The Mediterranean Sea has just experienced its hottest June on record, with marine heatwaves of "record intensity" affecting 62 percent of its surface, Mercator Ocean International announced Tuesday.
The average surface temperature of this enclosed sea, which is warming faster than the rest of the ocean, reached an average of 23.86°C in June, breaking its previous June record from 2022 (23.72°C), according to Mercator Ocean International, the operator of the European Union’s Copernicus Marine Service.
Almost the entire Mediterranean basin (88 percent) experienced above-average temperatures in June, particularly in its western half, which underwent marine heatwaves "reaching record levels in intensity, duration, and extent," according to a press release.
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Marine heatwaves
As a result, 62 percent of the surface of the Mediterranean Sea was affected by marine heatwaves in June 2025, "the highest extent ever recorded," Mercator explained.
"June was marked by the presence of a heat dome over Europe, which had a significant impact on the Mediterranean Sea with a lack of clouds, no wind, and increased solar radiation," said oceanographer Simon Van Gennip.
Marine heatwaves can fuel hurricanes and cyclones, damage ecosystems, and cause mass die-offs of marine species, he reminded, noting that corals, gorgonians, and bivalves (such as mussels) are the most threatened species in the Mediterranean.
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The first half of 2025 was also the warmest ever recorded in the Mediterranean.
By 12 July, Mercator expects a noticeable decrease in marine heatwaves in the region, thanks to a return of winds that should help better distribute heat into deeper ocean layers.
As for the global ocean, this year recorded its third-warmest June ever, after 2023 and 2024, according to Mercator, with an average surface temperature of 20.75°C.
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One-fifth of the global ocean surface was affected by high-intensity marine heatwaves at the end of June.
Oceans play a climate-regulating role by absorbing 90 percent of the excess heat generated by human activity.
(with AFP)
