Record-breaking marine heatwave in North Atlantic alarms scientists

There are fears for marine life in the North Atlantic, where surface ocean temperatures between March and May were at their hottest since records began. The unprecedented heatwave has been linked to the developing El Niño system, which causes extreme weather.

Hotter water in the North Atlantic can stress marine species such as fish, coral and seagrass – many of which cannot survive above certain temperatures. © Enric Sala/National Geographic

Sea surface temperatures (SSTs) in the North Atlantic tend to rise in summer, peaking in late August. This year they have risen earlier than usual delivering a category 4 marine heatwave to parts of the North Sea off the coasts of the United Kingdom and Ireland.

The National Oceanic and Atmospheric Administration said that water temperatures in some areas were up to 5 degrees Celsius hotter than usual.

Since 1981, when global satellite observations began, daily SST anomalies in the region have been higher than the previous 42 years since the first week of March 2023.

Added to that are SSTs in the North Atlantic so far for the month of June, which have been about 0.5C higher than the previous warmest temperatures recorded for the month.

Lack of Saharan dust

Scientists say climate change and a lack of Saharan dust are likely contributors to the warmer temperatures. Winds from the Sahara desert that blow clouds of dust, which have a cooling effect on the North Atlantic, are weaker than usual – possibly due to El Niño.

Richard Unsworth, a founding director of Project-Seagrass, told CNN the Atlantic heatwave was “way beyond the worst-case predictions for the changing climate of the region”, adding that it was “truly frightening how fast this ocean basin is changing”.

Hotter water can stress marine species such as fish, coral and seagrass – many of which cannot survive above certain temperatures.

“There’s a very high potential that animals such as oysters, plants and algae will be killed by this European marine heatwave, particularly within shallow waters where temperatures may super heat beyond the background levels,” Unsworth said.

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