The recent floods that are devastating Spain, especially in the southern and eastern regions, are caused by the meteorological phenomenon known as Dana. This phenomenon occurs when a prolonged accumulation of cold air forms a depression that interacts with warm air masses. In Spain, this event has manifested itself with great intensity, similar to what happened in previous weeks in Northern Italy, now moved westward. Gianni Messeri, meteorologist at the Lamma Consortium, explains that “it is a depression circulation already observed in the past”. The cold air that is found at high altitude remains isolated and generates a closed depression, which is particularly dangerous because it can remain in the same place for a long time; this means that the Spanish regions will continue to be affected by this situation in the coming days.

Spanish climatologists report that similar weather events to those in Valencia have occurred in the past, but the current intensity is unprecedented in the last hundred years. Antonello Pasini, a climate physicist at the CNR, highlights the uncertainty regarding the possible link between global warming and the frequency of extreme events; however, it is certain that their violence has increased. Regarding the Valencia flood, Pasini clarifies that it was caused by what is called a “cold drop”, a term used to describe a depression with cold air inside it that detaches itself from the predominant air flows.

These events are not rare, but their intensity is increasing due to global warming. The researcher also states that the stronger the thermal contrast, the more violent these phenomena become. With climate change, the Azores anticyclone is giving way to warmer African anticyclones. This leads to an increase in evaporation and the availability of water vapor in the atmosphere. Warmer sea waters provide additional energy, and ultimately this vapor and energy translate into intense precipitation and strong winds.

Andalusia, a traditionally dry region not prepared for heavy rains, has already faced droughts this summer. Rainfall, when it falls on dry land, is not absorbed effectively.