Globally averaged sea surface temperatures were the warmest on record Friday, according to the Copernicus Climate Change Service. The record occurred amid a surging El Niño and long-term human-caused global warming.
Copernicus Climate Change Service
Earth’s oceans were warmer than any day in recorded history Friday due to a combination of long-term human-caused global warming and short-term effects of El Niño.
The average sea surface temperature of 21.1 degrees Celsius, or 70 degrees Fahrenheit, breaks the old record of 21.09 degrees Celsius set many times in early 2024 during the most recent El Niño.
“There is quite a big certainty that sea surface temperatures globally are now higher than even the last warm period before the last ice age,” Leon Simons, a climate systems analyst and executive director of the Club of Rome Netherlands, said during a webinar Sunday.
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Measurements are based on data from satellites, buoys and ships between 60 degrees south and 60 degrees north latitude and analyzed by the Copernicus Climate Change Service. Daily measurements date back to 1979, though July sea surface temperatures were the warmest month globally since at least 1854.
On Friday, the average ocean surface temperature of 21.1 degrees Celsius, or 70 degrees Fahrenheit, was 0.67 degrees Celsius above the long-term normal. It was the warmest day of ocean surface temperatures since daily measurements began in 1979, though the most recent month was the warmest since at least the mid-19th century.
Copernicus Climate Change Service
The ocean has absorbed more than 90% of the excess heat from human-caused global warming.
As the ocean warms, sea levels rise, coral reefs die off, marine animals are threatened and weather patterns become more extreme.
El Niño, a naturally occurring pattern of warmer-than-normal water in the eastern equatorial Pacific, is also driving high temperatures across Earth’s oceans. El Niño alters currents throughout the Pacific and causes oceans to warm off the California coast, particularly in fall and winter.
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“Although El Niño events often provide a temporary boost to global temperatures, these new global climate records are ultimately being driven by human-caused climate change,” Climate Central, a nonprofit science research and communication organization, said in a press release.
This El Niño is already setting records for its unusual warmth for this time of year, but is not expected to peak until late fall or early winter.
“If this continues on the current trajectory, this is going to be an El Niño event that is without precedent,” said JP O’Brien, a climate scientist at Lawrence Berkeley National Laboratory.
Record ocean heat will have cascading effects on global weather throughout the coming months.
Warmer seas provide storms with more energy and moisture, which will make rainfall heavier and floods more likely in parts of the world. That may include California, as the arrangement of this El Niño is shaping up similarly to those that have soaked the state in the past.
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“If you have 20 to 40 atmospheric rivers in a winter and each one is 1% to 2% wetter, that translates to a lot of extra water coming down on land,” O’Brien said.
El Niño shifts rainfall patterns in many parts of the world, including in the southern U.S., where winter tends to be wetter than normal.
Columbia International Research Institute
The Pacific hurricane season is being supercharged by El Niño. Hawaii was devastated by Hurricane Lala last weekend, and enhanced tropical cyclone activity is expected to continue in the Pacific into fall.
Other parts of the world are suffering from an El Niño-induced drought, including Puerto Rico and the U.S. Virgin Islands.
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Land temperature anomalies tend to trail ocean temperatures by three months. As El Niño surges, scientists predict the final months of 2026 will break global heat records. These extremely high temperatures will continue through 2027, which will almost certainly be the warmest year ever recorded.