Europe’s seas recorded their hottest summer in 45 years, with rising marine heatwaves putting pressure on fisheries and marine ecosystems across the region.

European waters averaged 21.6°C between June and August, according to a Reuters analysis of sea-surface temperature data. The analysis found that temperatures reached record levels in several areas, including the Mediterranean and the English Channel.

An offshore buoy near Mallorca recorded 33.02°C on August 5, the highest temperature recorded within Spain’s port authority buoy network.

Scientists say marine heatwaves are becoming more frequent, intense and widespread as global temperatures rise. The oceans absorb most of the excess heat and retain it longer than land and the atmosphere.

The Bay of Biscay recorded some of the most significant temperature increases this summer. Its waters averaged 21.4°C between June and August, more than 2.4°C above the 1991–2020 average. The area recorded 186 marine heatwave days by the end of August.

The warmer waters have already affected marine life and fishing communities. In northern Spain, researchers estimate that about 95% of large brow