France explodes the thresholds of heat waves

• France is affected by its third heat wave since the beginning of the summer.

  It started on July 31 and should last at least the whole week.

• “At the national level, since July 17, France has set a new record for soil drought every day (on a history that begins in August 1958)”, notes Météo-France.

  A situation that could worsen in August when temperatures remain very high.

• 20 Minutes

  looks at these successive heat waves, thanks to the analysis of Christine Berne, climatologist at Météo-France.

It's hot, hot, hot this week in France.

The heat wave affecting France has not ended and should culminate with a scorching peak on Friday in most of the country.

Alerts are multiplying but are they still adapted to global warming?

takes stock.

Do episodes of high heat get worse?

This summer, France has already suffered three heat waves.

A first in June, lasting five days, another in July, long fourteen days, and the one we are currently going through and which began on July 31.

“The heat waves are becoming longer and more intense, but unfortunately this is not a surprise,” says Christine Berne, climatologist at Météo-France.

“This summer and this week, there will still be heat wave vigilance,” she predicts, estimating that at least twenty departments will be affected.

The summer has already been particularly hot.

And “a new heat wave could occur in September.

We are on a trend with summers that have and will have a lot of heat wave days.

»

According to the climate simulations of the Drias report, if we continue the current curve of our greenhouse gas emissions – which increase each year, at the end of the century we will experience between 20 to 50 more days of heat waves.

The trend is clear: between 1947 and 2019, weather experts count 45 heat waves (not counting the one we are experiencing these days).

Of these 45 waves, only nine took place before 1989.

Are our alert thresholds still appropriate?

After the 2003 heat wave, climate experts defined thresholds.

The heat wave is “the first threshold, the first alert” calculated on a national scale.

The country enters a heat wave "when we have for several days the threshold of 25 degrees which is exceeded, by averaging all the temperatures night and day", explains the climate expert.

Heat waves are calculated on a departmental scale and are therefore more precise.

"We haven't changed them for twenty years and with global warming, temperatures are rising, so these thresholds for heat waves and heat waves are more frequently exceeded," admits Christine Berne.

In summer, heat waves and heat waves seem to follow one another.

Between 1976 and 2005, "heat waves were relatively rare in most of the territory with less than five days a year", underlines the Drias report.

The 2022 summer season has already exploded the counters.

“In the fall or winter, we will have more perspective on the summer to ask ourselves the question of the definition and see if it is even more relevant or if the thresholds should be increased”, explains the meteorologist.

However, the notion is “not artificial”, she believes.

For heat waves, it protects residents because the thresholds set up in collaboration with Santé Publique France encourage vigilance.

As for heat waves, they are "a very significant impact on human activities" and their frequency this summer "implies that it is not raining and that there is drought".

A crucial situation for our agriculture or even our access to drinking water.

How can these indicators help us cope?

Experts develop thresholds and projections to inform the government and to protect populations.

The thresholds of heat waves are also managed by the Ministry of Health.

Orange or red alerts are activated more quickly in regions that are not usually subject to this torrid climate.

"The organisms get used to it and the habitat is more adapted to the heat in certain regions", emphasizes Christine Berne.

In the South, the French are accustomed to strong summer heat.

They have therefore integrated good protection habits.

“But in 2003, we realized that people further north didn't have the reflex to close the shutters in the morning and didn't protect themselves at all from the heat during the day,” recalls the climatologist.

The exceptionally hot summer of 2003 caused the death of around 15,000 people.

Our dossier on the heat wave

Sounding the alarm can allow health organizations to turn to the most vulnerable, authorities to communicate the right actions and residents to realize the extent of the phenomenon.

In the event of a heat wave, it is obviously necessary to turn on the air conditioning in nursing homes, for example.

But in the long term, “we will have to modify the dwellings, better insulate them”, adds Christine Berne.

Because we have not finished being hot.

Company

Heat wave: The heat wave will continue in France, with a peak at the end of the week

Planet

Hot weather: Météo-France predicts a further rise in temperatures

• Planet

• Heat

• Heat wave

• Temperature

• Meteo France

• Global warming