Human-caused climate change has made extreme precipitation events that led to the devastating flooding in Valencia on October 29th 12% more intense and twice as likely. This is the result of a study by World Weather Attribution, which is still partial and likely underestimates the impact of the climate crisis.
Flooding in Valencia, WWA Study
This is not a full attribution study, like those typically produced by WWA. The analysis is based solely on observations, not climate models, and only on one of the three datasets normally available, the only one that was updated the day after the event.
Moreover, the result on the frequency and intensity of the extreme event refers to its impact on a very broad territorial scale. The return time for such an event is estimated to be around 20 years. On a more localized scale, for instance, in the areas most affected by the flooding in Valencia, the role of anthropogenic climate change is likely much more significant.
“We analyzed daily rainfall values over a relatively large region rather than sub-daily rainfall extremes that are more localized,” the authors explain. “This means it could underestimate the intensity of the most intense rainfall in specific regions.”
Over the 75 years covered by the available datasets, events with rainfall in 24 hours as intense as that of October 29th are about 12% more intense and have about double the likelihood of occurring in today’s climate, which is 1.3°C warmer than the pre-industrial climate and minimally influenced by human activity.
The impact of the climate crisis is just one of the factors that contributed to the heavy toll of victims and damage caused by the flooding in Valencia. By the morning of November 5th, in the Valencian community alone, confirmed casualties had risen to 211 (out of a total of 215), while search operations are still underway and an unspecified number of people remain missing.
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