The seas in Greece hit their warmest level in 40 years in the summer of 2024, a report by Greek researchers at the universities of Thessaloniki, Aegean, and Thrace has found.
The researchers studied temperature reports for the Greek seas from satellites as of 1982 before concluding that the entire Aegean, Ionian, and Cretan Seas registered the highest temperatures in the summer months of 2024 than any other year in the last 40 years.
Speaking to athens news agency amna.gr, researcher Vassilis Kolovoyannis, one of signatories of the report who works from the University of the Aegean’s Department of Oceanography and Marine Biosciences, said that the areas most affected by high temperatures were the Northeast and Southeast Aegean, the South Cretan Sea, and the Ionian Sea.
What concerned the researchers was that the rise in temperatures was not superficial but extended as far down as 50 meters. “This means there is a cumulative phenomenon at work,” Kolovogiannis explained, adding that the researchers also observed “changes in the usual mechanics of cooling in the Aegean, such as the inflow of cold waters from the Black Sea, which was low, and the coastal rise of colder masses.” One of the research’s key findings was also the duration of high marine heatwaves that appeared this summer (2024), especially in the North Aegean, which lasted to August.
Threat to acquaculture
Commenting on the numbers, co-signatory of the report Yannis Androulidakis, associate professor at the same department who also collaborates as researcher with the Aristotle University of Thessaloniki’s Civil Engineering School, what research shows is that the Greek seas’ temperatures are rising every summer, to the rate of over 0.5 degrees per decade. In some regions, sea temperature rose to 30C this summer, he said, with a faster rate of increase in the North Aegean (particularly Thessaloniki’s Thermaic Gulf), smaller areas of the Ionian Sea, and regions of the Dodecanese.
This outlook is “the worst for the ecosystem” when it combines high temperatures with long duration. For example, he said, the production of mussels in coastal aquaculture farms in the greater region of Halastra, west of Thessaloniki, with dire financial repercussions in 2024 and possible after-effects for next year as well, as the offspring die off from the warmth, he told ANA-MPA.
Both professors spoke of repercussions such as changes in the oxygen in the seas that also lead to the invasion of heat-friendly species in the South Aegean and the Cretan Sea. Storm phenomena such as Ianos will gain strength when they move over the sea and temperatures are higher, creating systems like the tropical storms.
Androulidakis added that what would help their researchers more is to increase the monitoring stations, because there is only one in operation for open seas, off northern Crete at the Cretan Sea, he said. Such a network would allow better data instead of sporadic measurements by missions to specific areas, he noted.
The scientists signing the report, besides the two mentioned so far, include Christos Makris and Yannis Krestenitis. The entire report (“Evidence of 2024 Summer as the Warmest During the Last Four Decades in the Aegean, Ionian, and Cretan Seas”) is available in English HERE.
