Violent Mediterranean episodes multiplying as the temperature rises

These are deluges so sudden and brutal that they can direct to scenes of devastation and tragic results. 6 individuals died in the southern French departments of Gard and Ardèche around the weekend adhering to violent storms that swelled rivers and triggered serious flooding. Since early February, France has been strike by 3 of these phenomena recognised as “Mediterranean episodes,” which are scarce in winter.

“All the components ended up there as the French Mediterranean locations have been strike by a succession of disturbances,” explained Aurélien Ribes, a researcher at Météo-France’s (France’s nationwide temperature company) Nationwide Center for Meteorological Analysis (CNRM).

On March 9 and 10, storm Monica introduced heat, dampness-laden air from the Mediterranean Sea to the south of France. When it hit mountains and the air rose and cooled, top to hefty precipitation. The storm units were being all the extra powerful as they stagnated in the same regions, trapped by the mountains. Cumulative rainfall, for illustration, arrived at 110 to 160 millimeters in 24 hours on Mont Aigoual and the Causses, 100 to 140 millimeters in the Nîmes hinterland, and between 170 and 180 millimeters towards Villefort.

An amplifying ingredient

“The soils, now saturated with drinking water subsequent the winter’s numerous disturbances, produced runoff that turned into floods,” extra Cindy Lebeaupin Brossier, a researcher at CNRM, who took section in the HyMeX research program conducted involving 2010 and 2020 to improved understand Mediterranean temperature situations.

These heavy rainfalls, which come about on average a few to 6 periods a yr in France – with sizeable variability – most typically come about in the drop, when there is a sharp distinction among Mediterranean temperatures and individuals at increased altitudes. In truth, having said that, they can take place at any time of year. “It truly is rarer, but not unheard of, to observe these kinds of functions in March,” stated Lebeaupin Brossier. Precedents have occurred in the exact same month in 2022, 2018, 2013 and 2011, in the Hérault, the Cévennes and the southern Pyrénées-Orientales places.

Have large temperatures in the Mediterranean and, previously mentioned all, the Atlantic Ocean, or the very warm winter recorded in France performed a role in the event of these types of phenomena in current weeks? “Mediterranean warming is not a set off, but an amplifier,” defined Lebeaupin Brossier. There is no indicator of any transform in the seasonality of these flash floods.

Urbanization, a possibility component

The amount of Mediterranean climate situations is not growing as a end result of local climate adjust. But the strongest functions are getting to be far more powerful and a lot more regular. “Between 1961 and 2022, we noticed a doubling in the frequency of the strongest Mediterranean weather functions, those exceeding 200 millimeters of rain in a one working day, and an raise in heavy precipitation,” reported Aurélien Ribes.

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