Pacific Ocean temperatures are rising fast, raising fears that a powerful El Nino pattern could bring record global heat and chaotic weather, and fresh damage to coral reefs already weakened by climate change.
Issued on: 25/05/2026 - RFI
Fish swim over bleached coral near Koh Tao island in southern Thailand in June 2024. Scientists warn a powerful El Nino in 2026 could cause further damage to coral reefs already weakened by repeated bleaching. © AFP - LILLIAN SUWANRUMPHA
El Nino is a natural climate pattern that develops in the Pacific every two to seven years and can disrupt weather around the world, bringing drought to some regions and heavy rain to others.
Forecasters at the US National Oceanic and Atmospheric Administration (NOAA) say there is about an 80 percent chance of El Nino developing by July.
Sea temperatures in key parts of the equatorial Pacific are climbing quickly, while a large pool of unusually warm water is building beneath the surface.
Several weather services predict Pacific temperatures could rise by 2.5C or more above average later this year. Only three El Nino events since 1877-78 have crossed the 2C mark, in 1982-83, 1997-98 and 2015-16.
“There’s definitely something coming. We’re very confident about that, and it looks like it will be a big event,” Adam Scaife, head of long-range prediction at the UK Met Office, told French news agency AFP.
Unpredictable winds
The NOAA says there is a one in three chance this episode will reach 2C or above, putting it in “super El Nino” territory. But scientists say its final strength will depend on winds that remain difficult to predict.
The strongest El Ninos usually form when trade winds weaken across the Pacific, allowing more warm water to spread across the ocean surface. But those winds can also strengthen unexpectedly.
“When that happens, it pauses the growth of El Nino or even reverses it,” said Michelle L’Heureux, NOAA’s El Nino-Southern Oscillation lead.
“Ultimately the strength of this event will be likely influenced by these details, like the low-level winds, which we cannot predict many months in advance.”
New record possible
El Nino tends to peak around December, but ocean heat is released slowly and can push global temperatures higher in the years that follow.
Many record-temperature years, including 1998, 2010, 2016, 2023 and 2024, came during or after major El Nino events.
There “could easily be a new record level of global warmth in 2027” if an extreme El Nino takes shape this year, Scaife said.
Even a weaker El Nino would be occurring in a world already warmed by climate change.
“The impacts of this El Nino – on things like rainfall and of course temperature – are riding on top of climate change, and could well be larger than anything we’ve seen in the past,” Scaife added.
Scientists also stress that stronger El Ninos raise the odds of more severe impact, but do not guarantee them.
Reefs under pressure
Researchers are also warning of a heavy toll on coral reefs, which have already suffered repeated bleaching as oceans warm.
“Every global coral bleaching event has been during an El Nino year,” explained Clint Oakley, a coral scientist at Victoria University of Wellington.
A strong El Nino could prove “serious and devastating for many reefs around the world”, he said, describing the prospect with “dread, although not surprise”.
Bleaching happens when seawater becomes too warm and coral loses the algae that give it colour and food. If the water cools quickly enough, coral can survive. If the heat lasts too long, coral can starve and die.
“If you’re being bleached before you’ve even recovered and been able to produce juveniles again, then that’s only a downwards trajectory from there,” Oakley said.
The last global mass bleaching event was declared in 2024.
In the Caribbean, some coral types are now “functionally extinct”, while Australia’s Great Barrier Reef lost between 15 and 40 percent of its coral cover in different places between 2024 and 2025.
Scientists are experimenting with techniques including nutritional gel, shading methods and genetic engineering to help protect reefs.
“There’s a lot of really important and innovative management strategies out there,” said Jen Matthews, a coral scientist at the University of Technology Sydney.
"But they’re all just buying time.”
El Nino is a natural climate pattern that develops in the Pacific every two to seven years and can disrupt weather around the world, bringing drought to some regions and heavy rain to others.
Forecasters at the US National Oceanic and Atmospheric Administration (NOAA) say there is about an 80 percent chance of El Nino developing by July.
Sea temperatures in key parts of the equatorial Pacific are climbing quickly, while a large pool of unusually warm water is building beneath the surface.
Several weather services predict Pacific temperatures could rise by 2.5C or more above average later this year. Only three El Nino events since 1877-78 have crossed the 2C mark, in 1982-83, 1997-98 and 2015-16.
“There’s definitely something coming. We’re very confident about that, and it looks like it will be a big event,” Adam Scaife, head of long-range prediction at the UK Met Office, told French news agency AFP.
Unpredictable winds
The NOAA says there is a one in three chance this episode will reach 2C or above, putting it in “super El Nino” territory. But scientists say its final strength will depend on winds that remain difficult to predict.
The strongest El Ninos usually form when trade winds weaken across the Pacific, allowing more warm water to spread across the ocean surface. But those winds can also strengthen unexpectedly.
“When that happens, it pauses the growth of El Nino or even reverses it,” said Michelle L’Heureux, NOAA’s El Nino-Southern Oscillation lead.
“Ultimately the strength of this event will be likely influenced by these details, like the low-level winds, which we cannot predict many months in advance.”
New record possible
El Nino tends to peak around December, but ocean heat is released slowly and can push global temperatures higher in the years that follow.
Many record-temperature years, including 1998, 2010, 2016, 2023 and 2024, came during or after major El Nino events.
There “could easily be a new record level of global warmth in 2027” if an extreme El Nino takes shape this year, Scaife said.
Even a weaker El Nino would be occurring in a world already warmed by climate change.
“The impacts of this El Nino – on things like rainfall and of course temperature – are riding on top of climate change, and could well be larger than anything we’ve seen in the past,” Scaife added.
Scientists also stress that stronger El Ninos raise the odds of more severe impact, but do not guarantee them.
Reefs under pressure
Researchers are also warning of a heavy toll on coral reefs, which have already suffered repeated bleaching as oceans warm.
“Every global coral bleaching event has been during an El Nino year,” explained Clint Oakley, a coral scientist at Victoria University of Wellington.
A strong El Nino could prove “serious and devastating for many reefs around the world”, he said, describing the prospect with “dread, although not surprise”.
Bleaching happens when seawater becomes too warm and coral loses the algae that give it colour and food. If the water cools quickly enough, coral can survive. If the heat lasts too long, coral can starve and die.
“If you’re being bleached before you’ve even recovered and been able to produce juveniles again, then that’s only a downwards trajectory from there,” Oakley said.
The last global mass bleaching event was declared in 2024.
In the Caribbean, some coral types are now “functionally extinct”, while Australia’s Great Barrier Reef lost between 15 and 40 percent of its coral cover in different places between 2024 and 2025.
Scientists are experimenting with techniques including nutritional gel, shading methods and genetic engineering to help protect reefs.
“There’s a lot of really important and innovative management strategies out there,” said Jen Matthews, a coral scientist at the University of Technology Sydney.
"But they’re all just buying time.”
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