These are temperature records that are chilling for lovers of harsh winters. The end of 2022, and the first days of 2023, were marked by unprecedented temperature deviations from seasonal norms. According to Météo France, the national average was thus established at 13.3 degrees on New Year’s Day, or 7.6 degrees above normal. Such a difference has only appeared 25 times in the past 30 years, but occurred 6 times in 2022 alone…
However, this extreme mildness is not only synonymous with pleasant temperatures. For a nature, and an economy, which has developed on the alternation of hot and cold seasons, these temperatures are a major disturbance. “It’s not just about saving energy, we must not stay on a human-centered vision, man is not the only living being impacted by the climate, there are all the ecosystems and forests who suffer from it”, recalls Serge Zaka, doctor in agroclimatology at ITK, a company that models the impacts of climate on agriculture.
Increased vulnerability to freezing
One of the sector’s main fears is that these particularly mild temperatures encourage plants to bud too early. For a number of crops, such as fruit trees in particular, this mild winter may be the signal for spring. “The trees then begin to bud, that is to say that their buds open and this act is irreversible, which makes them very fragile when the frost returns”. The sensitivity of crops after these episodes is well known to farmers, in 2021 a vast wave of frost had caused more than 4 billion euros in damage in arboriculture and viticulture in France. And the phenomenon is getting worse.
“We have had much more devastating spring frosts in the last five years”, assures Serge Zaka, who adds that it is sometimes difficult to make people understand that the effects of this winter mildness can thus last until March or April. In addition, the heat during the winter can disturb the dormant period of the trees and reduce production.
These impacts are all the more important as it is difficult to cope with this type of climatic event. “In general, farmers stagger the sowing periods to avoid flowering during periods of summer drought, but in mild winters there are no miracle solutions”, underlines the agroclimatologist. One of the avenues for the arboricultural sector is to plant varieties whose flowering period arrives later, to avoid episodes of frost. A solution that is often difficult to apply in view of the investments that fruit tree plantations represent for periods of several decades.
Surplus of certain species
Crops are not the only ones impacted by the end of winter cold. With the shift, all ecosystems are turned upside down. “The life cycles of species are set either in relation to the seasons, or in relation to temperature or light, and when the temperature varies in an abnormal way, this shifts their periods of activity”, explains Colin Fontaine, teacher researcher at the Natural History Museum. This specialist in pollinating insects thus underlines the difficulty that the difference in temperature can represent with respect to the normal cycle of nature. “A good part of the plants need pollinators to reproduce, and they need to be activated by these flowers, there is a synchronicity during the seasons which can be turned upside down by these temperature differences”.
Elsewhere, such as in the mountains, the drop in snow cover is not only synonymous with the end of winter sports activities. The thaw at the end of December melted the snow on a good part of the ski slopes in France, and in the mountains the wildlife is also confused. “The rock ptarmigan – or snow partridge – for example, is white in winter, if there is no more snow it becomes very vulnerable to predators, because it can no longer camouflage itself”, testifies Maud Lelièvre, the President of the French Committee of the International Union for the Conservation of Nature. Conversely, the rise in winter temperatures can also cause population surpluses in certain species. Like the octopus, which has multiplied massively in recent years thanks to warmer water, less cooled in winter. “This can upset a food chain, because the octopus is a big consumer of scallops”, warns Maud Lelièvre.
Recurrence of these events
What is especially problematic, scientists warn, is the recurrence of such events, which adds to a nature already heavily degraded by human activities. According to Météo France, the difference observed on New Year’s Day is very rare, but the institution has observed an “upward trend in recent years”. “If we only had one episode like this, it wouldn’t matter, but it doesn’t, it’s not a phenomenon that will stop from one year to the next” , laments Maud Lelièvre.
According to projections by scientists from the Intergovernmental Panel on Climate Change (IPCC), global warming will lead to increasingly warm winters in Europe as global warming caused by human CO2 emissions increases. increases. And extreme weather events will thus become stronger, but also more recurrent. “The climate models that tell us that these events will replicate, but what will be the impacts of these increasingly warm and more frequent winters? For the moment, we don’t have the answer to that”, emphasizes Colin Fontaine.