exertion as much as possible so as not to unnecessarily increase body temperature.
Today, these phenomena still remain rare on a global scale. They are mainly concentrated in South Asia (India) and the Middle East. But, as the climate warms, these extreme heat waves are likely to become more frequent. The probabilities of reaching the 35°C threshold will necessarily increase.
France is not immune
Today, the risk is not yet that a territory becomes sufficiently inhospitable to become uninhabitable. On the other hand, we could occasionally experience waves of mortality important when these phenomena occur.
As seen in North America in 2021 or in Australia in January 2022, no one is safe from this type of event. Who had anticipated a temperature of 50°C in Western Canada?
France itself is not spared: even without reaching unbearable temperatures for the human body, exceptional heat waves can have dramatic consequences. The heatwave episodes during the summer of 2003 proved this to us by causing at least 15,000 deaths in France.
The first reflex to adopt in the event of an alert is to remain attentive to heat stroke symptoms : red, hot and dry skin (without sweating), intense headaches, nausea or vomiting, discomfort, confused speech, etc. It is then imperative to contact the SAMU (15 or 112).
These rarely observed phenomena demonstrate that global warming risks having a growing impact on mortality.
