Ten facts to understand the extreme weather events of the last 30 years in Catalonia

BarcelonaCatalonia is now a warmer and drier country than it was 30 years ago, according to the Climate Atlas of Catalonia, an essential reference tool not only for meteorology and climatology enthusiasts, but also for many economic and social sectors that need to incorporate a climate perspective into areas such as agriculture and health, especially in this context. The headquarters of the Department of Territory, Housing, and Ecological Transition was chosen as the venue this Thursday to present the printed version of the Atlas, which covers the period 1991-2020 and provides a highly representative and well-defined picture of the changes that have occurred in the last three decades. Specifically, this document confirms that Catalonia has warmed by approximately one degree Celsius—a rate much higher than the rest of the planet—the semi-arid zone of the territory has expanded westward, and autumn has become the rainiest season across almost the entire region.

Marc Prohom, head of the Climatology Department at the Meteorological Service of Catalonia (Meteocat), highlighted that the region already had its first rainfall atlas during Meteocat's initial existence nearly 100 years ago, and that updating these publications "allows us to understand the pace and impact of climate change, a valuable educational and scientific resource." For his part, Jordi Sargatal, Secretary of Ecological Transition (and renowned ornithologist), cited changes in bird migration patterns as an example to demonstrate the importance of studying climate change. This atlas, which uses the years 1991 to 2020 as its reference and study period, replaces the previous one, covering the period 1961-1990, and some of its components were already published in the autumn of 2023. The novelty of this atlas lies in its inclusion of climatic variables, such as absolute maximum temperature, frost days, tropical nights, and the maximum duration of a dry spell (number of consecutive days with less than 1 mm of precipitation).

Having this data "allows for improved risk planning and management," according to Sarai Sarroca, director of Meteocat, since studying and having detailed maps of the frequency, duration, and intensity of phenomena such as torrential rains or frosts has practical applications in flood risk management or in assessing the potential impact of cold weather.

Very heavy rains

In a week marked by flooding in areas like Falset, Alcanar, and Badalona, it's noteworthy that nearly 80% of the country experienced rainfall exceeding 100 mm in a single day during the study period. This illustrates that virtually any location in the territory can be impacted by episodes of very heavy rainfall. In fact, the highest recorded value during this period was 287.2 mm on October 9, 1994, in Cornudella de Montsant (Priorat), near Falset, where 213 mm fell on Monday. The inclusion of unique climate zones, such as the high mountains and Els Ports, in the meteorological data atlas has allowed researchers to establish that this massif in the far south of the Principality is the area with the most days of heavy rainfall, with nearly six days annually exceeding 50 mm. In fact, they average over 1,000 mm annually, still far from the 1,500 mm recorded in some high mountain areas of the Pyrenees.