Marine heatwaves may have pushed the world’s oceans to a critical tipping point. Scientists fear prolonged ocean warming could become the “new normal.”
In 2023, the Earth experienced unprecedented marine heatwaves across all oceans.
These heatwaves broke records in intensity, geographical extent, and duration, with many lasting more than a year and 96% of the ocean surface being affected.
Following new research, scientists now warn that these prolonged temperature spikes may mark a tipping point for the world’s oceans, with serious consequences for the planet.
Oceans may have undergone a major shift
In 2023, following extreme heatwaves, the North Atlantic and Southwest Pacific Oceans recorded record-breaking surface temperatures.
“We know marine heatwaves have become more frequent and more intense over time due to climate change. We also know that the El Niño phenomenon that began in 2023 allowed heat to penetrate deeper into the ocean,” explained Alex Sen Gupta, climate researcher at the University of New South Wales.
“But these factors alone can’t fully explain the immense scale of the temperature rise that began in 2023.”
Researchers from China, the United States, and Thailand set out to investigate the causes and consequences of this extreme warming. Their findings point to a reduction in cloud cover—allowing more solar radiation to reach the ocean surface—along with weaker winds, which reduced cooling from evaporation, and shifts in ocean currents.
Although the study does not explain why these factors aligned to shatter temperature records, it underlines the urgent need for more research into the mechanisms driving ocean warming.
The study confirms scientists’ fears that the Earth’s oceans have undergone a fundamental shift, entering a new, hotter state that they believe now constitutes the “new normal.”
Zhenzhong Zeng, lead author from the Southern University of Science and Technology, stated that the data suggest ocean heat is accumulating exponentially.
If this is true, it contradicts current climate model projections.
Ocean warming has devastating effects on marine ecosystems and life on Earth
The study also warns of the devastating effects that sustained ocean warming could have on life across the planet.
Oceans play a central role in regulating global temperatures, by absorbing and slowly releasing vast amounts of heat.
Since oceans respond more slowly to changes than the atmosphere, the impacts of marine heatwaves can be both delayed and dramatic, hindering forecasts of short-term extreme weather events like hurricanes and long-term climate shifts.
A prolonged rise in water temperature would also be catastrophic for marine ecosystems, triggering mass extinctions or species migrations.
It also increases the risk of coral reef collapse, which is alarming, particularly because coral loss weakens the oceans’ ability to capture carbon, accelerating global warming.
On land, this would mean faster warming, as warm sea breezes carry hot air inland, potentially leading to droughts, heatwaves, wildfires, and stronger, more widespread storms.
The 2023 Storm Daniel, which killed nearly 6,000 people, is a stark illustration. Attribution studies showed that the storm was 50 times more likely to occur and 50% more intense due to high Mediterranean sea surface temperatures.
Are marine heatwaves the new normal?
These findings are especially concerning given the marine heatwaves of 2024 and 2025, which have boiled oceans across the globe.
This year, Mediterranean Sea surface temperatures reached an all-time high in June.
On June 29, sea surface temperatures hit 26.01°C, according to Copernicus data analyzed by Météo-France. Overall, temperatures were 3 to 4°C above average.
Marine scientists issued new warnings about devastating impacts on biodiversity, fisheries, aquaculture, and weather conditions in Southern Europe and North Africa. In May, a marine heatwave hit the UK, where rising sea surface temperatures are still a relatively new phenomenon.
Parts of the North Sea, English Channel, and Irish coast were up to 4°C warmer than average.
According to scientists, an exceptionally warm and dry spring, combined with weak winds, allowed heat to accumulate on the ocean surface.
They warn that this spike could disrupt marine ecosystems, altering breeding cycles, encouraging harmful algal blooms, or attracting jellyfish, which thrive in warmer waters.
“We must continue to measure, monitor, and model the future of our planet”
A major shift in ocean dynamics that defies current climate models is an alarming prospect.
Some researchers argue that this warning may be premature.
“We don’t know what’s going to happen next year, and it’s possible that [ocean temperatures] will return to a more, let’s say, normal level,” said Neil Holbrook, climatologist at the University of Tasmania, in an interview with New Scientist, adding that current research is based on only a few years of data.
Despite this, scientists support the study’s call to further investigate the drivers of ocean warming.
“While it is urgent to cut our greenhouse gas emissions, it is crucial that we continue to measure, monitor, and model the future of our Earth,” said Jaci Brown, climate lead at Australia’s national science agency CSIRO.
“If we don’t, we won’t be prepared—and we’ll head into the unknown, with devastating consequences for the future of our food, health, and security.”
Source: euronews
