France should reach, Monday, February 20, its thirtieth day in a row without rain, according to Météo-France, i.e. the number of days when the average precipitation over the whole territory did not exceed the marginal threshold of 1 millimeter . The rain had never deserted the winter for more than twenty-two days, a duration observed in 1989.
The maximum for all seasons – thirty-one days in the spring of 2020 – should not be exceeded. Indeed, precipitation is expected on Tuesday and Wednesday, in the west of the country and then on the shores of the Mediterranean. The rain will be life-saving but insufficient, according to Matthieu Sorel, climatologist at Météo-France, for “reload” soils and groundwater already dried up by a particularly dry summer and then autumn.
Is the current winter drought, never recorded for so long and so early in the year, a new symptom of global warming?
One thing is certain: this season is no longer an exception, it is just following many months characterized by marked rainfall deficits. Going back over a year, the last winter (−15%) already, then spring (−40%), summer (−25%) and autumn (−10%) had suffered from precipitation well below average seasonal. No time of year is now spared from drought.
Is the current phenomenon a direct result of global warming? It is too early to be sure, only an attribution study will be able to establish the causal link. If the origin of the episode still raises questions, its nature is clearly established: since January 21, a powerful anticyclone has taken up residence in the British Isles and northern France. This zone of high atmospheric pressure acts as a solid barrier to disturbances that no longer reach us.
What consequences can we fear for soils and groundwater?
This record is all the more worrying as it is recorded right in the “recharge period”, from September to March, during which precipitation should normally ensure the replenishment of groundwater. The charge typically stops in March: the vegetation then resumes its rights and begins to pump into these reserves the resources necessary for its development.
We can therefore already anticipate an impossibility, this year, to reconstitute the water stocks required for the summer, all in the continuation of the infernal cycle typical of global warming: insufficiently rainy autumns and winters no longer ensure food in water for spring and summer which, themselves extremely hot, need more and more water.
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