News Release

Extreme Marine Heatwave


Sea surface temperatures for June are the highest seen in nearly two centuries, and waters around the U.K. and Ireland have been classified as experiencing a category 4 marine heatwave. Sea temperatures in the region are up to 4℃ above normal for this time of year. On June 17, average surface temperatures peaked at 23℃ (73.4℉). 

COLIN MCCARTHY;, @US_Stormwatch 
    McCarthy is the founder of US_Stormwatch, where he researches and analyzes weather patterns and events. He launched the account in 2017, at age 13. 

McCarthy told the Institute for Public Accuracy: “The atmosphere has been incredibly warm around the U.K. over the last month. This June will be the hottest in recorded history in the U.K. since records began in 1884. 

“Climate change is making record hot events more intense as well as more frequent. The intensifying El Niño in the Pacific––as well as less Saharan dust over the North Atlantic, which generally helps shield more sunlight from heating ocean surface––are also likely playing a contributing role” in the heatwave.

“Marine heatwaves (MHWs) are different than those [that occur] on land,” McCarthy said. “While heatwaves on land typically last less than a week, marine heatwaves can last weeks, and even months.” They can also lead to “devastating impacts” on marine habitats: coral bleaching, marine ecosystem disruption, and mass animal die-offs. MHWs also threaten biodiversity and make extreme weather more likely, according to the International Union for Conservation of Nature. 

It will take time, McCarthy said, for researchers to analyze the effects of this particular marine heatwave. Already, however, “algae blooms have been reported in the North Sea.” Harmful algal blooms can reduce the ability of aquatic life to find food, precipitate marine wildlife migrations, and potentially poison wildlife