Record temperatures were recorded this summer in the Greek seas, making it the warmest in forty years according to a study by researchers from three universities in the country, namely the Aristotle University of Thessalonikiof University of the Aegean and his Democritus University of Thrace. The researchers, studying data from satellite observations from 1982 onwards, found that during the summer of 2024, the warmest conditions in the last forty years occurred across the entire Aegean, Ionian and Cretan Seas.

As the researcher of the Department of Oceanography and Marine Biosciences of the University of the Aegean explains to the Athenian-Macedonian News Agency, Vassilis Kolovogiannis and one of the authors of the study, among the regions most affected are the North-East and South-East Aegean, the South Cretan Sea and the Ionian Sea and emphasizes that what is worrying and worries scientists is that the increase in temperature is not only superficial but extends deep.

“This increase in temperature extends in depth, which means that there is an accumulative effect,” says Mr. Kolovogiannis to APE-MPE. In particular, according to the research, high temperatures extended to depths of 50 meters in some areas, indicating a deep and widespread warming of the upper regions. At the same time, changes were observed in the usual cooling mechanisms of the Aegean, such as the inflow of cold waters from the Black Sea, which was reduced, and the coastal emergence of colder masses.

At the same time, one of the most important findings of the study is the duration of the intensity of the sea heat waves that appeared this summer.

Specifically, as noted in the research, intense and long-lasting sea heatwaves were recorded in the Northern Aegean until August 2024.

As the associate professor at the Department of Oceanography and Marine Life Sciences of the University of the Aegean, a collaborating researcher at the School of Civil Engineering of the AUTH and one of the authors of the research, emphasizes to APE-MBE, Yannis Androulidakiswhat is recorded both by this study and by others is a continuous increase in the temperature of the Greek seas in the summers. This increase, as he explains, exceeds 0.5 degrees per decade while adding that this summer the temperature reached up to 30 degrees Celsius in some areas. “The increasing trend is more intense in the North Aegean, in smaller areas of the Ionian and in areas of the Dodecanese. But mainly North Aegean and Thermaikos show the highest trends”, underlines Mr. Androulidakis. At the same time, as he notes, just as important beyond the intensity of temperatures was the long-lasting sea heat wave. “This is the worst thing for the ecosystem, i.e. the long duration of some events combined with their intensity,” he emphasizes.

On his part, Mr. Kolovogiannis points out that although the episodes of sea heat waves were not the most that have existed “what was more intense was their intensity, i.e. the high temperatures and their duration”.

Examining the effects of the continuous increase in the temperature of the seas, Mr. Androulidakis cites as an example the Thermaic Gulf and the mussel production which due to the thermal shock was destroyed in the coastal aquacultures of the Chalastra region, causing very serious economic losses for 2024, but also possible significant reductions in production capacity for the following year.

“A problem has arisen not only in this year’s production but also in future production because there is also mortality in the newborns”, the professor points out to APE-MPE and adds that the rise in temperature also creates changes in the oxygen of the sea, which in turn it causes various other disasters in biological agents. On his part, Mr. Kolovoyiannis explains that one of the effects of the continuous increase in temperature is the invasion of thermophilic alien species in principle in the South Aegean and the Cretan Sea.

Furthermore, as the researchers emphasize, the connection and correlation of the increase in the temperature of the seas with strong meteorological phenomena such as e.g. Janus. “These extreme weather events gain energy as they move over the sea. So, think that when we have warmer seas, these kinds of systems that are more and more intense in the Mediterranean – sort of like tropical systems even though we don’t have a tropical climate – they’re fed, they get energy, they’re fed by warm water. The more often we have more intense, warm waters, greater sea heat waves, phenomena associated with floods, they tend to become more intense”, notes Mr. Androulidakis.

At the same time, due to the continuous rise in the temperature of the Greek seas, the need to monitor them becomes more and more imperative, something which, as pointed out by Mr. Androulidakis, is missing as the measuring stations are very few. “The open sea monitoring network was the Neptune measuring stations of the Hellenic Center for Marine Research. At the moment, only one is operating – in North Crete, in the Cretan Sea”, he emphasizes and adds that a sufficient network is needed so that there is a continuous recording. “This could help us in so many areas. There are only sporadic measurements from missions, which can be done, from some measurements in specific areas”, he underlines.

It is noted that the research is co-signed by Yiannis Androulidakis, Vassilis Kolovogiannis, Christos Makris, Yiannis Krestenitis.

The study resulted from the collaboration of researchers from the Department of Oceanography and Marine Life Sciences (University of the Aegean), the Department of Civil Engineering (APTH) and the Department of Civil Engineering (DPTH).