Why were the Valencia floods so deadly, did the warning messages come too late and what is the link with the climate?

At least 158 ​​people were killed in the south and east of Spain following sudden and deadly floods.

This figure is expected to increase as searches continue for dozens of people still missing, some regions have not yet reported their victims and Further rain is forecast in some of the worst-affected parts of the country.

In some regions, precipitation equivalent to a year's worth of rain fell in just eight hours on Tuesday. The Spanish National Meteorological Agency (AEMET) indicates that in the Chica region, in Valencia, 491 liters per square meter accumulated in eight hourswhich is “extraordinary”.

Inundated by deadly waters, people were trapped in their homes, cars were swept away and bridges were ripped from their foundations.

“This is the dramatic reality of climate change,” European Commission President Ursula von der Leyen said on Wednesday, adding that extreme weather events have become the “new normal.”

“We must prepare to face it, across the Union, with all the tools at our disposal.”

“There is no doubt that these torrential rains have been intensified by climate change”

“THE images and videos from southeastern Spain show the power of water at its finest,” says Linda Speight, senior lecturer at the School of Geography and Environment (SoGE), University of Oxford.

“Unfortunately, these events are no longer rare. Climate change is changing the structure of our weather systems, creating conditions where intense thunderstorms stop over a region, leading to record rainfall – a pattern we are seeing repeatedly”.

Climatologists and meteorologists have attributed the flooding to what is known as a “low pressure storm system” which migrated from an exceptionally wavy and blocked jet stream. This system then stalled over the region, dumping a year's worth of rain in eight hours.

This is a natural weather phenomenon that usually affects Spain in autumn and winter. This phenomenon is so common that it has its own acronym: DANA (Isolated Depression at High Levels, Isolated depression at high levels).

THE unusually high sea surface temperaturesmade much more likely by human-caused climate change, and a warming atmosphere, have a direct impact on the amount of rain these storms can hold.

“There is no doubt that these torrential rains have been intensified by climate change,” explains Friederike Otto, head of the World Weather Attribution program at the Center for Environmental Policy at Imperial College London.

“Each fraction of a degree of warming from fossil fuels allows the atmosphere to hold more moisture, leading to heavier rain. These deadly floods remind us once again how dangerous climate change has become with a warming of only 1.3°C.”

Mr. Otto points out that just last week, the United Nations warned that the world was on the verge of a warming of 3.1°C by the end of the century.

“During the COP29, world leaders really need to agree not only on reducing, but also on stopping the burning of fossil fuels, with a deadline. The longer the world delays replacing fossil fuels with renewable energy, the more severe and frequent extreme weather events will become.”

Could Valencia have been better prepared for extreme weather events?

Local authorities have been criticized for not having issued timely warnings about the potential dangers of the storm.

The Valencia government admitted it only sent text messages warning residents of the disaster eight hours after the floods were reported and ten hours after AEMET issued a warning of “extreme danger” in the region.

This brief message sent just after 8 p.m. Tuesday arrived too late for many people who were already stuck in their homes, in stores or in their cars on the streets when the deadly floods hit.

Hannah Cloke, professor of hydrology at the University of Reading, said it was “dismaying” to see so many people dying in floods in Europe, despite forecasters predicting extreme rainfall and issuing warnings.

“The tragedy of people dying in cars or being swept through the streets is entirely avoidable if people can be kept out of rising waters. This suggests that the hazard warning system floods in Valencia failed, which had fatal consequences.

“It’s clear that people simply don’t know what to do when they encounter flooding or hear warnings.”