The weather continues to claim victims. In Spain, in the Valencia area, the amount of rain expected in a month fell in 24 hours (in some municipalities, that of an entire year), with dramatic consequences: 70 deaths (confirmed), thousands of people isolated and stuck at home, cities flooded and piles of wrecked cars piled up in the streets.
Water apocalypse over Valencia, dozens dead and missing
A catastrophe that actually represents the long tail of the atmospheric phenomena that have affected our country in recent weeks, causing damage and flooding in Emilia Romagna. And unfortunately, it’s something we’ll have to get used to in the future, because climate change makes such extreme weather events more common and, above all, more powerful and destructive.
La Dana in Spain
The meteorological phenomenon that hit Spain is known as the “cold drop”, or by the (more recent) acronym of Dana – Depresion Aislada en Niveles Altos, or isolated depression in the upper levels. It occurs when a cold air mass at altitude isolates itself from the main flow, forming a closed, quasi-stationary depression. This configuration generates a strong contrast with the warm and humid air present at low altitudes, triggering intense thunderstorms and heavy rains, which tend to remain for long periods in the same area, therefore being more destructive.
This is a weather event characteristic of the Western Mediterranean and French territory, and its arrival on the Spanish coasts, typical of the summer and autumn months, had been predicted by meteorologists. However, no one had been able to predict its intensity.
On October 29th the amount of rain expected in a month fell on average in the Valencia area, with peaks confirmed by the Spanish meteorological service exceeding 200 millimeters (compared to a monthly average which in this period is around 65 mm) in the town of Utiel, and a record to be confirmed in Chivas, where we are talking about 491 mm in eight hours, equivalent to the water that normally falls over the course of an entire year. According to the Spanish meteorological service, this is the worst storm to hit the country in the last 60 years, comparable to the two major events of the 1980s (1982 and 1987) which caused dozens of deaths and extensive damage.
If the phenomenon itself is therefore not new, we will have to get used to seeing weather events with ever greater intensity more and more often. The intensity of the rainfall associated with a Dana depends in fact on the temperatures of the lower layers of the atmosphere and on the availability of humidity (it is no coincidence that it is particularly strong at the end of summer and in the autumn months), and with global warming which continues to increase average temperatures (2023 was the hottest year since records began), especially in our Mediterranean, the torrential and destructive rains associated with Dana phenomena, but not only that, will be increasingly frequent.
Floods in Italy
The Spanish catastrophe comes just over a week after the one that hit our country. And it is no coincidence: as meteorologist Francesco Nucera explains on 3Bmeteo, the Spanish Dana was caused by what remains of the low pressure that produced the floods of recent days in Italy, and which remained isolated between Spain and North Africa at due to the increased pressure on the rest of Europe.
Even in Italy, the low pressure area was found to be stationary, and fueled by humidity and high temperatures, it produced heavy rainfall which was concentrated for a long time in the same areas of Emilia Romagna, causing the damage we have seen. Between Saturday 19th and Sunday 20th October, more than 160 millimeters of rain fell in Bologna in less than 24 hours, also in this case, a quantity of water greater than that which is normally seen falling in the space of a month. What also complicated things, in this case, was the fact that the downpour came at the end of a month that had already proved to be particularly rainy, and therefore found the soil already saturated with water and therefore unable to absorb any more.
In the Italian case, as in the Spanish one, it is extremely complex to attribute a meteorological phenomenon to the direct action of climate change. In short, to say how things would have gone if our species hadn’t had a hand in it. However, it is almost proven that global warming tends to increase the frequency, and above all the intensity, of extreme precipitation, because with the increase in temperatures the humidity present in the air increases, and there is therefore more fuel to fuel the power of phenomena such as the Dana. And this is why unfortunately we have to expect similar catastrophes with an ever-increasing frequency. And that all we can do, at this point, is try to be ready for next time.
Within 20 years, extreme weather will be a problem for three-quarters of humanity