Weather experts predict a repeat of 'Dana' that led to the Valencia disaster in around 20 years' time

A report by the World Weather Attribution organisation predicts that the 'Dana' that caused the most serious flooding in the history of Spain on Tuesday 29 October will be repeated in about two decades. The document reveals that the rain that fell that day is 12% more than would have been collected in a similar rainfall event before the 1.3 degree increase in the average temperature of the planet.

The study therefore supports the thesis that anthropogenic climate change can, and does, lead to more severe and therefore potentially more destructive events. The document, drawn up on 31 October, said that the rain was forecast on 25 October and that its severity was confirmed on the morning of the 28th. "Despite the predictions, many people in Valencia only received emergency alerts when the rain had already started and evacuation was not possible for many," it added.

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The report insists that what fell over Chiva was «an extreme event» and that it may take more than 20 years to happen again. In any case, with the data available to scientists, it is not possible to determine how infrequent these events are. The paper does note that days with this much water falling are twice as likely as before the 1.3C increase in global climate. "These results are based on observed data and do not include climate models that are used in comprehensive studies. However, the results are in line with existing evidence that similar events across Europe are signs of climate change. We are confident that changes in intense precipitation are driven by anthropogenic climate change," said the report authors.

The report also reveals that floods "are often triggered by heavy rainfall within a few hours". "Studies have shown that these less than one-day events are 20 per cent more common than more extreme downpours. Europe has recently experienced devastating floods with very high casualty counts. For example, 239 people died in Germany and Belgium in 2021. This underlines the urgent need to improve the early warning and rapid reaction systems that are vital to ensure that people are not at risk," said the World Weather Attribution document.

Meteorologists insist on flood management measures such as wetland restoration and increased efforts to address social vulnerabilities "to better protect the lowest paid and minority communities, who often live in high flood risk areas".

"This will also reduce the cost of human losses," say the experts in the report, which was produced in just 24 hours with data available the day after the flood, as is customary for the organisation, which studies extreme weather events around the world to draw initial conclusions.