LA TRIBUNE SUNDAY – What are the particularities of the Mediterranean that favor exceptional events like this?
YVES TRAMBLAY – First of all, it must be remembered that Mediterranean episodes like this remain common during this period. This is not an extraordinary episode in terms of rain intensity. Its mechanism is very simple: in the fall, the Mediterranean is still very warm, because it is relatively closed, leading to evaporation with air masses loaded with humidity which trigger these episodes of intense rain.
And, like the oceans, its temperature continues to increase, by 0.3 to 0.4 degrees per decade since the 1980s, and this phenomenon is not about to stop. The different scenarios project an increase of 0.9 to 5.6 degrees depending on the level of greenhouse gas emissions by 2100 compared to 1980. We must therefore expect episodes of increasing more intense.
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Can the Mediterranean be described as a time bomb?
I wouldn't use that term, because these episodes aren't new, they're just going to be much more common in many areas. Valencia therefore demonstrates that the effects of climate change can already be felt, in the same way as droughts, which will be more and more frequent.
Could such a phenomenon occur elsewhere around the Mediterranean?
There have been several episodes like this in the past. In France, we can think of Nîmes in 2002, of Aude in 1999. There is also what happened in Derna, in Libya, last year, which left at least 5,000 dead. These episodes are precursors of what will happen more and more frequently in the region.
Currently, the areas most at risk in the future are areas already affected, including coastal areas in Spain, northern Italy and southern France. In the Cévennes, which are part of the Mediterranean areas where there is the heaviest rain, we have already exceeded 700 or even 900 millimeters per day. It's huge. France is on the front line facing the increase in these episodes.
How can we fight against the multiplication of these events in the Mediterranean?
To limit this damage, it will be necessary, in the long term, to limit greenhouse gas emissions to avoid heading towards the worst. And in terms of adaptation, we should first develop forecasting systems to be more precise and alert the population. The second issue lies in the response of the populations. Compliance with safety instructions must be ensured. Today, many people die during floods because they drive, believing they are safe.
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Should other, more significant measures be considered to limit the damage linked to these floods?
We can hope that this tragic episode will serve as feedback to analyze the reasons why there were so many deaths and work on the strategies to adopt to limit the number of victims. This involves territorial planning, particularly urban areas, and knowledge of risk areas.
It should be considered that they be reorganized, or even abandoned. We see that in France there is already a certain awareness of the seriousness of these episodes. But in areas already built on risky land, this remains very complicated, because we cannot make the population move.
