Winter mildness: what consequences for ecosystems?
The observation is clear: the year 2022 was the warmest on record in France, and this early winter saw record temperatures for the season. Because this mildness largely affects natural cycles, there is cause for concern for some wildlife species and ultimately for all ecosystems. If the phenomenon is only in its infancy, 30millionsdamis.fr reminds us how urgent it is to act.
Even though the mercury dropped sharply and it started to snow, France – like the rest of Europe – experienced a “winter heatwave” which gave the end-of-year celebrations and this beginning of January false airs spring. As proof, from 21 to 31 December the average temperature recorded is slightly higher than that previously observed in the first week… of April! What disturbs many animal species.
The “desynchronization” of flowering and wintering of pollinators
If the first organisms affected by this perturbation are obviously plants, animals also suffer the consequences. Insects – in particular – are generally “ectothermic” animals, i.e. they do not produce their own heat (like mammals for example) but adapt their lifestyle, even their physiology to the ambient temperature. So bees. If wild species go into “diapause” (reduction of metabolic activities to consume less energy and survive the winter), honey bees “hibernate”. That is, they remain active, but only within the hive, which is organized in such a way as to survive the drop in temperature. As soon as the latter rise permanently, they come out again to feed. In other words, honey bees are “in sync” with plant cycles. But if they haven’t had time to flower yet, or they started budding due to high temperatures but a return to a cold winter killed those buds, they may not have flowered by the time the bees emerge. These, therefore, will not have enough food and the entire colony could become extinct.
Even “warm-blooded” animals are in difficulty.
This desynchronization affects other species, including “homeothermic” animals, such as the hummingbird. It migrates in winter, to overwinter in more favorable areas, and then heads north. There, it will resume its nectar foraging. Only, if the winter is too warm, the flowers will come out early. But the hummingbird detects the arrival of good weather not by the temperature, but by the length of the day. Which is not affected by global warming. As a result, he may run out of food when he needs it most… and die.
This is also generally the case for migratory birds, which may therefore find themselves “out of sync” with their food sources (insects in general), which come out of their diapause earlier. The return migration (usually in spring) requires a lot of energy and no longer coincides with a period of great abundance, resulting in excessive bird mortality.
Mammals (homeotherms) can also be affected, depending on the factors that trigger their hibernation. If bears, for example, are not “true” hibernators and wake up (and act) several times during the winter, this is not the case for other animals such as hedgehogs or marmots. Thus, the elements that trigger hibernation in the hedgehog are many, but the external temperature is a component. Therefore, abnormal warming followed by cooling could impact his winter sleep and thus interrupt his cycle. However, hedgehogs, like all hibernating animals, on the one hand have to spend a lot of energy to get out of it, on the other hand they are very weak when they come out of hibernation.
Are the species doing well… for the worse?
Other animals – on the contrary – are favored by mild winter temperatures. Their diapause is shorter, allowing them to be active for a longer period of the year. Which is not necessarily good news: some of these species are “parasites”, such as bark beetles (a parasite of spruce), which therefore cause greater damage. We can also mention the mosquitoes, which can be present all year round if the temperatures don’t drop enough. With the known effects related to their proliferation.
Obviously, it is not only this “winter heat wave” that can produce these consequences, but the succession of “abnormal” temperatures (compared to the averages of previous decades) which, by dint of weakening ecosystems, can end up destroying them en masse.
However, the year 2022 was, in terms of temperatures, the one of all records, in France as elsewhere.
At present, the scientific community is still reserved on the effects to be expected, as it generally is on the impacts of climate change on biodiversity. But he expresses his concern quite unanimously. It is therefore urgent to take action to fight global warming, a fight that animals… and humans desperately need!
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