Climate change

New study: Ocean surface temperatures warming four times faster than in 1980s

A new study, published today, argues that the rate of ocean warming has more than quadrupled over the past four decades. 

28/01/2025
Words by Nane Steinhoff
Photograph by Thomas Horig

A new study, published in the journal Environmental Research Letters on 28 January, found that, on average, today’s ocean surface temperatures warm four times faster than in 1980s. While ocean temperatures were rising at about 0.06 degrees Celsius per decade in the late 1980s, they are now increasing at 0.27 degrees Celsius per decade.

The findings help explain why 2023 and early 2024 saw unprecedented ocean temperatures.

In the study, the researchers argue that the accelerating ocean warming rate is driven by the Earth’s growing energy imbalance due to more of the sun’s energy being absorbed into the Earth system than is escaping back into space.

Since 2010, this energy imbalance has doubled, according to the study, due to increasing greenhouse gas concentrations and because Earth is reflecting less sunlight to space than before.

Professor Chris Merchant, lead author at the University of Reading and National Centre for Earth Observation, said: “If the oceans were a bathtub of water, then in the 1980s, the hot tap was running slowly, warming up the water by just a fraction of a degree each decade.

“But now the hot tap is running much faster, and the warming has picked up speed. The way to slow down that warming is to start closing off the hot tap, by cutting global carbon emissions and moving towards net-zero.” 

In 2023 and early 2024, global ocean temperatures hit record highs for 450 days straight.

While some of the warming was attributed to the natural warming event of El Niño in the Pacific, the rest of the record warmth, according to the researchers who compared the events to a similar El Niño event in 2015-16, was explained by the sea surface warming up faster in the past ten years than in earlier decades. According to them, 44% of the record warmth was attributable to the oceans absorbing heat at an accelerating rate.

As rising ocean temperatures impact everything from coral reefs to fisheries and livelihoods, the new findings matter for the climate as a whole, suggest that longer-term impacts could include higher sea levels, as well as more frequent and more extreme storms, and highlight the urgent need to reduce fossil fuels.

Click here for more from the Oceanographic Newsroom.

Words by Nane Steinhoff
Photograph by Thomas Horig

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