The Iberian Peninsula is suffering its worst drought in 1,200 years, and the cause is certainly climate change due to human activity.
Since around 1850, the Azores anticyclone has behaved strangely. Increasingly, it becomes extremely large and diverts much-needed winter rain away from the Iberian Peninsula. This shift in the direction of the anticyclone means that the Iberian Peninsula is currently experiencing its worst drought in 1,200 years.
The cause of this drought is almost certainly climate change, found a working group led by Caroline C. Ummenhofer of the Woods Hole Oceanographic Institution, based on observational data and climate models.
According to the study published in the prestigious scientific journal Nature Geoscience, this persistent lack of rain is attributable to the Azores anticyclone, an area of ​​permanent high pressure over the North Atlantic that greatly influences Europe’s climate. For the last 250 years, this number has been increasing in winter, diverting winter rains from Spain and Portugal.
The rise of the Azores is one of the factors that control the trajectory of low pressure systems over the North Atlantic. In summer, its center tends to be close to Bermuda; in winter it tends to be in the western Atlantic, near the Azores. Under normal conditions, the low winter pressure zones that supply water to Spain and Portugal can pass north of this high pressure core towards the Iberian Peninsula. On the other hand, if the discharge is especially large, it diverts precipitation towards northern Europe and Scandinavia. According to the models, an oversized high pressure in the Azores reduces rainfall by about a third.
The dripstone data from the caves really shows that these years are exceptionally dry in the region. The team’s analyzes and climate simulations suggest that this is exactly what has been happening with increasing frequency over the past 250 years. Models suggest that there hasn’t been a comparable situation for at least 1,200 years, if not longer. Before 1850, that is, during the Holocene climate, which was not much influenced by man, these Azorean maximums occurred about once every ten years. In the following century, they occurred every seven years and, since 1980, every four.
REFERENCE
20th century Azores Unprecedented expansion in the last 1,200 years