The average global sea surface temperature reached a record 21.1 degrees Celsius (69.98 degrees Fahrenheit) on Friday and Saturday, according to the European Union’s Copernicus Climate Change Service. The reading exceeded the previous record of 21.09C (69.96F), set in March 2024.
Copernicus warned that a rapidly intensifying El Niño, combined with decades of human-caused warming, is placing “unprecedented strain” on the world’s oceans. The agency said the timing was particularly notable because global ocean temperatures usually peak in March and April, rather than August.
Why temperatures are still expected to rise
Samantha Burgess, strategic lead for climate at the European Centre for Medium-Range Weather Forecasts, said El Niño is adding heat to an ocean already warmed by long-term fossil-fuel-driven climate change. She noted that this underlying warming has raised ocean temperatures by 0.8C (1.44F).
El Niño is a natural, temporary warming of parts of the Pacific that alters weather patterns and raises temperatures globally. Burgess said the oceans are expected to continue warming until the current El Niño reaches its peak, forecast sometime between November and January.
Related coverage: Europe’s 2026 marine heatwaves linked to carbon pollution.
A stronger El Niño may be developing
The World Meteorological Organization expects El Niño to strengthen in the coming months. Copernicus said its seasonal forecasting system indicates the event could reach levels not seen for several decades.
The latest record therefore reflects both a short-term climate pattern and longer-term warming. Copernicus said the new high is another clear signal that the ocean is under growing stress.
What warmer oceans mean for people and ecosystems
Copernicus said higher ocean temperatures contribute to sea-level rise through thermal expansion and increase the likelihood and intensity of marine heatwaves. Those heatwaves can damage coral reefs and seagrass beds, disrupt food chains and threaten fishing and aquaculture.
More context: Ocean temperatures hit a record high outside polar regions.
Warmer oceans also absorb less carbon dioxide, weakening an important natural defence against climate change. They can supply more heat and moisture to the atmosphere, increasing the potential for extreme weather events and putting pressure on coastal communities.
Oceanographer Jane Lubchenco described the finding as troubling, saying a warmer ocean can destabilise weather patterns and threaten food security, economic prosperity and marine life.
Also read: Climate crisis causes £40bn damage to Caribbean islands from 2000 to 2024.
No comments yet. Start the discussion.