Unusually warm sea: "This affects all of Scandinavia. It's extreme"

 

Unusually warm sea: "This affects all of Scandinavia. It's extreme"

 

Sea surface temperatures in vast areas off Norway's coast are at least 5 degrees above normal, according to the Norwegian Meteorological Institute. Marine researchers are concerned.

 

Per Helge Berg / NTB

Norwegian News Agency

Published 30 July 2025 - 00:01

https://www.sciencenorway.no/climate-climate-change-global-warming/unusually-warm-sea-this-affects-all-of-scandinavia-its-extreme/2536244

 

"We're seeing temperatures of 22 to 23 degrees in the sea. That's far too high. I can't recall ever seeing such extreme deviations," state meteorologist Leonidas Tsopouridis tells the Norwegian Broadcasting Corporation NRK.

 

The unusually warm sea extends from the coast of Trøndelag to Sweden and Denmark.

 

"This affects all of Scandinavia. It's extreme," says the meteorologist. He points out that this could cause stress and increased mortality among fish and other marine life.

 

The Institute of Marine Research has also recorded unusually high surface temperatures in the sea off the coast of Norway.

 

"We've recorded 22 degrees at our monitoring station in the Skagerrak," says oceanographer Jon Albretsen.

 

That figure represents the average temperature from June until July 26.

 

"The highest single measurement was taken on July 24. It was 23.8 degrees, which is on par with the previous record set in 2008," he says.

 

By comparison, the typical sea surface temperature for this time of year is around 16 degrees.

 

Continuing last year's trend

Earlier this year, the Institute of Marine Research reported that the marine heatwave that hit the Norwegian coast last summer is clear evidence that climate change is impacting marine ecosystems.

 

Researchers believe there is still limited understanding of how such changes affect different species, and how activities like aquaculture may intensify the effects.

 

'A lack of knowledge creates uncertainty and leaves room for surprises,' the researchers wrote in the report, which warns of unforeseen consequences.

 

Impacts on aquaculture and CO2

Last year's marine heatwave had major consequences for fish farming companies, as warmer waters caused a surge in salmon lice outbreaks in Northern Norway.

 

The ocean is also one of the planet's largest carbon sinks. On average, it has absorbed 10.5 billion tonnes of CO₂ each year over the past decade. This accounts for 26 per cent of total CO₂ emissions.

 

The ocean's ability to absorb carbon weakens as sea temperatures rise. This can make the water more acidic and reduce its calcium levels.

 

The effects of ocean acidification on marine ecosystems could be serious. Additionally, warmer water leads to more ice melting and less ice in the northern regions.