Following the record-breaking summer temperatures, extreme weather events in autumn

Following the record-breaking summer temperatures come the extreme events of autumn. This scenario – in which the warming of the seas and the significant build-up of heat also play a significant role – are the initial data for summer 2026 analysed in 6 of the 14 marine areas involved in Greenpeace’s ‘Mare Caldo’ project, which covers the Island of Elba and the Marine Protected Areas of Portofino, Miramare, the Tremiti Islands, Plemmirio and Ustica, ‘selected to provide a representative picture of the various sectors of the Italian seas’.

“From May 2026 onwards, several marine heatwaves occurred across all the areas under consideration, with peaks that in some cases exceeded the climatological average for the last 30 years by almost 5°C,” the research highlights. Sea surface temperatures last summer were approximately 1°C higher than the previous summer, with more intense and persistent events occurring between June and August.”

The highest peak was recorded on the Island of Elba, during a heatwave lasting 68 days, which caused surface temperatures to exceed the historical average by 4.95°C. Significant anomalies were also recorded in the Miramare Marine Protected Area in the Upper Adriatic, at +4.63°C, in the Portofino Marine Protected Area in the Ligurian Sea, at +4.36°C, and in the Ustica Marine Protected Area in the Strait of Sicily, at +4.54°C. The analysis, carried out with the scientific contribution of Riccardo Martellucci of the National Institute of Oceanography and Experimental Geophysics (OGS), integrated sea surface temperature (SST) data and model data (Med-Physics) from the Copernicus Marine Service, enabling the description of temperature trends both at the surface and throughout the water column.

According to Antonello Pasini, a climatologist at the National Research Council, ‘the summer we have just experienced was a “postcard from the future”: in the space of a single season, we have experienced what we may face repeatedly in about twenty years’ time’. ‘The heat that the Mediterranean is absorbing in ever-increasing quantities, unfortunately, does not remain in the sea,’ he emphasises. ‘The water that evaporates fuels the formation of clouds and rain, whilst the energy transferred to the atmosphere contributes to making weather phenomena more violent, with the formation of storm supercells, very strong winds, tornadoes or waterspouts – veritable tornadoes – and even so-called ‘Mediterranean hurricanes’. These extreme phenomena will be more likely this coming autumn, when a still-warm sea will amplify the contrast with the colder air and the weather systems arriving from higher latitudes.”

And against this backdrop, there is no shortage of problems for biodiversity. “The consequences of the high temperatures recorded throughout the Mediterranean are already visible on the seabed, where there are increasing signs of heat stress on gorgonians and corals, as well as the presence of alien and thermophilic species,” says Valentina Di Miccoli of Greenpeace Italia’s marine campaign. “The only way to slow down this process is to protect marine ecosystems through protected areas and drastically reduce greenhouse gas emissions into the atmosphere, which are fuelling the climate crisis.”