The Med’s record temperatures increase the intensity of storms

The description of the Mediterranean Sea as soup is being mentioned repeatedly this summer on beaches scattered along the coast. Just stand on the shore to tune in and you’ll hear it. This soupy sensation is confirmed by the data. On August 15, the average surface temperature record for the Med was broken, reaching 28.47ºC, according to the Copernicus service, the EU’s Earth Observation Program, which also said that the longest period of average sea temperature above 28ºC has been being recorded since August 6. If last year was already extreme, the trend this summer has been even worse.

The sea is affected by marine heat waves, which are becoming more recurrent and intense as a result of global warming. While the rise in water surface temperature is drawing particular attention in the Med right now, for much of 2024 the average measurements for the world’s oceans in general have been out of kilter, setting off alarm bells among scientists. Until June, the average ocean surface temperature was setting daily unprecedented records.

Scientists consider this to be worrying for a number of reasons, including the fact that this heat on the sea’s surface is “fuel” for extreme weather events: storms or DANAs — isolated high-level depressions — such as those that have occurred recently in the Mediterranean.

To explain this, Sérgio Henrique Faria, a physicist and expert in atmospheric changes and professor at the BC3 Basque Centre for Climate Change, uses a boiling pot as an analogy in his lectures. “When you heat it up, the water is still and calm, but as time goes by, it starts to stir and you see more movement,” he explains. The increase in sea temperature works as an enhancer of atmospheric phenomena that makes them more damaging. It feeds them with energy. According to the professor, the process is as follows: hot water evaporates more easily and the air becomes more humid and warmer. Thus, when it collides with colder layers of the atmosphere, conditions are created that are conducive to the formation of more sudden and intense storms such as DANAs.

The greater the warming of the sea, the greater the concentrated energy and, thus, the greater the strength of atmospheric phenomena. “It is an important accelerator,” says the spokesman for the Spanish Meteorological Agency (Aemet), José Luis Camacho. The capacity of the sea to retain the absorbed heat must also be taken into account, he adds. “While the Earth shows a greater oscillation as it warms up more during the day but decreases at night, the sea accumulates and becomes a kind of heat reservoir,” he explains.

There is nothing new about storms in the Mediterranean. What has changed is the intensity with which they are happening, according to both Camacho and Faria. “It is an area where there has always been intense phenomena, but the increase in temperature causes them to have more available energy,” says Camacho.

In recent days, several storms have rocked the coast. It first happened in the Balearic Islands, producing images of boats tossed by the waves and masts skimming the water. Then it happened in the Catalonia and the Valencia regions, where strong winds and hail caused crops terrible damage after an extended period of drought. There were also extreme weather events in Sicily, which sank the luxury yacht on which the English multimillionaire Mike Lynch was travelling. Although there are no studies that confirm that the increase in sea temperature was the cause of these particular storms, experts warn that it may be a factor in exacerbating them.

Camacho flags up an additional problem in the area: the excess numbers of boats that are launched without taking into account Aemet’s warnings. “In the case of the Balearic Islands, the moorings are full and there are a lot of yachts anchoring in exposed areas. We gave the orange alert an hour before the storm struck after already giving the yellow alert, but there are so many people that the weather ends up catching someone,” he says. The Sicily scenario, which caused seven fatalities, was similar.

Impact on biodiversity

Beyond the external impact of rising sea temperatures, experts warn of the risk to marine biodiversity. One danger is acidification, a process by which seawater becomes more acidic due to the excess carbon dioxide it absorbs from the atmosphere. “The Mediterranean captures the carbon dioxide more easily, which is why it has a higher volume of it than the global average,” explains Faria. Camacho describes the situation on the Med as one of “stress.”

Current trends do not give much grounds for optimism. Camacho argues that, even if “we were to suddenly stop emitting greenhouse gases, the sea temperature would continue to rise, because the Earth has an inertia and the surplus of greenhouse gases would only be gradually reduced.” On a more positive note, Faria adds, “Every half-degree we manage to slow down greatly reduces the impact of extreme phenomena. We can’t reverse it, but it’s never too late to minimize it.”

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