France is experiencing an exceptional start to autumn. As a result of climate change, summer does not seem to be about to end. Still 28°C in Paris, 29°C in Bordeaux. This Sunday, October 8, temperatures are close to 30°C. And it’s not over: the heat will continue to dominate until Wednesday. It is only from Thursday that the weather should begin to slowly deteriorate, and autumn will then set in in earnest.
Last week, Monday October 2 marked the peak of the exceptional heat episode for this time of the year and even broke a record for maximums, Météo-France indicated on Tuesday. The mercury had then exceeded 35°C in the South-West, which is extremely rare in October. Enough to worry weather specialists who have their eyes glued to the thermometer. “Last night, at 1385m altitude in Puy de Dôme, in Chastreix, the temperature did not fall below 18.9° which is a record for nighttime mildness for the month of October!”, tweeted the weather presenter, Evelyne Dhéliat.
These exceptional temperatures come in the wake of a record September, the hottest ever recorded in many European countries, continuing a series of almost two years above seasonal norms in France. The hottest September on record follows August and the hottest July, the latter being the hottest month on record. Not to mention, high temperatures have caused heat waves and wildfires across the world.
The warning signs of a major upheaval.
These heat episodes are made more frequent and more intense by climate change of human origin, scientists estimate. They are also earlier and later. “Our climate is no longer static, it is constantly warming, and temperatures that were extremely unlikely in the past climate are becoming more and more so,” explains Météo France in its communicated dating from Friday October 6. Climate change does not create new atmospheric dynamics, but it amplifies its effects.
“The meteorological situation at the beginning of October is certainly very particular, with a powerful anticyclonic ridge covering the whole of France, supplied with heat by southerly winds, but the atmospheric machine has always been capable of producing this type of blockage” , resumes Météo France. In other words, masses of warm air coming from the Iberian Peninsula rise towards us and find themselves trapped under high pressures. And the hot air will be trapped. Nothing unusual so far except that the air will become hotter and hotter with global warming.
On Twitter, the anger of certain climate specialists is brewing, such as that of Christophe Cassou, research director at the CNRS: “When we have 50°C in Occitanie, I am impatiently awaiting the backpedaling of the supporters of the A69 – project Castres-Toulouse motorway criticized by environmentalists – who will swear to us that they did not know. And yet, each tonne of CO2 avoided limits warming & risks.” In a interview published in the newspaper South West, climatologist Jean Jouzel once again sounds the alarm: “We are experiencing the warning signs of a major upheaval.” For him, these autumnal heats are not surprising, since they have been described for around thirty years, “since the third IPCC report”.
A risk of drought
In Release, it is the turn of Christine Berne, climatologist at Météo France, to warn of the consequences of climate change. The specialist points out that the frequency of these late heat episodes in September and October is increasing: “Over the last six years, we have had this effect linked to climate change every year, except in 2021. In 2022, we had a first peak in September, then two episodes in October. Before, there had been September 2020, September 2019, September 2018…” And these heat episodes also risk increasing the drought. “Surface soil moisture is now starting to plummet due to lack of precipitation and high temperatures,” she warns.
And abroad too, climate specialists are expressing their concerns. In Australia, climatologist and author Joelle Gergis said: “Observations of Australia’s climate in September are shocking. The figures show where maximum temperatures were the highest on record, with many areas 3-5C above average. Rainfall deficits are conducive to drought.” As for Mika Rantanen, climatology researcher at the Finnish Meteorological Institute, there is still amazement: “I still have difficulty understanding how a single year can make such a big jump compared to previous years.”