Il preliminary report made by Arpae on the recent floods in Emilia Romagna1 dramatically brings to the fore the “new” phenomenon stirring in the depths of the Mediterranean, something that is challenging our certainties about the climate of this ancient sea. The Mediterranean tropical cyclone, once considered a rare anomaly, is becoming an increasingly tangible and worrying reality. The phenomenon, which combines the ferocity of tropical cyclones with the complexity of Mediterranean weather systems, is attracting the attention of scientists and coastal communities. But how does a Mediterranean tropical cyclone form? And what does it tell us about ongoing climate change? Let's enter the vortex of this “new” storm, where science collides with the unpredictability of evolving nature.
The enigma of the Mediterranean tropical cyclone
Il Mediterranean, a semi-enclosed basin nestled between three continents, has always had a unique meteorological character. But in recent decades, something has changed. The Mediterranean tropical cyclones, also known as “medicanes” (Mediterranean hurricanes), are emerging as a new climate challenge. These hybrid systems combine characteristics of tropical cyclones and extratropical depressions, creating an unprecedented meteorological phenomenon in this region.
The birth of a Mediterranean tropical cyclone is a complex and fascinating process. It all begins when a cold air mass at high altitude settles over the relatively warm waters of the Mediterranean. This thermal contrast creates instability, favoring the development of intense convective currents. If the conditions are favorable, the system can assume a structure similar to that of a tropical cyclone, with an eye in the center surrounded by bands of intense precipitation.
It took years of observation and study to fully understand this phenomenon. French and Italian researchers played a key role in this discovery. Their research, published in major scientific journals, have shed light on these extreme events, highlighting how climate change is altering the atmospheric dynamics of the Mediterranean.
The role of climate change
Il global warming is playing a crucial role in the evolution of Mediterranean tropical cyclones. With rising sea surface temperatures, the Mediterranean is becoming an increasingly favorable environment for the development of these systems.
The Mediterranean is warming up at a rate 20% faster than the global average. This creates conditions increasingly similar to those of tropical seas, favoring the development of extreme phenomena such as medicanes.
Le climate projections suggest, as mentioned, that their intensity could increase. This scenario poses significant challenges for the Mediterranean coastal regions, which could face increasingly violent weather events.
Anatomy of a Mediterranean Storm
How exactly does a Mediterranean tropical cyclone form? The process is a delicate ballet of atmospheric and oceanic factors. It all begins with an extratropical depression that moves over the Mediterranean. If it encounters sufficiently warm waters (generally above 26°C) and finds favorable atmospheric conditions at altitude, it can begin to develop tropical characteristics.
Il Prof. Silvio Gualdi ofNational Institute of Geophysics and Volcanology explains: “The process of ‘tropicalization’ can last from a few hours to several days. During this time, the system develops a warm core and begins to extract energy from the sea, much like a tropical hurricane.” As the system intensifies, it develops an eye-like structure, surrounded by intense bands of precipitation. Winds can reach hurricane speeds, although generally over a more limited area than classic tropical cyclones. The small size of these systems, however, does not diminish their danger.
Mediterranean tropical cyclone, the impact on the coasts
The arrival of a Mediterranean tropical cyclone can have devastating consequences for coastal areas. Heavy rainfall can cause flash floods, while strong winds and high waves can cause coastal erosion and damage to infrastructure.
Il Cyclone Ianos, which hit Greece in September 2020, is a clear example of this destructive potential. With winds reaching 120 km/h and rainfall exceeding 200 mm in 24 hours in some areas, Ianos caused extensive damage and unfortunately also casualties.
“These events remind us how important it is to improve our forecasting and warning systems,” underlines the Dr. Andrea Buzzi of the CNR-ISACThe hybrid nature of a Mediterranean tropical cyclone makes it particularly difficult to predict with traditional weather models.
The challenge of prediction
Accurately forecasting Mediterranean tropical cyclones presents a significant challenge to meteorologists. Their hybrid nature and relatively small size make them difficult to capture in global weather patterns.
To address this challenge, researchers are developing high-resolution models specific to the Mediterranean. The project Med-CORDEX, which involves scientists from across the Mediterranean region, is working to improve our understanding and forecasting capabilities of these extreme events.
“We are making significant progress,” says the teacher. Piero Lionello ofUniversity of Salento. “The new models allow us to more accurately simulate the interaction between the atmosphere and the sea, which is crucial for the formation of medicanes.”
The Future of Mediterranean Tropical Cyclone Prevention
Looking ahead, scientists predict that Mediterranean tropical cyclones will continue to evolve in response to climate changeTheir frequency could increase due to less favorable atmospheric conditions, on the other hand their intensity could increase, fueled by warmer waters.
This scenario poses significant challenges for the Mediterranean coastal regions. It will be necessary to adapt infrastructure, improve early warning systems and educate the population on the risks associated with these extreme events. International cooperation is also very important. The Mediterranean is a shared sea. Addressing the challenge of Mediterranean tropical cyclones will require a joint effort by all countries in the region.
Bottom line: We are sailing in uncharted waters.
Mediterranean tropical cyclones represent a new chapter in the meteorological history of the Mare Nostrum. They are the tangible result of how climate change is reshaping the face of our planet, transforming even historically “quiet” basins like the Mediterranean into arenas of extreme weather events.
The challenge ahead is twofold: on the one hand, we need to continue studying and understanding these phenomena, improving our forecasting and risk management capabilities. On the other hand, we need to step up efforts to mitigate climate change, the driving force behind the evolution of these extreme events. How can we better prepare for this new climate reality? And what lessons can we draw from the emergence of Mediterranean tropical cyclones for other regions of the world? These are questions we will need to find answers to in the coming years, as we navigate the uncharted waters of climate change.
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- The report first describes the amounts of rainfall generated by the Mediterranean cyclone Boris, which were greater than those of each of the consecutive events that affected the same territories in May 2023. The maximum cumulative rainfall during the entire event was recorded in San Cassiano sul Lamone, with a total of 360 mm, of which 285 mm fell in just 24 hours on 18 September 2024. ↩︎
