Climate change: 70 percent of Mediterranean under heat wave

According to a rapid citation analysis published by the World Weather Attribution (WWA) network recently, the sea temperatures measured in European seas during the summer of 2026 would have been "almost impossible" to reach in the Mediterranean if there had been no human-induced climate change. WWA scientific report number 90, authored by Claire Bergin and her team, examined the 14-day periods with the warmest sea surface temperatures of the year and July in four different regions.

The most direct results for Turkey emerge in the basin that the study defines as the "Eastern Mediterranean." WWA includes the Adriatic, Ionian, and Aegean Seas in this definition, indicating that the Turkish coast is directly included in the analysis. According to the report, the percentage of areas experiencing maritime heatwave conditions in the region approached 70% in 2026. In a climate 1.4 degrees colder, without human-induced warming, this rate would have remained at 9%. The World Wildlife Service (WWA) estimates that an approximate 2-degree Celsius temperature increase in Mediterranean basins can be directly attributed to human-induced climate change.

The WWA defines a maritime heatwave as sea surface temperature exceeding the local 90th percentile threshold for at least five days, compared to the 1982-2011 climatology. Warming rates attributable to climate change in other regions were lower: 1.4 degrees Celsius in the Bay of Biscay–Iberian Peninsula region; and 1.3 degrees Celsius in the Celtic region, encompassing Ireland and western Britain. The percentage of areas experiencing heatwaves was calculated as 80% in the Celtic region (compared to 30% in a colder climate scenario), 90% in the Iberian-Biscay region (40%), and 80% in the Western Mediterranean (40%).

The methodology section of the report notes that the warming trend observed in three basins outside the Celtic region is significantly stronger than predicted by climate models. WWA therefore describes its 2-degree estimate for the Mediterranean as a "conservative estimate." According to Catherine Gregory, a researcher at the University of Bern and a co-author of the report, the average temperature across the entire Mediterranean in July was slightly over 27 degrees, marking the highest July temperature on record. A buoy west of Mallorca recorded temperatures above 33 degrees in open water.

Copernicus: Hottest July on Record in Non-Polar Oceans

The analysis follows the Copernicus Climate Change Service's announcement that July 2026 will be the hottest July on record in oceans between 60° South and 60° North latitude. According to the service, average sea surface temperatures in this region rose to 20.96 degrees; record July temperatures were recorded in the Atlantic around Europe and the Western Mediterranean. Copernicus attributes part of this temperature increase to developing El Niño conditions in the equatorial Pacific.

According to data from the Copernicus Marine Service, the largest temperature deviations were recorded in the Western Mediterranean on August 13, 2026. In particular, temperatures in the Bay of Lions in southern France rose approximately 6 degrees above average. The same data shows below-average water temperatures in some parts of the Aegean Sea; this reveals that the picture is not uniform even within the region.

The WWA report states that extreme sea temperatures are leading to mass deaths in habitat-forming species such as corals, sponges, and macroalgae; this effect is reflected in invertebrates, fish, seabirds, and marine mammals along the food chain. Species tied to the seabed are more vulnerable because their capacity for displacement is limited. Speaking to Reuters, John Bruno, a marine ecologist from the University of North Carolina, emphasized that some species are shifting northward to colder waters, but not all are adapting, saying: "For many species, we are rapidly approaching the absolute biological limits of adaptation." The report also recalls that the European Centre for Disease Prevention and Control (ECDC) has drawn attention to the increased risk of waterborne diseases such as vibriosis.

Data from various institutions also confirm this warming trend. According to the Copernicus Marine Service's Ocean State Report, the Mediterranean Sea is warming faster than the global average since satellite records began in the 1980s. The European Environment Agency also reports that all European seas have warmed significantly since 1870, particularly since the late 1970s; a high-emissions scenario predicts an additional increase of 2 to 6 degrees by 2100. According to WWA calculations, if global warming reaches 2.8 degrees compared to the pre-industrial era, similar extreme events seen in 2026 will be 1.3 to 1.9 degrees warmer.