Winter 2022-2023 presents temperature anomalies: the weather is too mild compared to seasonal norms. A phenomenon linked to climate change. An ecologist explains how an overly mild winter affects certain plants and therefore our food.
The transition to 2023 was made under the sign of climate change: this winter is one of the mildest recorded in France, accumulating many records. The consequences are multiple. Beekeepers, for example, alerted : the bees behave as if it were already spring. Similarly, the danger is to see certain crops blooming too early… at the risk of them being destroyed by frost afterwards, with no opportunity to bloom again before the next season.
But in a detailed thread, French ecologist Sophie Leguil alerted on January 5 to a related subject, much less often discussed: the impact of temperatures that are too high (too mild), compared to seasonal norms, on the fruits that we will eat at spring and summer; and on many plants more generally.
Cold is essential for flowering
Sophie Leguil evokes a phenomenon called vernalization: the cold period — a temperature below 7 degrees (but without frost) — thanks to which certain plants flower. Yes, “grace”. This period allows the transition between the vegetative stage and the reproductive stage. ” In winter, the buds are in the so-called dormant phase. Researchers have determined that a certain number of cold hours are needed to allow a transition to flowering », explains Sophie Leguil.
The ecologist details the genetic process at work:
- The Flowering Locus C (FLC) gene prevents flowering;
- Cold ” induces accumulation of VIN 3 protein (the required accumulation varies from one species to another, which is why the number of hours of cold required varies);
- The VIN 3 protein inactivates the FLC gene (ie it can no longer be expressed temporarily);
- Once the FLC gene is inactivated, flowering is possible.
This is where the temperature anomaly that takes place during this winter is problematic: the impact on vernalization could cause anomalies in the development of certain plants, and therefore of their fruits; but also a logout between pollinators and flowering. Possible impacts catastrophic writes Sophie Leguil.
Winter too mild: hard blow for food?
Among the possible consequences on plants affected by staggered vernalization: “ Abnormal flowers, for example (double pistils, too short pedicels) or flower drop, which obviously affects the yield. This can change the shape of the fruit. Added to this list are the risks of seeing the development of fungi and insect pests affecting the good health of the fruit in question.
And, as Sophie Leguil points out, this is not without consequences for consumers: “ A [augmentation] potential for the use of pesticides, a surge in the price of fruit, a decline in food self-sufficiency since we are forced to import. »
And, the problem is that in a context of climate change, the episode of this season is neither the first nor the last. Like the drought during the summer, this can lead to increasingly severe shortages.
The solution ? First of all, the obvious: mitigating climate change as quickly as possible by significantly curbing emissions. But there is also adaptation: it will probably be necessary to change the production area, as well as the type of production, towards varieties requiring fewer cold days or towards greenhouses where the temperature is “forced”. Obviously, it would be preferable to avoid the use of chemical products in compensation, or the solution would be as problematic… as the problem.
” Will we still be able to enjoy the same abundance of fruits (and their by-products!) in 100 years? Hard to say. But what is happening shows the importance of 1) research (climato, phenology, agronomy) and 2) the conservation of varieties (old or not) concludes Sophie Leguil.
Sophie Leguil regularly offers science popularization threads, in rebound to the news and on subjects of our daily life, on his Twitter account.
