Marine heat waves in the Mediterranean may have severe consequences on the inland sea, as fauna and flora alike struggle with high temperatures.

From Spain to Turkey, the Mediterranean Sea has seen a series of exceptional temperatures this summer, with peaks raging from 3 to 5 degrees Celsius (5.4-9 Fahrenheit) above the norm for this time of year. Water temperatures along the coastlines have been found in excess of 30 C (86 F) for multiple days in a row. In the hottest area, around Israel, Cyprus, Lebanon, and Syria, the average summer sea temperature is now over 31 C (88 F), the temperature of a comfortable swimming pool.

The heat waves rolling over Europe, the Middle East, and North Africa have made plenty of headlines, with death tolls and wildfires making for big news. But while many have taken to the sea for relief from the heat, the rising sea temperature is still easy to miss.

Marine heat waves happen just like atmospheric heat waves. Air or water currents build up areas of warmth, and local conditions prevent it from dissipating. Both have gotten much more extreme in recent years, due to human-induced climate change.

“We are pushing the system too far. We have to take action on the climate issues as soon as possible,” says Joaquim Garrabou, a researcher for the Institute of Marine Sciences in Barcelona, Spain. His team recently published a report on marine heat waves in the Mediterranean Sea between 2015 and 2019. Their report detailed huge mortality rates in 50 species of coral, sponges, and algae along the coastlines. Sea life down to a depth of over 150 feet was affected.

The report predicts that this imminent biodiversity loss is already well underway, and will inevitably proceed farther west with each successive heat wave.

The report has been given directly to policymakers in the area, to help underscore the importance of pro-climate legislation.

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