"The maximum sea surface temperature record was broken in the Mediterranean Sea yesterday... with a daily median of 28.90C," Spain's leading institute of marine sciences said.

The previous record occurred on July 24, 2023, with a median value of 28.71C, said Justino Martinez, researcher at the Institut de Ciencies del Mar in Barcelona and the Catalan Institute of Research for the Governance of the Sea.

"The maximum temperature on August 15 was attained on the Egyptian coast at El-Arish (31.96C)," but this value is preliminary until further human checks can be carried out, he added.

The preliminary readings for 2024 come from satellite data from the European Copernicus Observatory, with records dating back to 1982.

It means that for two successive summers the Mediterranean will have been warmer than during the exceptional summer heatwave of 2003, when a daily median was measured at 28.25C on August 23, a record that had stood for twenty years.

"What is remarkable is not so much to reach a maximum on a given day, but to observe a long period of high temperatures, even without breaking a record," Martinez told AFP earlier this week.

"Since 2022, surface temperatures have been abnormally high for long periods, even in a climate-change environment," he said.

The Mediterranean region has long been classified as a hotspot of climate change.

Oceans have absorbed 90 percent of the excess heat produced by human activity since the dawn of the industrial age, according to scientists.

This excess heat continues to accumulate as greenhouse gases, mainly from burning oil, gas and coal.

The overheating of the oceans is predicted to impact marine plant and animal life, including on the migration of certain species and the spread of invasive species.

This could threaten fish stocks and thus undermine food security in certain parts of the globe.

Warmer oceans are also less capable of absorbing carbon dioxide (CO2), reinforcing the vicious cycle of global warming.