Sea temperatures in the Dubrovnik area are approaching last year's record, and Dr. Natalija Dunić from the Institute of Oceanography and Fisheries details the chain reaction of global warming-from invasive species to seawater intrusion into the Neretva River.
According to data from the State Hydrometeorological Institute, the sea temperature in Dubrovnik reached 29.1 degrees Celsius on Monday, close to last year's record of 29.7 degrees. An even more extreme reading was taken at Malo Jezero on the island of Mljet, where the sea warmed to a staggering 30.7 degrees Celsius.
These figures confirm the continuation of a worrying trend of Adriatic Sea warming, the consequences of which scientists are already recording along the entire Croatian coast and inland.
Dr. Natalija Dunić, a scientist from the Laboratory for Sea Physics at the Institute of Oceanography and Fisheries (IZOR) in Split, points to dramatic changes in the marine ecosystem. "The rise in sea temperature affects marine life, so today we have foreign species, including some invasive ones, that have stayed here," warns Dunić.
Tropical species that previously arrived in the Adriatic via ballast water or on their own could not survive the winter. Now conditions are so favorable that in Istria, for example, comb jellies are successfully reproducing and surviving the cold period. Alongside them, divers in the Dubrovnik area are increasingly encountering pufferfish and lionfish.
"The consequences of global warming this year are frightening. Look at the low river levels these days," Dunić points out, linking marine and terrestrial phenomena.
Public attention has also been drawn to the occurrence of meteotsunamis in the Adriatic. Unlike classic tsunamis caused by earthquakes or landslides, meteotsunamis are linked to sudden atmospheric changes. "When we talk about a meteotsunami, conditions need to align, and unlike hurricanes, they are extremely difficult to forecast," explains Dunić. When pressure oscillations, storm direction, and a specific bay shape-such as those in Vela Luka or Mali Lošinj-coincide, pronounced waves can occur.
Severe summer storms, like those recorded in July, are a direct consequence of global warming. Dunić describes the mechanism: "You have an intrusion of Arctic air at minus five, six, or minus 15 degrees, at three, four, or five thousand meters altitude, while at the surface it's 38 degrees Celsius. Huge differences in temperature and pressure at ground level and at altitude accelerate vertical currents, leading to stronger wind shear."
The independent network of scientists MedECC, dedicated to climate change in the Mediterranean basin, has produced a special report with alarming predictions. According to their analyses, by 2040 the average temperature will be 2.2 degrees Celsius above pre-industrial levels. For every degree of warming, precipitation will decrease by four percent.
"The rise in sea level in the Mediterranean is most influenced by the melting of European ice caps and rising temperatures. Looking at global seas, the Mediterranean is what scientists call a 'hot spot' when it comes to temperature rise," notes Dunić. By 2100, sea levels could rise by more than 90 centimeters, and as much as 40 percent of endemic fish species could disappear.
The document "Preparedness and Risk Management Plan for the World Heritage Site of the Old City of Dubrovnik" reveals that the annual sea-level rise in Dubrovnik has accelerated from 0.83 millimeters to 3.62 millimeters per year. The authors warn of an increasing risk of flooding and erosion, including the possibility of seawater intrusion into the Old City's sewage system.
Salinization of water and soil is already causing loss of agricultural land. IZOR's Laboratory for Sea Physics conducted research on the Neretva River that confirmed a negative impact on biodiversity and agricultural production. "In field research from the Neretva estuary to Metković, we found seawater intrusion all the way to the town of Metković itself. It doesn't happen year-round, but seasonally and depending on conditions, because it won't occur when it rains, but there's no doubt that in summer and autumn, seawater reaches all the way to Metković," concludes Dunić.
