The North Sea was warmer in 2023 than at any time since records began, according to the Helgoland Biological Station of the Alfred Wegener Institute (AWI) in the German port of Bremerhaven.
Measurements show the average water temperature in 2023 was just under 11.9 degrees Celsius, the institute said.
THis was the highest temperature recorded since the Helgoland Reede long-term data series began in 1962. The high temperatures are a consequence of climate change and could have significant consequences for the maritime ecosystem, it said.
The scientists have also recorded further high temperatures in the North Sea this year. The AWI found January, February, March and April 2024 were each among the ten warmest months on average since 1962. "With an average water temperature of 6.9 degrees Celsius, March 2024 was the warmest March since 1962," it said.
The data shows a correlation between the monthly temperatures in the German Bight and the temperatures on the German mainland.
"The North Sea is warming so quickly because it is a shallow sea surrounded by land masses, like a large puddle," said the director of the Helgoland Biological Institute, Prof Karen Wiltshire. "That's why the temperature trends for the mainland are absolutely consistent with those for the water temperature."
The institute warns that marine heatwaves are likely to affect not only surface waters but also seabed habitats.
