The collusion of the two events would almost be a laughing matter if it weren’t so tragically revealing. While the film Don’t Look Up, which criticizes the widespread inaction in the face of climate change under the guise of wacky comedy, is a hit on Netflix, we are on the verge of having a barbecue at the end of December. And no one is shocked. Exceptional and localized episode? Obvious manifestation of global warming? Could this heatstroke have long-term consequences? So many questions that deserve to be asked. 20 minutes does it for you.
“The news is occupied by the health crisis”
The situation has enough to boil the chestnut trees. This year, no report on the Michut family, stranded on the road in Isère where they had to spend Christmas skiing, nor on Louis and Jeanne, two children who make a snowman in the Square Colbert. This year, the coronavirus is taking up all the space. “The news is occupied by the health crisis”, underlines rightly Nathalie Huret, director of the Observatory of physics of the globe in Clermont-Ferrand, questioned by 20 minutes.
Yes, but all the same. These abnormally mild temperatures should be of concern, right? In fact, this heat wave “does not represent an immediate risk for the citizen”, which explains, according to her, the absence of a strong reaction.
No landslide, precipitation that could overflow a river or, on the contrary, a dry water table, in short, nothing to move an executive in the midst of a “truce for confectioners”. The event was, however, well noted by climatologists: 13 ° C in the middle of the night in Lille on Thursday, up to 29 ° C in the Pyrénées-Orientales, not to mention “rain above 1,800 m in altitude in some stations in the Alps ”, reports Nathalie Huret. An exceptionally high rain-snow limit in December, not reached “before March-April in normal times”. “It is less impressive than a heat wave with two degrees more in summer, which is very serious in terms of health,” confirms Robert Vautard, climatologist among the authors of the latest IPCC report, also interviewed by 20 minutes.
Danger on agriculture
So, is this wave of sweetness just an inconsequential epiphenomenon? Not necessarily. To fully understand it, we must explain how it was created. “It is first and foremost an episode of meteorological origin”, explains the one who is also director of research at the CNRS at the Pierre-Simon Laplace Institute. A mass of air coming from the tropical zone of the Atlantic which “did not mix”, retaining its heat. In doing so, he helped push back the “polar vortex”, abounds Nathalie Huret, blocked above the pole. “It’s the entire meteorological system that is blocked,” she insists. A natural phenomenon, which has already occurred in February 2020, but where climate change “contributes to an increase in temperatures”, decrypts Robert Vautard. By boosting these temperature differences, climate change also contributes to their greater regularity, observable in statistics.
This mildness in France is not an isolated phenomenon, and it is in this that it is part of global warming, according to our two experts. But unlike a sudden flood, or even a heat wave that can lead to health actions, it is difficult to act to quickly bring back the cold. “There is a way to act, and that is to reduce greenhouse gas emissions”, smiles Robert Vautard. But it is not by releasing the pedal that the snow will fall. “It is a constant effort to stabilize the climate,” he proclaims.
If it is “one more indicator” of global warming for Nathalie Huret, this wave of mildness will not be without consequences in the medium and long term. With temperatures jostled compared to normal, all biodiversity is affected. “The pollinating insects will no longer wake up in the right phase,” she explains, believing that spring has come too early, when food is scarce. Or on the contrary, it’s the plants that can have the wrong timing. The flowering of certain species has already advanced by 15 days compared to the 20th century, suggests Robert Vautard. However, “plants in our latitudes need cold to develop well afterwards”, he recalls, also pointing out that they are exposed to frost by growing too early. Last year, a cold snap followed the mildness of March, causing losses of up to 30% in wine production. And for those who are still in T-shirts on the shores of the Mediterranean, sorry if we have cooled the atmosphere.