Climate Change Drives Record Heat in European Seas, Scientists Warn

Human-caused climate change is the primary driver behind the record-breaking sea temperatures observed around Europe this summer, according to a new analysis by the World Weather Attribution group. The findings, released on Wednesday, highlight severe risks to marine ecosystems and coastal communities.

Last month, the Mediterranean Sea recorded an average temperature of 27°C (81°F), the highest for any July on record. An offshore buoy near Mallorca logged 33°C in early August. The analysis estimates that climate change has added about 2°C of warming to the Mediterranean and roughly 1.4°C to seas off Western Europe.

Claire Bergin, a climate scientist at Maynooth University in Ireland and co-author of the study, said the heat could "completely reshape ecosystems that coastal communities rely on for food and income," and also drive damaging extreme weather on land.

The study found that peak sea temperatures this year in the eastern and western Mediterranean, the Bay of Biscay, and the Iberian coast would have been "virtually impossible" without human-caused climate change. In the Celtic Sea, the most extreme temperatures would have been expected only about once a century in a world without global warming.

Hotter seas raise humidity and overnight temperatures in coastal areas, and can fuel intense storms later in the year. The planet's average temperature has risen to about 1.4°C above pre-industrial levels, largely due to greenhouse gas emissions from burning fossil fuels, according to the World Meteorological Organization. This hotter baseline allows heatwave-driving high-pressure systems to reach higher temperatures.

Sea temperature spikes can cause mass die-offs of species such as corals and disrupt food supplies for birds and mammals, with cascading effects through food chains. John Bruno, a marine ecologist at the University of North Carolina, noted that some species are moving north to cooler waters, but not all can adapt. "We are rapidly approaching the absolute biological limits of adaptation for many species," he said.

The analysis also revealed that about 90% of the Bay of Biscay and 80% of the western Mediterranean have experienced marine heatwave conditions this year. Without global warming, that figure would have been closer to 40%.