Global warming quadruples the intensity of torrential rains in Spain

As temperatures rise in Spain due to global warming, destructive rains have become heavier. In half a century, the intensity of torrential rains has increased 4.5 times, according to data collection carried out by the Polytechnic University of Catalonia.

The power and consequences of torrential storms in Spain continue to illustrate the toll of this phenomenon resulting from the climate crisis. This week, one person died and another is still missing, washed away by the waters of a violent rain in the torrent Paris from Majorca. Last March, Storm Nelson caused four deaths. This is only the toll for 2024. Deaths from destructive storms can be traced from year to year. Just 12 months ago, in September 2023, a new episode of torrential rain caused six deaths. Storm Gloria of 2020 left 13 dead in its wake. A very violent and very localized storm caused the loss of 13 lives in Mallorca in 2018.

“The analyzes show an increase in these extreme weather phenomena over the period we are studying,” say the UPC researchers. The increase is “significant” both for episodes of very heavy rain – with more than 30 mm of rain – and for those of torrential rain – 60 mm or more – which, according to these calculations, show “an increase in intensity by 360%. since 1971.”

This work has clarified trends already described, for example, in AEMET documents, which explain how the data “indicate an increase in the frequency and intensification of situations that cause very heavy or torrential rains of magnitude significant throughout the Spanish territory. Mediterranean”.

Heat influences

Precisely, the half-century rainfall records studied by the UPC show that “episodes of very heavy rain are relatively widespread throughout the peninsula and the Balearic Islands”. As for the even more intense (torrential) rains, they have multiplied “in Andalusia, in Castile-La Mancha, in the Region of Murcia, in the Valencian Community, in the south of Catalonia, in the Balearic archipelago, in Aragon, Navarre and the Basque Country. The most intense areas are concentrated in particular on the Mediterranean coast.

In the context of global warming, researchers looked for the interaction between escalating temperatures in Spain and precipitation patterns. “The measured maximum temperature is the indicator that shows the greatest correlation between total precipitation and droughts,” they conclude.

And they add in particular: “In the event of extreme precipitation, the strongest correlation occurs with the minimum temperature measured. ” This means, they continue, that “the years that are warmest at night are those that show a stronger tendency for extreme precipitation.”

The most significant is that we are experiencing a climatic paradox because there will be more and more drought, but with precise moments when it rains, giving the impression that the sky is going to fall on our heads.

Joseph Roca
— Researcher at the Polytechnic University of Catalonia

It is precisely the intense heat that triggers nights with unprecedented temperatures due to their height. Tropical nights (with 20°C) have become normal and so-called torrid nights (+25°C) have increased sixfold since 1980, according to AEMET.

“The most significant thing is that we are experiencing a climatic paradox because there will be more and more drought, but with precise moments when it rains, giving the impression that the sky is going to fall,” explains one of the authors. . of the study, Josep Roca.

Because the other side of the coin is that precipitation in general is rarer in the peninsula and the Balearic Islands. During the same study period, a decline in total precipitation of 8.9% was observed. This shift towards a drier Spain with higher temperatures is what led this research team to calculate that at this rate, in just a few decades, the majority climate will become steppe rather than Mediterranean.

Without change in the transformation trend, the typically Mediterranean climate would go from 24.43% of the peninsular and island territory in the reference period 1971-2000 to 10.13% in the period 2040-2060. A whole expansion of what they call “brown” Spain.