All summer long, off our coasts, the sea has stored the heat we’ve dumped into it, delaying the energy transition that scientists have been calling for as indispensable and urgent for decades . For many years, the oceans have offset our mistakes by reducing the thermal impact. Now, however, that balance is being disrupted. The figures from the LaMMA-CNR Consortium, updated at the end of August, reveal a record we would have gladly done without. In the Mediterranean, July was the hottest month since 1993, with an average surface temperature of around 27 degrees. Off the coast of Tuscany, the monthly average reached 27.7 degrees: 3.9 degrees above the 1991–2020 norm, the highest value in 45 years of record-keeping.
A warmth that penetrates deep
This is the peak (for now) of a trend that shows no signs of slowing down: the Mediterranean is warming by about 0.7 degrees every decade, and 94% of the basin has exceeded the 1993–2022 average ( data from Copernicus Marine and NOAA satellites). And the real news lies beneath the surface. In the Ligurian Sea, the average temperature anomaly between 0 and 70 meters is about +1.7 degrees, and remains close to +0.8 degrees at a depth of 70 meters. Translated into energy, the figures are staggering: “This excess heat corresponds to about 8.2 exajoules, which is 1.8 times the energy available for final consumption in Italy in 2024,” explains Francesco Meneguzzo, a researcher at CNR-IBE and commissioner of the LaMMA-CNR Consortium.
What happens to all this energy? The atmosphere absorbs it in the form of heat and water vapor in the lower layers of the air. It is the fuel for extreme weather events. Warm ocean water alone does not “trigger” a storm. For the trigger to be set off, something is needed to push the moisture-laden air upward, so that as it rises, it cools and condenses into clouds: this push can come from the collision of different air masses. But when the trigger does occur, it finds a much more abundant supply: more water vapor, more energy, and more potential intensity in the rain and wind.
And, of course, this isn’t happening only in the Mediterranean. In late August, The Guardian reported on what’s happening in the Yellow Sea, off the coast of South Korea: surface water temperatures have been several degrees above average for weeks, and storms emerging from the sea have grown stronger, bringing more devastating rains and violent gusts. The Korean Meteorological Administration points to the causes: reduced upwelling of cold water and a persistent high-pressure system, which has kept the warm air trapped over the region.
Copernicus forecasts
What will happen in the coming weeks? The Copernicus Climate Change Service, in its August 10 update for the September–November quarter, indicates above-average temperatures across much of Europe, including Italy, and a higher likelihood of precipitation in the southern and western parts of the continent. Seasonal estimates cannot go into the same level of detail as a precise forecast specific to a given time and place, but the trend is clear.
And there is a second driving factor: El Niño, which, according to NOAA, has a more than 90% chance of strengthening to “very strong” intensity over the next six months. Its effects on Europe are indirect, but they add another piece to a picture already brimming with energy.
An ocean that has absorbed a great deal of heat, an atmosphere ready to release it, and a worsening climate crisis. Fall 2026 begins with the reservoir full, and extreme events—when they occur—will be more intense than usual. Now is the time to remain vigilant, not to let our guard down. And perhaps it’s time to get serious about reducing the risk: greenhouse gas emissions from the overuse of fossil fuels and deforestation continue to rise.
