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Cyclones in the Mediterranean: we need "an alert system to displace the population"

In Libya, the number of casualties after Storm Daniel continues to rise. Authorities are now talking about at least 5,300 deaths. The mayor of the city of Derna, where entire neighborhoods have been swept away by the waves, fears up to 20,000 dead. Interview with David Faranda is a researcher in climate sciences at the CNRS and a specialist in extreme phenomena.

Damaged cars in Derna, Libya, after a cyclone hit September 12, 2023. © ESAM OMRAN AL-FETORI / REUTERS

By: Stefanie Schüler Follow

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RFI: The terrible destruction in Libya was caused by a "medicane". What is it?

David Faranda: A "medicane", for Mediterranean Hurricane in English, is a cyclone with tropical characteristics. The one we are talking about Libya strengthened on the Mediterranean Sea from the Daniel depression that had already affected Greece. Because of the very warm waters, 3 to 4 °C above normal, this cyclone had the energy to transform the heat and humidity of the atmosphere into rain that then flooded the coastal areas of Libya and caused the damage that was observed.

Is the formation of "medicanes" something usual in the Mediterranean?

We have about one or two a year, sometimes none. The last one that had already caused a lot of damage was a cyclone that had been named Apollo and that had hit Sicily in October 2021. In the past, we have also had "medicanes" that have affected Corsica, the seaside islands, Cyprus or Greece. We have known of these phenomena since the arrival of satellites. So "medicanes" have always existed in the Mediterranean.

Can we establish a direct link between this phenomenon and climate change?

Yes, we know that climate change does not change the frequency of medicanes. We are still expecting one or two "medicanes" per year to appear in the Mediterranean. But climate change is increasing the intensity of this phenomenon. Greenhouse gas emissions cause temperatures to rise, which also increases the temperature of the Mediterranean. Sea temperature causes more evaporation and warms the lower layers of the atmosphere. And all this energy that exists in the form of heat and humidity is available as soon as there is fresh air, as soon as there is a cyclonic zone forming to intensify the storms that are associated with cyclones.

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Which areas will be most exposed to "medicanes" in the coming years?

The most exposed areas are the most vulnerable areas from an infrastructure point of view. Some countries in North Africa as well as some countries in southern Europe do not have the infrastructure to cope with these amounts of rain or the coastal submersions caused by strong gusts of wind that accompany a cyclone. All coasts that are exposed to the east – not those to the west that are protected by prevailing winds – will have problems with Mediterranean cyclones in the coming years. These phenomena will be more and more intense. Because CO2 emissions will continue to warm the atmosphere of the Mediterranean, which will therefore have more energy, more heat and more humidity to create more intense cyclones.

What are the most urgent measures to take to bring people to safety?

If the amounts of rainfall that have fallen in North Africa are obviously exceptional amounts for the region, we can certainly design dams capable of withstanding these amounts of rain. It is also imperative to avoid rebuilding too close to coastal areas, but also to rivers. This is already the case in some countries such as southern France or northern Italy. The other essential thing is to set up an alert system, such as that of Météo France, which allows in the event of a cyclone to displace the population that is in flood-prone areas. We cannot avoid the extensive damage, but at least the thousands of deaths like those we deplore in Libya.

Read alsoSpotlight - Libya: what the images say about the unfolding of the disaster in Derna

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