Extreme weather events, caused or exacerbated by climate change, do not depend solely on the circulation of currents in the Earth's atmosphere. The sea also acts as "fuel" for both heatwaves and storms, hurricanes and floods. This is why the record reached off the Spanish island of Majorca, in the Mediterranean, is particularly alarming: temperatures hit 33.02 degrees Celsius, according to data recorded by a buoy belonging to the meteorological agency Aemet.

The agency specified that "the surface water temperature is more than 4 degrees above the seasonal average in the western Mediterranean and approximately 3 degrees above that of the Cantabrian Sea".

In 2024, temperatures nearly reached 32 degrees off the coast of Egypt

Excessively high water temperatures can not only prevent the cooling of air typical of coastal areas, but also supply the moisture needed to fuel extreme weather events, particularly following prolonged periods of heat.

In recent years, records in the Mediterranean have multiplied. In August 2024, in the waters off Nice, France, temperatures of 30 degrees Celsius were recorded. A few weeks later, thermometers reached 31.96 degrees Celsius off the coast of el-Arish, in Egypt.

"Repeated heatwaves," explains Luca Lombroso, meteorologist and science communicator, "affect not only air temperatures but also sea temperatures. In the Adriatic, temperatures have exceeded 30 degrees, and off the Balearic Islands they have surpassed 33 degrees: this is news that should worry us, especially looking ahead to autumn. It is in that season that we will pay the price for this situation."

Luca Lombroso: "With temperatures like these, we risk Medicanes this autumn"

According to the expert, "temperatures of this kind represent an explosive fuel: we are above the threshold at which hurricanes can actually form. Our saving grace is that the Mediterranean does not have tropical geographical conditions; however, this energy could transform ordinary weather systems into the close cousins of hurricanes — namely Medicanes — which can release enormous quantities of rainfall. This is the price of years of climate inaction."

Last 31 March, moreover, data from the European monitoring service Copernicus showed that the average temperature at the surface of the world's oceans exceeded 21 degrees Celsius — nearly 0.5 degrees above the average for the period between 1992 and 2022. At the same time, the National Oceanic and Atmospheric Administration (Noaa) had published similar data: the US agency reported a figure of 21.12 degrees Celsius, just below the all-time record set at the end of March 2024, when temperatures reached 21.16 degrees — and 0.57 degrees above the 1991–2020 average.

Data of this kind represent not only a source of discomfort for human beings and a risk of violent weather events, but also profoundly disrupt marine ecosystems. They affect the lives of aquatic fauna, strike coral reefs causing bleaching and death, and alter ocean currents.