Seas are increasingly warm, with heat waves reaching 40 meters underwater, with the highest temperatures in Sardinia.
The highest temperatures are at Capo Carbonara, Asinara, and Tavolara. The Greenpeace report: serious risks to life on the seabed.
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While 2026 has already marked an all-time record for global sea and ocean temperatures due to the climate crisis, the latest report from Greenpeace Italy's "Mare Caldo" project reveals that Italy's seas continue to warm , with heat waves up to 40 meters deep, coral necrosis or bleaching, and the increase in alien species.
The environmental association Greenpeace announced this, specifying that the report analyzes data collected in 2025 at 14 Italian monitoring stations, 13 of which are in Marine Protected Areas, with underwater thermometers and periodic monitoring.
In 2025, Greenpeace thermometers recorded prolonged episodes of high temperatures in all 14 study areas of the "Mare Caldo" project , even at depth.
"The Mediterranean is changing rapidly, and the effects of warming no longer just affect the sea surface," says Valentina Di Miccoli. " Today, we're seeing thermal anomalies reaching the deepest habitats and directly impacting the health of marine ecosystems, including in marine protected areas. The valuable protection and conservation work in these areas alone isn't enough to preserve marine biodiversity; a drastic reduction in greenhouse gas emissions is also needed."
The maximum sea surface temperature anomaly, equal to +3.5 degrees Celsius above the climatological threshold, was recorded in Sardinia between late May and July 2025 in the Marine Protected Area of Asinara Island , during a heat wave that lasted 41 days. The other major anomalies were recorded at Capo Carbonara and Tavolara , with +3.46 degrees above average, at Capo Milazzo (Sicily), with +2.94 degrees, and in the Marine Protected Area of Plemmirio (Sicily), with +2.71 degrees.
The heat accumulated on the sea surface during the summer was also transferred to the depths through the mixing of the water column caused by the wind, causing temperatures to reach 25 degrees at a depth of 30-40 meters and exposing organisms living on the rocky seabed to severe stress.
In 2025, Greenpeace also conducted biological monitoring on Elba Island (Tuscany), the Asinara MPA (Sardinia), and the Torre Guaceto MPA (Puglia). In all three areas, significant impacts were observed , such as necrosis or bleaching of the most vulnerable species, including the yellow gorgonian Eunicella cavolini and the coral Cladocora caespitosa, while the presence of alien species such as Caulerpa cylindracea continues to increase.
(Unioneonline/AD)
