Drought and heat are hitting Spain and Portugal hard. And we know (somewhat) why. The Azores anticyclone, which has grown, is this area where the atmospheric pressure is higher than average.
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Located around the archipelago of the same name in the Atlantic, it plays an important role in the weather throughout Western Europe, in particular by directing the rains towards the north of the continent.
The expansion of a high pressure system over the Atlantic — the Azores High — is leading to the driest conditions on the Iberian Peninsula in the last thousand years, according to a modeling study published in @NatureGeosci: https://t.co/HKGVUsvol1
—Springer Nature (@SpringerNature) July 5, 2022
However, by studying the changes in atmospheric pressure in this area over the past 1,200 years, American researchers have found that the anticyclone has tended to widen, especially over the past 200 years. In other words, since the beginning of the industrial revolution. They also establish a link with the increase in greenhouse gas emissions over this period.
The link between the widening of this anticyclone and the current drought has been made with the general trend of reduced rainfall volume over Spain and Portugal, especially in winter. This trend – historical – is more marked since 1950. To reach its conclusions. the researchers then combined different measurements: both meteorological readings, computer simulations and also the study of stalagmites in a Portuguese cave. By observing the chemistry of these mineral columns, it is indeed possible to identify periods of drought or intense rains several centuries back. Another conclusion of this American study published in Nature Geoscience : the level of this precipitation should drop by another 10 to 20% by the end of the century over Spain and Portugal. An increased drought which could threaten the cultivation of olives in the South of Spain, as well as that of the vine.
The strengthening of this Azores anticyclone does not have, at this stage, a huge influence on France. Overall, we expect slightly drier summers, and slightly wetter winters in the North. But we are less affected by these changes than the Iberian Peninsula, which is drying out, or the United Kingdom, which risks receiving a little more rain in winter.