The world’s oceans reached the highest temperatures ever recorded this weekend and are likely to warm even more in the coming months, posing a threat to life both in water and on land, the European climate service Copernicus reported on Monday.
Driven by a natural phenomenon of El Niño that continues to intensify, but has already reached gigantic proportions, and due to human-caused climate change, global ocean temperatures reached 70 degrees Fahrenheit (21.1 degrees Celsius) on Friday and Saturday, narrowly surpassing the average daily record set in March 2024, said Samantha Burgess, strategic climate manager at Copernicus.
“This is one more sign that our climate system is under stress and that the ocean is under immense pressure,” Burgess said.
Jane Lubchenco, oceanographer and former director of the United States National Oceanic and Atmospheric Administration (NOAA), called this record “very worrying.”
“Such a warm ocean destabilizes weather patterns and endangers food security, economic prosperity, and marine life,” Lubchenco wrote in an email. “A warmer ocean is not our friend.”
Warmer waters lead to stronger storms and hotter nights
According to Burgess, when the ocean warms, it becomes more acidic and contains less oxygen, which hurts food industries that depend on the sea. Additionally, it alters ocean currents and weather patterns, which increases the intensity of storms, causing them to dump more rain and make storm surges stronger, he added.
“When the ocean is warmer, as has happened in Europe this summer, the impact of heat waves intensifies because the cooler nighttime temperatures are not reached thanks to the sea breeze that comes from the ocean when it is very hot,” he noted.
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Normally, since most of the southern hemisphere is covered by ocean, global sea surface temperatures peak in March and April, when the southern summer comes to an end. But this year the record was set in August, according to Burgess.
Thus, the oceans will continue to warm until the current El Niño phenomenon – a natural and temporary warming of some areas of the Pacific that subsequently alters the climate and raises global temperatures – reaches its peak, which is expected to occur sometime between November and January, he said.
El Niño already has the same magnitude as the recent phenomena and continues to intensify; At its peak, it is expected to reach unprecedented levels. It is responsible for much of the heat in the oceans, and long-term warming caused by the burning of coal, oil and gas has raised water temperatures by 1.4°F (0.8°C), Burgess said.
“What breaks my heart is that this starts so early and is so atypical that you know that when it reaches its peak, it will be unprecedented,” said Boris Worm, a professor of biology at Dalhousie University in Canada. “It’s not normal for the ocean to do this.”
“The thing is that normal no longer exists,” he added.
Hot water kills corals and anchovies
“It’s scary,” said John Bruno, a marine ecologist at the University of North Carolina. “It’s not even October. Typically the Caribbean peaks in late September or early October. And I think next year, in the Southern Ocean, in the Great Barrier Reef… yeah, I’m very worried about what’s going to happen in the southern hemisphere in February and March.”
The amount of heat-sensitive coral still alive today is about one-fifth of 1990s levels, Bruno said. However, recently scientists have discovered that some species of coral — especially the “herbaceous” type, not the iconic and long-lived ones like the staghorn coral — are adapting to warmer water and the mass extinction that was feared is not occurring, he explained.
Bruno and Worm warned of collapsing fisheries and food shortages.
Both mentioned the largest fishery in the world, that of the Peruvian anchovy. It usually collapses during El Niño and the phenomenon is especially likely in this heat, Worm said. This disrupts the food chain as larger fish, marine mammals and seabirds feed on them.
Worm explained that when the water warms, larger creatures can swim to colder waters, halfway across the ocean, but “the anchovies can’t leave, so they just don’t reproduce or they starve.” And this affects seabirds and even the humans who depend on them.
With warmer waters, “it doesn’t affect everyone equally, obviously, but the whole system collapses,” Worm said. “It’s like when an economy is destabilized. It’s like everything falls apart. Some sectors may do a little better, but, in general, everyone loses.”
Burgess said that as waters warm off the coast of Europe, people are seeing more jellyfish, and Bruno said the same thing could be happening on the east coast of the United States.
“Jellyfish tend to be opportunistic and like warm waters,” Worm said. “So yeah, I would expect them to do a little bit better.”
Another former NOAA director, Rick Spinrad, stated that the ocean is the planet’s thermostat, so “as long as we depend on a healthy ocean for our safety, prosperity and well-being, these record sea surface temperatures portend even greater challenges for all of us.”
This story was translated from English to Spanish with an artificial intelligence tool and was reviewed by an editor before publication.