Marine heatwaves may have pushed the planet’s oceans to a critical tipping point. Scientists fear that prolonged ocean warming could become the “new normal.”
In 2023, the Earth experienced unprecedented marine heatwaves across its oceans.
These heatwaves set new records in terms of intensity, geographic extent, and duration—many lasting more than a year, affecting 96% of the ocean’s surface.
Following new research, scientists now warn that these prolonged temperature spikes could signal a tipping point for the world’s oceans, with severe consequences for the planet.
Oceans may have undergone a fundamental change
In 2023, following heatwaves, the North Atlantic and Southwest Pacific oceans reached record surface temperatures.
“We know marine heatwaves have become increasingly frequent and intense over time due to climate change. We also know that the El Niño event that began in 2023 allowed heat to penetrate deeper into the ocean,” explains Alex Sen Gupta, climate researcher at the University of New South Wales.
“But these factors alone cannot explain the immense scale of the rise that began in 2023.”
Scientists from China, the U.S., and Thailand studied the causes of this extreme warming and its current and future impacts.
Their research revealed that reduced cloud cover was a key factor, allowing more solar radiation to reach the water, along with weakened winds that reduce cooling by evaporation, and changes in ocean currents.
While the study does not explain why these factors coincided to shatter temperature records, it highlights the urgent need for further research into the mechanisms driving ocean warming.
The study confirms scientists’ fears that Earth’s oceans have undergone a fundamental change, shifting to a warmer new state now considered the “new normal.”
Zhenzhong Zeng, lead author from the Southern University of Science and Technology, stated that the data indicate ocean heat is accumulating exponentially.
If true, this trend contradicts current climate model projections.
Ocean warming has devastating effects on marine ecosystems and life on land
The study also warns about the devastating effects that permanent ocean warming could have on life on Earth.
Oceans play a central role in regulating global temperatures by storing and slowly releasing vast amounts of heat.
Because oceans respond more slowly to changes than the atmosphere, the effects of heatwaves can be both delayed and dramatic, complicating predictions of short-term extreme weather events like hurricanes, and long-term climate changes.
A prolonged increase in water temperature would be catastrophic for marine ecosystems, causing massive extinctions or species migrations.
It also raises the risk of coral reef collapse, which is concerning because coral loss reduces the ocean’s ability to sequester carbon, further accelerating warming.
On land, this would mean accelerated warming as sea breezes carry hot air inland, potentially causing droughts, heatwaves, wildfires, and more intense and widespread storms.
The 2023 storm Daniel, which caused nearly 6,000 deaths, was a stark example. Attribution studies revealed that the storm was 50 times more likely to occur and 50% more intense due to the high sea surface temperatures in the Mediterranean.
Are marine heatwaves becoming the new norm?
These findings are especially alarming given the marine heatwaves of 2024 and 2025, which have boiled the world’s oceans.
This year, Mediterranean sea surface temperatures reached their highest June levels on record.
On June 29, sea surface temperatures hit 26.01°C, according to data from Copernicus analyzed by Météo-France. Overall, temperatures were 3 to 4°C above average.
Marine scientists issued new warnings about the devastating impacts on biodiversity, fisheries, aquaculture, and weather conditions in southern Europe and North Africa.
In May, a marine heatwave struck the UK—a country where sea surface temperature rises remain a relatively new phenomenon.
Parts of the North Sea, the English Channel, and the Irish coast were up to 4°C warmer than average.
Scientists say an unusually warm and dry spring, combined with weak winds, allowed heat to accumulate at the water’s surface.
They warn this surge could disrupt marine ecosystems by altering breeding cycles, encouraging harmful algal blooms, or attracting jellyfish that thrive in warmer waters.
“It is essential that we continue to measure, monitor, and model the future of our Earth”
A fundamental shift in ocean dynamics defying current climate models is an alarming prospect.
Some researchers believe the warning may be premature.
“We don’t know what will happen next year, and ocean temperatures might return to a more ‘normal’ level,” said Neil Holbrook, climatologist at the University of Tasmania, Australia, to New Scientist magazine, noting that current research relies on only a few years of data.
Despite this, scientists support the article’s call to study the drivers of ocean warming.
“While urgent action to reduce greenhouse gas emissions is necessary, it is essential that we continue to measure, monitor, and model the future of our Earth,” said Jaci Brown, climate lead at Australia’s CSIRO.
“If we don’t, we won’t be prepared and will face an unknown future with disastrous consequences for our food, health, and safety.”
