climate The summer of 2022, a marker of global warming? “We are witnessing a Mediterraneanization of Brittany”


Drought, fires, violent storms… In Brittany, the summer of 2022 was marked by exceptional weather phenomena. Warning signs of inexorable climate change? Response items with Anne-Marie Treguier and Vincent Dubreuil, co-chairs of the Breton High Council for Climate. More and more hot, even very hot, days in summer, fewer and fewer frosty days in winter, milder springs, warmer autumns are parameters that allow us to observe climate change in Brittany. A slow progression marked by extreme episodes such as the drought of the summer of 2022. “In a warming climate, explains Anne-Marie Treguier, co-president of the Breton High Council for the climate, extremes, rare in the past, it will be more and more frequent”. This oceanographer, also director of research at the CNRS in Brest and co-author of the 6th report of the IPCC (Intergovernmental Panel on Climate Change), reminds us that the observation of changes is not done by comparing a year with the previous one, “but rather from a multi-decade perspective”. An important precision if we are to take the true measure of what is happening on a planetary scale. Who was to say that Britain would ever suffer a rain deficit ?However, it is a reality. Groundwater levels are at a low level according to a bulletin published by the Bureau of Geological and Mining Research (BRGM) at the end of August 2022. This decrease in the resource is explains in part by a winter with very little rain bear 2021-2022. Take, for example, the animated map below which compares the emergency levels of the drought decrees still in place in Brittany at the end of September 2021 and 2022. It shows that the restrictive measures taken by the Breton departments have nothing to do with those . from last year Thus, as of September 20, 2022, the entire region of Brittany remains on “drought crisis” alert, while in 2021 only two departments, Morbihan and Ille-et-Vilaine, were still on alert and at the lowest of the thresholds, that of “surveillance”. It should also be noted that the restrictions on water use imposed by these decrees were taken at the beginning of May when Morbihan was put on “vigilance” alert. This glaring comparison for one year can only be considered as one of the indices of the future multiplication of drought periods announced by climatologists. Fires devastated many forests this summer of 2022, mainly in Gironde. By the end of August, more than 62,000 hectares had burned across France. And Brittany, in the midst of a drought, was not saved from the fires. Specifically, Finisterre, where 2,588 hectares were destroyed in the Monts-d’Arrée this summer. To which are added several fires in Morbihan, in particular in the forest of Brocéliande. “For 20 years, the burned area in Brittany has been quite exceptional, reports Anne-Marie Treguier. The region is no longer protected from these phenomena that, in the past, affected the south of France more.” According to Vincent Dubreuil, geographer and climatologist, we are witnessing what he calls “the Mediterraneanization” of the climate in Brittany. Like Anne-Marie Tréguier, co-president of the Breton High Council for the Climate. This independent body, created last May, has the mission of contributing its scientific experience to public policies to combat climate change. Deregulation, a term that Vincent Dubreuil rarely uses. He prefers to talk about change “of which we have a concrete manifestation in Brittany, he says. For example, the number of hot days in Brest, i.e. more than 25 degrees, has increased by an average of 6 days a year after the World War II to 12 days a year for the last thirty years. In Rennes we’ve gone from 28 days to 45 days a year.” Rennes is La Rochelle or Bordeaux fifty years ago in terms of temperature Vincent Dubreuil Climatologist and co-president of the Breton High Council for the Climate The days of frost have decreased in both cities during the same period. In Brest, after the war, an average of 18 days a year froze, compared to 14 days in the last thirty years. In Rennes, the same scenario: the number of frost days dropped from 43 to 30 per year. “Rennes is La Rochelle or Bordeaux fifty years ago in terms of temperature”, analyzes Vincent Dubreuil. A planet that is warming as a result of greenhouse gas emissions produced by human activity, more intense and prolonged periods of drought, more violent and sudden rains… and rising sea levels, slow but sure, which results, on the Breton coast, in a retreat of the coast and the risk of submergence. “This is a problem identified as important in Brittany, points out Anne-Marie Treguier. Obviously, the rise in the level of the ocean is not perceptible like this. What we are going to perceive, for example, is a dock, flooded once every time. 3 or 4 years at the time of the high tide, which from now on will flood systematically. It is these kinds of remarkable episodes that set the trend.” To limit and stabilize global warming by 2100, “we must move from rhetoric to action,” says Vincent Dubreuil. According to the climatologist, “all the lost years will require even more effort to make up for them. The faster we act, the less abrupt the transition will be.”
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