Italian Seas Warming to 40 Meters Depth, Greenpeace Warns

Marine heatwaves in Italian seas have transitioned from isolated incidents to a persistent issue, impacting ecosystems as deep as 40 meters, warns Greenpeace Italia's annual 'Mare Caldo' (Hot Sea) project report. The study highlights that these thermal anomalies and heatwaves are now a constant feature of the marine environment.

Collaborating with the University of Genoa and the National Institute of Oceanography and Experimental Geophysics (OGS), the research found that rising water temperatures affect Italian coastlines regardless of their location or environmental protection status. Scientific data collected from fourteen monitoring stations in 2025 indicated that marine heatwaves in several Mediterranean zones surpassed 200 days in duration. Surface temperatures during these periods were 1.5 to 2.5 degrees Celsius above the climatological average.

The consequences are particularly severe for species crucial to rocky seafloor structures. The report documented mortality rates of 30% to 60% in colonies of the yellow gorgonian (Eunicella cavolini) off the island of Elba in Tuscany. Significant damage was also observed in the Asinara Island reserve in Sardinia, with the coral species Cladocora caespitosa showing severe deterioration in various protected areas.

Alongside the decline of native species, scientists have noted an increase in organisms that thrive in warmer waters and the expansion of invasive species, such as the alga Caulerpa cylindracea. The Mediterranean barracuda, a thermophilic fish, is also advancing into new areas. Environmental DNA (eDNA) analysis in the Torre Guaceto and Asinara reserves revealed the presence of several exotic algae not visible to the naked eye.

Greenpeace emphasized that while Marine Protected Areas are vital for enhancing coastal ecosystem resilience, they are insufficient on their own. The organization urgently calls for a drastic reduction in global greenhouse gas emissions to combat the escalating marine warming crisis.