The Mediterranean Sea is fundamentally warming, corals and plants are dying out on a large scale, fish and crustaceans are migrating | World

The sea between Europe and Africa has shown “very significant temperature anomalies” since May, more than 70 days in a row, says Samuel Somot, a heat wave specialist at the French weather service Météo-France.

The situation is worst on the French Cote d’Azur, around the Balearic Islands, Corsica, Sardinia and along the Italian coast. On the contrary, the coast in the north of Africa remained relatively spared this year; in Greece and Egypt this year the sea is even colder than usual.

At Marseille, the sea is usually around 21.5 degrees Celsius at this time, this year it is 28 degrees Celsius. Near the Corsican city of Bastia, they repeatedly measured the water temperature around 30 degrees Celsius. Since 1993, the temperature of the Mediterranean Sea has risen by practically one degree Celsius, according to data from the European Copernicus system.

“These marine heat waves occur when there are long-term high temperatures, stable conditions, clear cloudless skies and moderate winds. Water on the surface of the sea is motionless and cold water from the depths has no chance to reach the surface. Corals, crustaceans and fish suffer greatly from this,” explains Rubén del Campo, spokesman for the Spanish National Meteorological Agency.

The sea usually functions as a regulator of the ambient temperature, in winter the water warms the air, in summer it cools it, but this function stops working this summer, especially during summer nights, warns del Campo.

“Current events in the Western Mediterranean are among the most extraordinary in recent years. This can be explained by the fact that two anticyclones are gradually coming from tropical Africa, which bring very hot winds that heat the atmosphere and then increase the temperature of the sea when there is no wind. However, the increase in the frequency of these heat waves is linked to global warming,” says Ronan McAdam, a researcher at the Euro-Mediterranean Center for Climate Change in Bologna, Italy.

For much of the underwater fauna and flora, current water temperatures are a harbinger of extinction. According to a study conducted in 11 countries around the Mediterranean Sea between 2015 and 2019, the results of which were published in the journal Global Change Biology in early July, there is a “massive die-off” of around 50 species from the Strait of Gibraltar to the Middle East. Marine heat waves will now be the norm rather than the exception, study says.

The first victims of the ever-accelerating effects of global warming are colonies of corals and posidonia, green grasses growing on the sandy seabed. These plants serve as a refuge from predators for young fish and have also absorbed 11 to 42 percent of the carbon dioxide that humans have produced since the industrial revolution, writes Le Monde, citing data from the World Wide Fund for Nature (WWF).

Sea heat also threatens other creatures that are pillars for the underwater life of other organisms. The heat is now also falling on the scaly sedge (pinna nobilis), which filters impurities dissolved in the water and serves as a habitat for approximately 150 species. David Diaz, a researcher at the Spanish Institute of Oceanography in Palma de Mallorca, compares what is happening in the sea to “underwater fires where fauna and flora die as if they were burned”. Corals and posidonias used to form cities, but now they crumble into villages, forcing the animals that are capable of it to leave.

A year ago, the WWF warned of the “tropicalisation” of the Mediterranean, where warming is progressing 20 percent faster than in other seas and oceans. As the temperature rises, new species of animals come into the sea and decimate the original vegetation. Scientists have so far recorded almost 1000 of them, of which 126 are fish. New species of fish that did not live here before feed on the larvae of native fish and crustaceans. This results in a complex transformation of the underwater fauna of the Mediterranean.

All scientists agree on at least one thing: the current revolution in the Mediterranean is out of control, concludes Le Monde.

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