As the century progresses, the Mediterranean will be an increasingly dangerous sea. With the global warming, it will look like tropical seas. These new conditions will facilitate the development of extratropical cyclones very similar to hurricanes, the medicanes. Although the different models and simulations indicate that there will be less, those that will be more durable, intense and carrying greater destructive capacity.
"Climate change is turning the Mediterranean into a more favorable environment for the development of hurricanes," says the researcher at the Institute of Environmental Sciences of the University of Castilla-La Mancha (UCLM), Juan Jesús González. It clarifies immediately that the term medicán or medicanes is a simplification and that in the Mediterranean they do not take place hurricanes like the tropical. First because it is not a tropical sea and, second, because they will never have the intensity and magnitude of a hurricane of category 3 to 5. "But they have the same physics," he recalls.
The medicanes are formed especially in the center and east of the Mediterranean. Unlike hurricanes, they hardly last a day, diluting in between 12 and 18 hours. Rarely its winds exceed 100 km / h and its dimensions are much smaller. In addition, the frequency of the medicanes is one or two a year, compared to the typical hurricane season that, in the Atlantic alone, usually exceeds 10 with as many tropical storms. But both live from the conflicting thermal interaction between the sea and the air. Both have this particular form of a spiral of swirling clouds turning counter-clockwise. And in one you can see the eye of the hurricane and in the other the doctor's eye.
The Mediterranean is becoming an increasingly tropical sea
All that is changing. A recent study carried out by a group of researchers with González at the forefront has modeled the appearance and development of medicanes in the context of climate change. The model has been developed by US scientists specialized in hurricanes and used for the simulation and prediction of hurricanes up to category 5. First they ran the model back, until 1985, seeing that it reproduced with great reliability the medicaments that appeared since then. Then, they chose the intermediate climate scenario that is expected for the rest of the century and they ran it into the future. They found good news and bad news.
"The frequency of medications will be lower," says the UCLM researcher. They are storms that reach the Mediterranean from the Atlantic and become tropical cyclones but, with global warming, "an expansion of the tropics and a translation in latitude of the subtropics is taking place, which implies that the storms will have more difficult to get there, "explains González. So the frequency will decrease, having years in which no medicine will appear.
But the rest of the conditions will be worse, that is, better for the medicanes. "Climate change is making the Mediterranean more tropical and the sea is the one that feeds a medicán", explains González. According to the results of his research, although the frequency could be reduced by 34%, the number of drugs lasting more than 24 hours will increase. "They can reach sustained winds of 125 km / h and gusts with higher speeds, which falls into category 1 of the hurricanes," estimates the UCLM researcher. The risk of a great medicine will be greater in the beginning of autumn and will be concentrated especially in the Ionian Sea, east of the boot of Italy.
With the longer duration and greater intensity of the winds, the so-called energy dissipation index will also increase and this is a measure that is related to the destructive capacity of these cyclones. "In addition, unlike hurricanes that tend to follow a predictable rectilinear route, the medicanes have more chaotic and irregular trajectories," González warns.
The destructive capacity of these cyclones is exponential to the increase of wind speed
"Their conclusions are similar to the results we have obtained," says Romu Romero, professor of meteorology at the University of the Balearic Islands, whose group has spent years researching the drugs. In 2017, and using a very different methodology supported in the generation of synthetic cyclones, estimated that, as in the work of the UCLM, there will be a reduction of these cyclones (between 5% and 10%), but, "when they are formed, they will be more intense," he adds.
In general terms, most will be weak, with some moderate and a few violent. The key here is the increase in winds, which have nonlinear effects on the intensity of the medicine. "The destructive power has a lot to do with the transport of kinetic energy: modest increases in sustained winds on the surface can exponentially increase its destructive capacity," recalls Romero. In its estimates, the Mediterranean will have medicanes that could contain winds of up to 140-150 km / h. For Romero, "with climate change, the probability of them entering category 1 [de los huracanes] it will no longer be despicable. "